====== Building a Battery Powered Smart Lamp with the Analog Discovery Pro (ADP3450/ADP3250) ======
~~TechArticle~~
{{ :test-and-measurement:analog-discovery-pro-3x50:app_front.jpeg?200 |}}
In this guide, the processes of designing and building a battery-powered, Bluetooth-connected RGB lamp will be presented. The Analog Discovery Pro in Linux mode will be used to control the final project and to debug the external circuits during the testing stage. To make sure that you have the latest Linux image running on your device, follow this guide: [[test-and-measurement:analog-discovery-pro-3x50:recover-linux-mode|]]
----
===== Planning =====
Before starting designing the lamp, the goals of the project must be established. The central component of the lamp is an RGB LED which should be switched on/off via an application running on a phone. Communication with the phone can be resolved using Bluetooth or Bluetooth Low Energy, but the Low Energy variant (BLE) can be easier to use in some cases, due to the custom service characteristics (more on this later). The application should also display the ambient light conditions to notify the user to turn off the lamp if it isn't needed (automatic switching may be implemented if needed). To power the lamp, a battery can be used which can be charged from the Analog Discovery Pro (the lamp can't be directly powered from the ADP, as it doesn't provide enough current).
In this prototype, a 5 mm RGB LED will be used as the lamp, which is powered by an old phone battery, but the circuit can be scaled for higher power lamps if needed. Communication with the phone is resolved by the [[pmod:pmodble:start|]] (Bluetooth Low Energy) module and ambient light measurements are performed by the [[pmod:pmodals:start|]] (Ambient Light Sensor). The [[pmod:pmodda1:start|]] (Digital to Analog Converter) and the [[pmod:pmodod1:start|]] (Open Drain MOSFETs) will be used in the control circuit. A full inventory of the components needed is listed below.
----
===== Inventory =====
== Hardware ==
* [[test-and-measurement:analog-discovery-pro-3x50:start|Analog Discovery Pro (ADP3450/ADP3250)]]
* a smartphone with Android
* [[pmod:pmodble:start|]]
* [[pmod:pmodals:start|]]
* [[pmod:pmodda1:start|]]
* [[pmod:pmodod1:start|]]
* Lithium-Polymer (LiPo) battery cell
* RGB LED
* USB-A to Micro-USB cable
* [[https://www.analog.com/en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/EVAL-ADALP2000.html#eb-overview|ADALP2000 Analog Parts Kit]]
* USB connector
* LT3092 programmable current source
* OP484 operational amplifier
* 5mm LED
* 470Ω resistor
* 3x 100Ω resistor
* 47Ω resistor
* 10Ω resistor
== Software ==
* [[software:waveforms:waveforms-3:start]] (for debugging)
* [[https://code.visualstudio.com/|Visual Studio Code]], or any other editor of your choice
* a web browser
**Note:** //WaveForms can be installed by following the [[software:waveforms:waveforms-3:getting-started-guide]].//
----
===== Creating a Hardware Abstraction Layer (HAL) for the Analog Discovery Pro =====
A Hardware Abstraction Layer (HAL) is a layer in programming that takes the functions controlling the hardware and makes them more abstract, by generalizing them. In this case, the hardware, the Analog Discovery Pro, is controlled using WaveForms SDK, from a Python script. WaveForms SDK requires a fair amount of stuff to happen to start using an instrument. The SDK uses the ctypes module and most instruments need several initialization functions (like dummy read/write functions in the case of some digital communication protocols) before using them. As the current project uses several instruments, some sort of module is needed to make the interaction with the hardware more straightforward. In the following, a Python module will be created, which is based on WaveForms SDK and works like an instrument driver for the Analog Discovery Pro. If you are not interested in the details of this module, skip to the next section. The library containing the modules can be downloaded here: {{ :test-and-measurement:analog-discovery-pro-3x50:waveforms_hal.zip |waveforms_hal.zip}}.
In the attached package, not all the functions were tested, so errors might appear in some cases. Use the package responsibly and feel free to modify it.
Create a new folder and copy the **dwfconstants.py** file into it from WaveForms' installation path (usually //C:\Program Files (x86)\Digilent\WaveFormsSDK\samples\py\dwfconstants.py//). This file is needed as it contains all the constants needed for every instrument. Now create an initializer file and separate files for every instrument you want to use.
--> Wrapper: __init__.py #
This file imports all the other modules and also gives a name to each one of them. Global initialization and cleanup functions are also implemented here.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" WRAPPER """
# import every submodule
from WaveForms_HAL import WaveForms_HAL_Device as device
from WaveForms_HAL import WaveForms_HAL_Supply as supply
from WaveForms_HAL import WaveForms_HAL_Scope as scope
from WaveForms_HAL import WaveForms_HAL_Wavegen as wavegen
from WaveForms_HAL import WaveForms_HAL_Logic as logic
from WaveForms_HAL import WaveForms_HAL_Pattern as pattern
from WaveForms_HAL import WaveForms_HAL_Pattern_static as static_pattern
from WaveForms_HAL import WaveForms_HAL_Static as digital
from WaveForms_HAL import WaveForms_HAL_SPI as spi
from WaveForms_HAL import WaveForms_HAL_UART as uart
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
# synchronize submodules
def initialize():
# connect to the device
if device.connected != True:
device.open()
# copy device handles
supply.hdwf = device.hdwf
scope.hdwf = device.hdwf
wavegen.hdwf = device.hdwf
logic.hdwf = device.hdwf
pattern.hdwf = device.hdwf
digital.hdwf = device.hdwf
spi.hdwf = device.hdwf
uart.hdwf = device.hdwf
return
"""-------------------------------------------------------------------"""
""" CLEANUP """
"""-------------------------------------------------------------------"""
def close():
# close the device
if device.connected:
# reset all instruments
supply.reset()
scope.reset()
wavegen.reset()
logic.reset()
pattern.reset()
static_pattern.reset()
digital.reset()
spi.reset()
uart.reset()
device.close()
return
"""-------------------------------------------------------------------"""
<--
--> General: WaveForms_HAL_Device.py #
This file contains functions used for opening and closing the device and error checking. A flag showing the current connection status is also included here.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" MAIN FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
connected = False # the current state of the device
"""-------------------------------------------------------------------"""
""" ERROR CHECKING """
"""-------------------------------------------------------------------"""
def check_error():
# check for errors
errno = c_int() # variable for error number
dwf.FDwfGetLastError(errno) # get error number
# if there is an error
if errno != dwfercNoErc:
szerr = create_string_buffer(512) # variable for the error message
dwf.FDwfGetLastErrorMsg(szerr) # get the error message
print(str(szerr.value)) # print the error message
quit() # terminate the program
return
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def open():
# open the first connected device
dwf.FDwfDeviceOpen(c_int(-1), byref(hdwf))
# if there is a problem
if hdwf.value == hdwfNone.value:
# check for errors
check_error()
connected = True # set connection flag
return
"""-------------------------------------------------------------------"""
""" CLEANUP """
"""-------------------------------------------------------------------"""
def close():
dwf.FDwfDeviceClose(hdwf) # close the device
connected = False # set connection flag
return
"""-------------------------------------------------------------------"""
<--
--> Logic Analyzer: WaveForms_HAL_Logic.py #
This file contains functions controlling the logic analyzer. Besides the initialization and cleanup functions, the most important one is the receive_data() function, which reads the states of the digital I/O lines in a buffer according to the initialization parameters. The function accepts a parameter that specifies whether data specific to a digital I/O line should be selected from the dataset or not.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" DIGITAL INPUT FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import numpy
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
data_count = 8192 # buffer size
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(base_frequency=100e06, buffer_size=8192):
global data_count
data_count = buffer_size
# set internal clock frequency
internal_frequency = c_double()
dwf.FDwfDigitalInInternalClockInfo(hdwf, byref(internal_frequency))
dwf.FDwfDigitalInDividerSet(hdwf, c_int(
int(internal_frequency.value / base_frequency)))
# set 16-bit sample format
dwf.FDwfDigitalInSampleFormatSet(hdwf, c_int(16))
# set buffer size
dwf.FDwfDigitalInBufferSizeSet(hdwf, c_int(buffer_size))
return
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfDigitalInReset(hdwf) # reset the logic analyzer
return
"""-------------------------------------------------------------------"""
""" RECEIVE ALL DATA """
"""-------------------------------------------------------------------"""
def receive_data(channel=None):
# begin acquisition
dwf.FDwfDigitalInConfigure(hdwf, False, True)
while True:
status = c_byte()
dwf.FDwfDigitalInStatus(hdwf, True, byref(status))
if status.value == stsDone.value:
# exit loop when finished
break
# get samples
buffer = (c_uint16 * data_count)()
dwf.FDwfDigitalInStatusData(hdwf, buffer, 2 * data_count)
buffer = numpy.fromiter(buffer, dtype=numpy.uint16)
buffer = buffer.tolist()
# break out for every pin
result = [[] for _ in range(16)]
for data in buffer:
for index in range(16):
result[index].append(data & (1 << index))
# return only what is necessary
if channel != None:
return result[channel]
else:
return result
"""-------------------------------------------------------------------"""
<--
--> Pattern Generator: WaveForms_HAL_Pattern.py #
The most important part of this file is the function that generates the required signal on the required channel according to the input parameters.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" DIGITAL OUTPUT FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import WaveForms_HAL.WaveForms_HAL_Static as digital
import math
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
# function types
class type:
pulse = DwfDigitalOutTypePulse
custom = DwfDigitalOutTypeCustom
random = DwfDigitalOutTypeRandom
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfDigitalOutReset(hdwf) # reset the pattern generator
return
"""-------------------------------------------------------------------"""
""" GENERATION """
"""-------------------------------------------------------------------"""
def generate(channel, frequency, function, duty_cycle=50, data=None):
# reset pin
digital.stop(channel)
# get internal clock frequency
internal_frequency = c_double()
dwf.FDwfDigitalOutInternalClockInfo(hdwf, byref(internal_frequency))
# get counter value range
counter_limit = c_uint()
dwf.FDwfDigitalOutCounterInfo(hdwf, c_int(0), 0, byref(counter_limit))
# calculate the divider for the given frequency
divider = int(math.ceil(internal_frequency.value /
frequency / counter_limit.value))
# calculate counter steps to get the required frequency
steps = int(round(internal_frequency.value / frequency / divider))
# calculate steps for low and high parts of the period
high_steps = int(steps * duty_cycle / 100)
low_steps = int(steps - high_steps)
# enable the respective channel
dwf.FDwfDigitalOutEnableSet(hdwf, c_int(channel), c_int(1))
# set output type
dwf.FDwfDigitalOutTypeSet(hdwf, c_int(channel), function)
# set frequency
dwf.FDwfDigitalOutDividerSet(hdwf, c_int(channel), c_int(divider))
if function == type.pulse:
# set duty cycle
dwf.FDwfDigitalOutCounterSet(hdwf, c_int(
channel), c_int(low_steps), c_int(high_steps))
elif function == type.custom:
# format data
buffer = (c_ubyte * ((len(data) + 7) >> 3))(0)
for index in range(len(data)):
if data[index] != 0:
buffer[index >> 3] |= 1 << (index & 7)
# load data
dwf.FDwfDigitalOutDataSet(hdwf, c_int(
channel), byref(buffer), c_int(len(data)))
# start generating the signal
dwf.FDwfDigitalOutConfigure(hdwf, c_int(1))
return
"""-------------------------------------------------------------------"""
<--
--> Static Pattern Generator: WaveForms_HAL_Pattern_static.py #
Due to hardware limitations, if one instrument is initialized which uses a certain hardware part (like the digital I/O lines), all the other instruments which use the same hardware lose control over it, so, for example, the pattern generator, the UART master, and the SPI master instruments can't be used at the same time. However, the digital I/O lines still can be controlled in a static way, by using bitmasks.
To make use of this possibility, this library realizes the pattern generator functions using the static I/O instrument instead of the pattern generator. While this module can be used at the same time as other digital instruments, it has a very limited speed, which is not enough for the scope of this project.
The current version of this module uses multithreading to realize several operations in parallel (actually the processor just switches very fast between the tasks).
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" DIGITAL OUTPUT FUNCTIONS """
# import necessary modules
import WaveForms_HAL.WaveForms_HAL_Static as digital
import time
import threading
import random
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# list for processes
processes = [None, None, None, None,
None, None, None, None,
None, None, None, None,
None, None, None, None]
# class containing all channel parameters
class channel_data:
frequency = None
duty_cycle = None
signal_data = None
function_type = None
thread = None
stop = None
# function types
class type:
pulse = 0
custom = 1
random = 2
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# stop all threads
for index in range(16):
stop(index)
# reset the instrument
digital.reset() # reset the pattern generator
return
"""-------------------------------------------------------------------"""
""" STOP GENERATION """
"""-------------------------------------------------------------------"""
def stop(channel):
global processes
# stop the generation
if processes[channel] != None:
processes[channel].stop = True
processes[channel].thread.join()
processes[channel] = None
# reset the pin
digital.stop(channel)
return
"""-------------------------------------------------------------------"""
""" SET GENERATION DATA """
"""-------------------------------------------------------------------"""
def generate(channel, frequency, function, duty_cycle=None, data=None):
global processes
# stop running thread
if processes[channel] != None:
stop(channel)
# set pin as output
digital.set_output(channel)
# save current channel data
current_ch = channel_data()
current_ch.frequency = frequency
current_ch.duty_cycle = duty_cycle
current_ch.signal_data = data
current_ch.function_type = function
current_ch.stop = False
current_ch.thread = threading.Thread(target=channel_handler, args=(channel,))
# update data table
processes[channel] = current_ch
# start thread
processes[channel].thread.start()
return
"""-------------------------------------------------------------------"""
""" CHANNEL HANDLER FUNCTION """
"""-------------------------------------------------------------------"""
def channel_handler(channel):
global processes
loop_index = 0
# start looping
while processes[channel].stop != True:
# measure start time
start_time = time.time()
if processes[channel].function_type == type.pulse:
# calculate waiting times
period = 1 / processes[channel].frequency
high_period = period * processes[channel].duty_cycle / 100
low_period = period - high_period
# generate low cycle
digital.write(channel, False)
# wait
duration = time.time() - start_time
if duration < low_period:
time.sleep(low_period - duration)
# record starting time
start_time = time.time()
# generate high cycle
digital.write(channel, True)
# wait
duration = time.time() - start_time
if duration < high_period:
time.sleep(high_period - duration)
elif processes[channel].function_type == type.custom:
# generate custom signal
data = processes[channel].signal_data
digital.write(channel, data[loop_index % len(data)])
# wait
duration = time.time() - start_time
period = 1 / processes[channel].frequency
if duration < period:
time.sleep(period - duration)
else:
# generate random signal
digital.write(channel, random.choice([True, False]))
# wait
duration = time.time() - start_time
period = 1 / processes[channel].frequency
if duration < period:
time.sleep(period - duration)
# increment loop index
loop_index += 1
return
"""-------------------------------------------------------------------"""
<--
--> Oscilloscope: WaveForms_HAL_Scope.py #
This file contains functions that can command the oscilloscope to measure voltages on a specified channel or to fill a buffer with the recorded data point according to the settings with which the instrument was initialized.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" ANALOG INPUT FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import numpy
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
# triggering flag
trigger = False
# buffer size
data_count = 8192
# possible trigger options
class trig:
# sources
class src:
no = (trigsrcNone, )
scope_ch = [(trigsrcDetectorAnalogIn, 0), (trigsrcDetectorAnalogIn, 1),
(trigsrcDetectorAnalogIn, 2), (trigsrcDetectorAnalogIn, 3)]
digital_ch = [(trigsrcDetectorDigitalIn, 0), (trigsrcDetectorDigitalIn, 1),
(trigsrcDetectorDigitalIn, 2), (trigsrcDetectorDigitalIn, 3),
(trigsrcDetectorDigitalIn, 4), (trigsrcDetectorDigitalIn, 5),
(trigsrcDetectorDigitalIn, 6), (trigsrcDetectorDigitalIn, 7),
(trigsrcDetectorDigitalIn, 8), (trigsrcDetectorDigitalIn, 9),
(trigsrcDetectorDigitalIn, 10), (trigsrcDetectorDigitalIn, 11),
(trigsrcDetectorDigitalIn, 12), (trigsrcDetectorDigitalIn, 13),
(trigsrcDetectorDigitalIn, 14), (trigsrcDetectorDigitalIn, 15)]
external_ch = [(trigsrcExternal1, ), (trigsrcExternal2, ),
(trigsrcExternal3, ), (trigsrcExternal4, )]
# types
class type:
edge = trigtypeEdge
pulse = trigtypePulse
transition = trigtypeTransition
# edges
class edge:
rising = trigcondRisingPositive
falling = trigcondFallingNegative
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(offset=0, range=10, buffer_size=8192, frequency=20e06, trigger=False, trigger_src=trig.src.no, trigger_type=trig.type.edge, trigger_timeout=0, trigger_lvl=0, trigger_edge=trig.edge.rising):
global data_count
data_count = buffer_size
# enable all channels
dwf.FDwfAnalogInChannelEnableSet(hdwf, c_int(0), c_bool(True))
# set offset voltage
dwf.FDwfAnalogInChannelOffsetSet(hdwf, c_int(0), c_double(offset))
# set range
dwf.FDwfAnalogInChannelRangeSet(hdwf, c_int(0), c_double(range / 2))
# set the buffer size
dwf.FDwfAnalogInBufferSizeSet(hdwf, c_int(buffer_size))
# set the acquisition frequency
dwf.FDwfAnalogInFrequencySet(hdwf, c_double(frequency))
# disable averaging
dwf.FDwfAnalogInChannelFilterSet(hdwf, c_int(-1), filterDecimate)
# set up triggering
if trigger:
# enable/disable auto triggering
dwf.FDwfAnalogInTriggerAutoTimeoutSet(hdwf, c_double(trigger_timeout))
# set trigger source
dwf.FDwfAnalogInTriggerSourceSet(hdwf, trigger_src[0])
if trigger_src[1] != None:
dwf.FDwfAnalogInTriggerChannelSet(hdwf, c_int(trigger_src[1]))
# set trigger type
dwf.FDwfAnalogInTriggerTypeSet(hdwf, trigger_type)
# set trigger level
dwf.FDwfAnalogInTriggerLevelSet(hdwf, c_double(trigger_lvl))
# set trigger edge
dwf.FDwfAnalogInTriggerConditionSet(hdwf, trigger_edge)
return
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfAnalogInReset(hdwf) # reset the oscilloscope
return
"""-------------------------------------------------------------------"""
""" MEASURE VOLTAGE """
"""-------------------------------------------------------------------"""
def measure(channel):
# set up the instrument
dwf.FDwfAnalogInConfigure(hdwf, c_bool(False), c_bool(False))
# read data to buffer
dwf.FDwfAnalogInStatus(hdwf, False, None)
# extract data from buffer
voltage = c_double()
dwf.FDwfAnalogInStatusSample(hdwf, c_int(channel - 1), byref(voltage))
return voltage.value
"""-------------------------------------------------------------------"""
""" RECEIVE DATA """
"""-------------------------------------------------------------------"""
def receive(channel):
# set up the instrument
dwf.FDwfAnalogInConfigure(hdwf, c_bool(False), c_bool(True))
# read data to buffer
while True:
status = c_byte()
dwf.FDwfAnalogInStatus(hdwf, True, byref(status))
if status.value == DwfStateDone.value:
# exit loop when ready
break
# copy buffer
buffer = (c_double * data_count)()
dwf.FDwfAnalogInStatusData(hdwf, c_int(channel - 1), buffer, data_count)
# convert list
buffer = numpy.fromiter(buffer, dtype=numpy.float)
buffer = buffer.tolist()
return buffer
"""-------------------------------------------------------------------"""
<--
--> Serial Peripheral Interface (SPI) Master: WaveForms_HAL_SPI.py #
The Analog Discovery Pro can initiate SPI communication on any of the digital pins, after which it can exchange data with the connected slave device.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" SPI FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
# endianness
class bit_order:
MSB_first = 1
LSB_first = 0
# pins
class pins:
cs = None
sck = None
mosi = None
miso = None
"""-------------------------------------------------------------------"""
""" SPI INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(cs_pin, sck_pin, miso_pin=None, mosi_pin=None, frequency=1e06, mode=0, order=bit_order.MSB_first):
# save pin numbers globally
pins.cs = cs_pin
pins.sck = sck_pin
pins.mosi = mosi_pin
pins.miso = miso_pin
dwf.FDwfDigitalSpiFrequencySet(hdwf, c_double(
frequency)) # set the clock frequency
dwf.FDwfDigitalSpiClockSet(hdwf, c_int(sck_pin)) # set the clock pin
if mosi_pin != None:
dwf.FDwfDigitalSpiDataSet(hdwf, c_int(
0), c_int(mosi_pin)) # set the mosi pin
dwf.FDwfDigitalSpiIdleSet(hdwf, c_int(
0), DwfDigitalOutIdleZet) # set the initial state
if miso_pin != None:
dwf.FDwfDigitalSpiDataSet(hdwf, c_int(
1), c_int(miso_pin)) # set the miso pin
dwf.FDwfDigitalSpiIdleSet(hdwf, c_int(
1), DwfDigitalOutIdleZet) # set the initial state
dwf.FDwfDigitalSpiModeSet(hdwf, c_int(mode)) # set the SPI mode
dwf.FDwfDigitalSpiOrderSet(hdwf, c_int(order)) # set endianness
dwf.FDwfDigitalSpiSelect(hdwf, c_int(
cs_pin), c_int(1)) # set the cs pin HIGH
dwf.FDwfDigitalSpiWriteOne(hdwf, c_int(
1), c_int(0), c_int(0)) # dummy write
return
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfDigitalSpiReset(hdwf) # reset the SPI interface
return
"""-------------------------------------------------------------------"""
""" SPI SENDING """
"""-------------------------------------------------------------------"""
def send(data):
# cast data
if type(data) == int:
data = "".join(chr(data))
elif type(data) == list:
data = "".join(chr(element) for element in data)
# enable the chip select line
dwf.FDwfDigitalSpiSelect(hdwf, c_int(pins.cs), c_int(0))
# create buffer to write
data = (c_ubyte * len(data))(*[c_ubyte(ord(character)) for character in data])
dwf.FDwfDigitalSpiWrite(hdwf, c_int(1), c_int(8), data, c_int(
len(data))) # write array of 8 bit elements
# disable the chip select line
dwf.FDwfDigitalSpiSelect(hdwf, c_int(pins.cs), c_int(1))
return
"""-------------------------------------------------------------------"""
""" SPI RECEIVING """
"""-------------------------------------------------------------------"""
def receive(count):
# enable the chip select line
dwf.FDwfDigitalSpiSelect(hdwf, c_int(pins.cs), c_int(0))
# create buffer to store data
buffer = (c_ubyte*count)()
dwf.FDwfDigitalSpiRead(hdwf, c_int(1), c_int(8), buffer, c_int(
len(buffer))) # read array of 8 bit elements
# disable the chip select line
dwf.FDwfDigitalSpiSelect(hdwf, c_int(pins.cs), c_int(1))
# decode data
data = [str(bin(element))[2:] for element in buffer]
data = [int(element, 2) for element in data]
data = "".join(chr(element) for element in data)
return data
"""-------------------------------------------------------------------"""
""" SPI EXCHANGE """
"""-------------------------------------------------------------------"""
def exchange(data, count):
# cast data
if type(data) == int:
data = "".join(chr(data))
elif type(data) == list:
data = "".join(chr(element) for element in data)
# enable the chip select line
dwf.FDwfDigitalSpiSelect(hdwf, c_int(pins.cs), c_int(0))
# create buffer to write
tx_buff = (c_ubyte * len(data)).from_buffer_copy(data)
# create buffer to store data
rx_buff = (c_ubyte*count)()
dwf.FDwfDigitalSpiWriteRead(hdwf, c_int(1), c_int(8), tx_buff, c_int(
len(tx_buff)), rx_buff, c_int(len(rx_buff))) # write to MOSI and read from MISO
# decode data
data = [str(bin(element))[2:] for element in rx_buff]
data = [int(element, 2) for element in data]
data = "".join(chr(element) for element in data)
# disable the chip select line
dwf.FDwfDigitalSpiSelect(hdwf, c_int(pins.cs), c_int(1))
return data
"""-------------------------------------------------------------------"""
<--
--> Static I/O: WaveForms_HAL_Static.py #
This module can read/write the state of a digital I/O line and can set the line as input, or output.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" DIGITAL I/O FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfDigitalIOReset(hdwf) # reset the digital I/O
return
"""-------------------------------------------------------------------"""
""" RESET PIN """
"""-------------------------------------------------------------------"""
def stop(pin):
# set pin to LOW
write(pin, False)
# disable static I/O
set_output(pin, False)
return
"""-------------------------------------------------------------------"""
""" READING A DIGITAL PIN """
"""-------------------------------------------------------------------"""
def read(pin):
# read a digital pin
# load internal buffer with current state of the pins
dwf.FDwfDigitalIOStatus(hdwf)
data = c_uint32() # variable for this current state
# get the current state of the pins
dwf.FDwfDigitalIOInputStatus(hdwf, byref(data))
# convert the state to a 16 character binary string
data = list(bin(data.value)[2:].zfill(16))
# check the required bit
if data[15 - pin] != "0":
# if it is one, return True (HIGH)
return True
else:
# else return False (LOW)
return False
"""-------------------------------------------------------------------"""
""" SETTING A DIGITAL PIN AS OUTPUT """
"""-------------------------------------------------------------------"""
def set_output(pin, state=True):
# set a pin as output
# load current state of the output enable buffer
mask = c_uint16()
dwf.FDwfDigitalIOOutputEnableGet(hdwf, byref(mask))
# set bit mask
mask = set_mask(pin, mask, state)
# set the pin to output
dwf.FDwfDigitalIOOutputEnableSet(hdwf, c_int(mask))
return
"""-------------------------------------------------------------------"""
""" WRITING A DIGITAL PIN """
"""-------------------------------------------------------------------"""
def write(pin, state):
# set a pin as output
# load current state of the output state buffer
mask = c_uint16()
dwf.FDwfDigitalIOOutputGet(hdwf, byref(mask))
# set bit mask
mask = set_mask(pin, mask, state)
# set the pin state
dwf.FDwfDigitalIOOutputSet(hdwf, c_int(mask))
return
"""-------------------------------------------------------------------"""
""" SET MASK """
"""-------------------------------------------------------------------"""
def set_mask(pin, mask, value):
# convert to list
mask = list(bin(mask.value)[2:].zfill(16))
# set bit
if value:
mask[15 - pin] = "1"
else:
mask[15 - pin] = "0"
# convert to number
mask = "".join(element for element in mask)
mask = int(mask, 2)
return mask
"""-------------------------------------------------------------------"""
<--
--> Supplies: WaveForms_HAL_Supply.py #
This module can turn on/off the 3.3V power supply
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" POWER SUPPLY FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfAnalogIOReset(hdwf) # reset the power supplies
return
"""-------------------------------------------------------------------"""
""" COMMANDING THE POWER SUPPLIES """
"""-------------------------------------------------------------------"""
def switch(state):
# start/stop the power supplies
# set the output voltage to 3.3V
dwf.FDwfAnalogIOChannelNodeSet(hdwf, c_int(0), c_int(0), c_double(3.3))
# start/stop the supplies
dwf.FDwfAnalogIOEnableSet(hdwf, c_int(state))
return
"""-------------------------------------------------------------------"""
<--
--> Universal Asynchronous Receiver-Transmitter (UART) Master: WaveForms_HAL_UART.py #
This module can be used to initialize UART communication on any of the digital I/O lines, then send/receive data on those lines.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" UART FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
# possible parity settings
class parity:
none = 0
odd = 1
even = 2
"""-------------------------------------------------------------------"""
""" UART INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(rx_pin, tx_pin, baud_rate=9600, parity=parity.none, data_bits=8, stop_bits=1):
dwf.FDwfDigitalUartRateSet(hdwf, c_double(baud_rate)) # set baud rate
dwf.FDwfDigitalUartTxSet(hdwf, c_int(tx_pin)) # set tx pin
dwf.FDwfDigitalUartRxSet(hdwf, c_int(rx_pin)) # set rx pin
dwf.FDwfDigitalUartBitsSet(hdwf, c_int(data_bits)) # set data bit count
# set parity bit requirements
dwf.FDwfDigitalUartParitySet(hdwf, c_int(parity))
dwf.FDwfDigitalUartStopSet(hdwf, c_double(stop_bits)) # set stop bit count
# initialize tx with idle levels
reset_tx()
reset_rx()
return
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfDigitalUartReset(hdwf) # reset the UART interface
return
"""-------------------------------------------------------------------"""
""" RESET RX """
"""-------------------------------------------------------------------"""
def reset_rx():
# initialize rx (dummy receive)
dummy_buffer = c_int(0)
dummy_parity_flag = c_int(0)
dwf.FDwfDigitalUartRx(hdwf, None, c_int(0), byref(dummy_buffer), byref(
dummy_parity_flag))
return
"""-------------------------------------------------------------------"""
""" RESET TX """
"""-------------------------------------------------------------------"""
def reset_tx():
# initialize tx with idle level (dummy send)
dwf.FDwfDigitalUartTx(hdwf, None, c_int(0))
return
"""-------------------------------------------------------------------"""
""" UART SENDING """
"""-------------------------------------------------------------------"""
def send(data):
# cast data
if type(data) == int:
data = "".join(chr(data))
elif type(data) == list:
data = "".join(chr(element) for element in data)
# encode the string into a string buffer
data = create_string_buffer(data.encode("UTF-8"))
# send text, trim zero ending
dwf.FDwfDigitalUartTx(hdwf, data, c_int(sizeof(data)-1))
return
"""-------------------------------------------------------------------"""
""" UART RECEIVING """
"""-------------------------------------------------------------------"""
def receive(chunk="", error="no error"):
data = create_string_buffer(8193) # create empty string buffer
count = c_int(0) # character counter
parity_flag = c_int(0) # parity check result
dwf.FDwfDigitalUartRx(hdwf, data, c_int(
sizeof(data)-1), byref(count), byref(parity_flag)) # read up to 8k characters
if count.value > 0:
data[count.value] = 0 # add zero ending
# make a string from the string buffer
data = list(data.value)
data = "".join(chr(element) for element in data)
# attach previous data
data = chunk + data
# decode parity check results
if parity_flag.value == 0 and error == "no error":
parity_flag = "no error"
elif parity_flag.value < 0:
parity_flag = "buffer overflow"
elif parity_flag.value > 0:
parity_flag = "parity error: {}".format(parity_flag.value)
else:
parity_flag = error
# propagate previous results
data, parity_flag = receive(chunk=data, error=parity_flag)
else:
data = chunk
parity_flag = error
return data, parity_flag
"""-------------------------------------------------------------------"""
<--
--> Waveform Generator: WaveForms_HAL_Wavegen.py #
This module can be used to generate analog signals with the required parameters. Possible functions are also present in the module as class members.
""" This module realizes communication with the Analog Discovery Pro using the WaveForms SDK"""
""" ANALOG OUTPUT FUNCTIONS """
# import necessary modules
from ctypes import *
from WaveForms_HAL.dwfconstants import *
import sys
if sys.platform.startswith("win"):
dwf = cdll.dwf
elif sys.platform.startswith("darwin"):
dwf = cdll.LoadLibrary("/Library/Frameworks/dwf.framework/dwf")
else:
dwf = cdll.LoadLibrary("libdwf.so")
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
# global variables
hdwf = c_int() # device handle
# function types
class type:
custom = funcCustom
sine = funcSine
square = funcSquare
triangle = funcTriangle
noise = funcNoise
dc = funcDC
pulse = funcPulse
trapezium = funcTrapezium
sine_power = funcSinePower
class ramp:
up = funcRampUp
down = funcRampDown
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# reset the instrument
dwf.FDwfAnalogOutReset(hdwf) # reset the waveform generator
return
"""-------------------------------------------------------------------"""
""" GENERATION """
"""-------------------------------------------------------------------"""
def generate(channel, function, amplitude, frequency=1e03, symmetry=50, offset=0, data=None, run_time=0, wait_time=0, repeat_time=0):
# enable channel
channel -= 1
dwf.FDwfAnalogOutNodeEnableSet(
hdwf, channel, AnalogOutNodeCarrier, c_bool(True))
# set function type
dwf.FDwfAnalogOutNodeFunctionSet(
hdwf, channel, AnalogOutNodeCarrier, function)
if function == type.custom:
dwf.FDwfAnalogOutNodeDataSet(
hdwf, channel, AnalogOutNodeCarrier, data, len(data))
# set frequency
dwf.FDwfAnalogOutNodeFrequencySet(
hdwf, channel, AnalogOutNodeCarrier, c_double(frequency))
# set amplitude
dwf.FDwfAnalogOutNodeAmplitudeSet(
hdwf, channel, AnalogOutNodeCarrier, c_double(amplitude))
# set offset
if function == type.dc:
dwf.FDwfAnalogOutNodeOffsetSet(
hdwf, channel, AnalogOutNodeCarrier, c_double(amplitude))
else:
dwf.FDwfAnalogOutNodeOffsetSet(
hdwf, channel, AnalogOutNodeCarrier, c_double(offset))
# set symmetry
dwf.FDwfAnalogOutNodeSymmetrySet(
hdwf, channel, AnalogOutNodeCarrier, c_double(symmetry))
# set running time limit
dwf.FDwfAnalogOutRunSet(hdwf, channel, c_double(run_time))
# set wait time before start
dwf.FDwfAnalogOutWaitSet(hdwf, channel, c_double(wait_time))
# set number of repeating cycles
dwf.FDwfAnalogOutRepeatSet(hdwf, channel, c_int(repeat_time))
# start
dwf.FDwfAnalogOutConfigure(hdwf, channel, c_bool(True))
return
"""-------------------------------------------------------------------"""
<--
----
===== Creating a Library for the Pmods =====
Now a library should be created to control the Pmods easily. These Pmod drivers will be created in a similar way to the HAL, but will use it to control the hardware. If you are not interested in the details of this module, skip to the next section. The library containing the modules can be downloaded {{ :test-and-measurement:analog-discovery-pro-3x50:pmod.zip |here}}.
In the attached package, not all the functions were tested, so errors might appear in some cases. Use the package on your own responsibility and feel free to modify it.
Create a new folder and inside create an initializer file and separate files for every Pmod you want to use.
--> Wrapper: __init__.py #
This module imports all submodules and names them
""" This module realizes communication with multiple PMODs """
""" WRAPPER """
from PMOD import PMOD_ALS as ALS
from PMOD import PMOD_BLE as BLE
from PMOD import PMOD_DA1 as DA1
from PMOD import PMOD_KYPD as KYPD
from PMOD import PMOD_OD1 as OD1
<--
--> Pmod ALS: PMOD_ALS.py #
The ambient light sensor uses the SPI interface for communication, with three lines (chip select, serial data out and serial clock) and a clock frequency between 1MHz and 4MHz. The on-board analog to digital converter returns 2 bytes of data, most significant bit first, which contain 3 leading and 4 trailing zeros. The sensor saturates at the output value 127. The module also converts the raw data into percentage.
""" This module realizes communication with the Pmod ALS """
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
class pins:
cs = 0 # CS pin of the Pmod
sdo = 1 # SDO pin of the Pmod
sck = 2 # SCK pin of the Pmod
# WaveForms SDK HAL object
WF = None
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(WaveForms_HAL):
global WF
WF = WaveForms_HAL
# start the power supply
WF.supply.switch(True)
# initialize the SPI interface
WF.spi.initialize(cs_pin=pins.cs, sck_pin=pins.sck,
miso_pin=pins.sdo, frequency=1e06)
return
"""-------------------------------------------------------------------"""
""" CLEANUP """
"""-------------------------------------------------------------------"""
def close():
pass
return
"""-------------------------------------------------------------------"""
""" RECEIVE DATA """
"""-------------------------------------------------------------------"""
def receive_data():
data = WF.spi.receive(2) # read 2 bytes
msb = ord(data[0]) & 0xFF
lsb = ord(data[1]) & 0xFF
# concatenate bytes without trailing and leading zeros
result = ((msb << 3) | (lsb >> 4)) & 0xFF
return result
"""-------------------------------------------------------------------"""
""" RECEIVE PERCENTAGE """
"""-------------------------------------------------------------------"""
def receive_percent():
# receive and convert raw data
data = receive_data() * 100 / 127
return round(data, 2)
"""-------------------------------------------------------------------"""
<--
--> Pmod BLE: PMOD_BLE.py #
The Pmod BLE is a Bluetooth Low Energy module, which communicates on UART interface, using a 115200bps baud rate. The controlling module contains functions to factory reset the device by putting it into command mode and sending the necessary commands. Besides that, it also can send and receive data, decoding the received bytes and separating the buffer into a list which contains only data and one which contains only system messages (starting and ending with "%").
""" This module realizes communication with the Pmod BLE """
import time
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
class pins:
rx = 0 # TX pin of the Pmod
tx = 1 # RX pin of the Pmod
rst = 2 # RESET pin of the Pmod
class commands:
command_mode = "$$$" # enter command mode
data_mode = "---\r" # enter data mode
rename = "S-,PmodBLE\r" # set name to PmodBLE_XXXX
factory_reset = "SF,1\r" # factory reset
high_power = "SGA,0\r" # set high power output
code = "SP,123456\r" # set pin code to "123456"
mode = "SS,C0\r" # support device info + UART Transparent
reboot = "R,1\r" # reboots the device
# WaveForms SDK HAL object
WF = None
# variables for detecting system messages
currently_sys = False
previous_msg = ""
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(WaveForms_HAL, first_run=False):
global WF
WF = WaveForms_HAL
# start the power supply
WF.supply.switch(True)
# initialize the UART interface
WF.uart.initialize(rx_pin=pins.tx, tx_pin=pins.rx, baud_rate=115200)
# factory reset the Pmod
if first_run:
reset()
return
"""-------------------------------------------------------------------"""
""" REBOOT """
"""-------------------------------------------------------------------"""
def reboot():
# hard reset the device
# pull down the reset line
WF.digital.write(pins.rst, False)
# wait
time.sleep(1)
# pull up the reset line
WF.digital.write(pins.rst, True)
return
"""-------------------------------------------------------------------"""
""" RESET """
"""-------------------------------------------------------------------"""
def reset():
# enter command mode
send_command(commands.command_mode)
time.sleep(3)
# factory reset the Pmod
success = send_command(commands.factory_reset)
while success != True:
success = send_command(commands.factory_reset)
time.sleep(1)
# enter command mode
send_command(commands.command_mode)
time.sleep(3)
# rename device
send_command(commands.rename)
time.sleep(1)
# set high power mode
send_command(commands.high_power)
time.sleep(1)
# set communication mode
send_command(commands.mode)
time.sleep(1)
# exit command mode
send_command(commands.data_mode)
time.sleep(3)
return
"""-------------------------------------------------------------------"""
""" CLEANUP """
"""-------------------------------------------------------------------"""
def close():
# restart the module
reboot()
return
"""-------------------------------------------------------------------"""
""" SEND COMMAND """
"""-------------------------------------------------------------------"""
def send_command(command):
# send the command
send_data(command)
# record response
response, _, error = receive_data
# analyze response
response = response[0:3]
if response == "ERR" or response == "Err" or error != "no error":
return False
return True
"""-------------------------------------------------------------------"""
""" SEND DATA """
"""-------------------------------------------------------------------"""
def send_data(data):
# send data
WF.uart.send(data)
return
"""-------------------------------------------------------------------"""
""" RECEIVE DATA """
"""-------------------------------------------------------------------"""
def receive_data():
global previous_msg, currently_sys
# record incoming message
data, error = WF.uart.receive()
sys_msg = ""
# check for system messages
special = data.count("%")
"""---------------------------------"""
if special == 0:
if currently_sys:
# the middle of a system message
previous_msg = previous_msg + data
data = ""
else:
# not a system message
pass
"""---------------------------------"""
elif special == 2:
# clear system message
sys_msg = data
data = ""
currently_sys = False
previous_msg = ""
"""---------------------------------"""
else:
# fragmented system message
data_list = data.split("%")
if currently_sys:
# the end of the message
sys_msg = previous_msg + data_list[0] + "%"
currently_sys = False
previous_msg = ""
data = data_list[1]
else:
# the start of the message
currently_sys = True
previous_msg = "%" + data_list[1]
data = data_list[0]
return data, sys_msg, error
"""-------------------------------------------------------------------"""
<--
--> Pmod DA1: PMOD_DA1.py #
The digital to analog converter also communicates via the SPI interface. The Pmod DA1 includes two DAC chips that have common chip select and serial clock pins. Both chips contain two 8-bit DAC channels, so in total, the Pmod features four different conversion channels. The program computes the 8-bit data word from the voltage, then appends it to the command word specific to the DAC channel. To use chip 1, or chip 2, the command and data words must be sent on the data 0, or data 1 lines.
""" This module realizes communication with the Pmod DA1 """
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
class pins:
sync = 0 # CS pin of the Pmod
d0 = 1 # data 0 pin of the Pmod
d1 = 2 # data 0 pin of the Pmod
sck = 3 # SCK pin of the Pmod
class output_channel:
# channels of the digital to analog converter
A1 = 0
B1 = 1
A2 = 2
B2 = 3
# voltage limits in Volts
max_voltage = 3.3
min_voltage = 0
# WaveForms SDK HAL object
WF = None
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(WaveForms_HAL):
global WF
WF = WaveForms_HAL
# start the power supply
WF.supply.switch(True)
return
"""-------------------------------------------------------------------"""
""" CLEANUP """
"""-------------------------------------------------------------------"""
def close():
pass
return
"""-------------------------------------------------------------------"""
""" SEND VOLTAGE """
"""-------------------------------------------------------------------"""
def output_voltage(channel, voltage):
# select DAC chip
mosi = pins.d0
if channel == output_channel.A2 or channel == output_channel.B2:
mosi = pins.d1
# initialize the SPI interface
WF.spi.initialize(cs_pin=pins.sync, sck_pin=pins.sck,
mosi_pin=mosi, frequency=1e06)
# limit and encode voltage
voltage = max(min(voltage, max_voltage), min_voltage)
data = round(voltage * 255 / 3.3) & 0xFF
# select channel
command = 3
if channel == output_channel.B1 or channel == output_channel.B2:
command = 7
# send both words
WF.spi.send([command, data])
return
"""-------------------------------------------------------------------"""
<--
--> Pmod KYPD: PMOD_KYPD.py #
This module uses the static I/O instrument to read the current state of the keypad and returns the pressed keys.
""" This module realizes communication with the Pmod KYPD """
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
class pins:
rows = [7, 6, 5, 4] # pins connected to keypad rows
columns = [3, 2, 1, 0] # pins connected to keypad columns
# the layout of the keypad
keymap = [["1", "2", "3", "A"],
["4", "5", "6", "B"],
["7", "8", "9", "C"],
["0", "F", "E", "D"]]
# WaveForms SDK HAL object
WF = None
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(WaveForms_HAL):
global WF
WF = WaveForms_HAL
# enable the power supply
WF.supply.switch(True)
# for every pin connected to a row
for pin in pins.rows:
WF.digital.set_output(pin) # set the pin as output
WF.digital.write(pin, False) # set a starting state of LOW
return
"""-------------------------------------------------------------------"""
""" CLEANUP """
"""-------------------------------------------------------------------"""
def close():
pass
return
"""-------------------------------------------------------------------"""
""" GETTING THE KEYPAD STATE """
"""-------------------------------------------------------------------"""
def receive_data():
# get the current state of the Pmod KYPD
result = [] # buffer to store the results
# go through all the rows
for index_1 in range(len(pins.rows)):
# set the state of every row
for index_2 in range(len(pins.rows)):
# only one row is HIGH at every moment
if index_1 == index_2:
# set the current row HIGH
WF.digital.write(pins.rows[index_2], True)
else:
# set the current row LOW
WF.digital.write(pins.rows[index_2], False)
# check every column
for index_2 in range(len(pins.columns)):
# if the current column is HIGH
if WF.digital.read(pins.columns[index_2]):
# append the respective key to the results
result.append(keymap[index_1][index_2])
# return the results
return result
"""-------------------------------------------------------------------"""
<--
--> Pmod OD1: PMOD_OD1.py #
The Pmod OD1 contains four open drain MOSFETs, which act like switches: if a gate pin is set HIGH (True), the respective MOSFET grounds the connected line. If the gate pin is set to LOW (False), the MOSFET input (the drain) has high impedance. The module realizes functions for turning the switches on/off, toggling and driving them with a pulse width modulated (PWM) signal. When driving the MOSFETs with the PWM signal, the type of signal generation (static, or pattern generator) can be defined as a parameter.
""" This module realizes communication with the Pmod ALS """
"""-------------------------------------------------------------------"""
""" VARIABLES """
"""-------------------------------------------------------------------"""
class pins:
g1 = 0 # G1 pin of the Pmod
g2 = 1 # G2 pin of the Pmod
g3 = 2 # G3 pin of the Pmod
g4 = 3 # G4 pin of the Pmod
# WaveForms SDK HAL object
WF = None
"""-------------------------------------------------------------------"""
""" INITIALIZATION """
"""-------------------------------------------------------------------"""
def initialize(WaveForms_HAL):
global WF
WF = WaveForms_HAL
# start the power supply
WF.supply.switch(True)
return
"""-------------------------------------------------------------------"""
""" CLEANUP """
"""-------------------------------------------------------------------"""
def close():
WF.static_pattern.reset()
return
"""-------------------------------------------------------------------"""
""" SWITCH ON """
"""-------------------------------------------------------------------"""
def on(channel):
pin = None
if channel == 1:
pin = pins.g1
elif channel == 2:
pin = pins.g2
elif channel == 3:
pin = pins.g3
elif channel == 4:
pin = pins.g4
if pin != None:
# initialize the pins
WF.static_pattern.stop(pin)
WF.digital.set_output(pin)
# switch on MOSFET
WF.digital.write(pin, True)
return
"""-------------------------------------------------------------------"""
""" SWITCH OFF """
"""-------------------------------------------------------------------"""
def off(channel):
pin = None
if channel == 1:
pin = pins.g1
elif channel == 2:
pin = pins.g2
elif channel == 3:
pin = pins.g3
elif channel == 4:
pin = pins.g4
if pin != None:
# initialize the pins
WF.static_pattern.stop(pin)
WF.digital.set_output(pin)
# switch off MOSFET 4
WF.digital.write(pin, False)
return
"""-------------------------------------------------------------------"""
""" SWITCH """
"""-------------------------------------------------------------------"""
def switch(channel):
pin = None
if channel == 1:
pin = pins.g1
elif channel == 2:
pin = pins.g2
elif channel == 3:
pin = pins.g3
elif channel == 4:
pin = pins.g4
if pin != None:
# initialize the pins
WF.static_pattern.stop(pin)
WF.digital.set_output(pin)
# switch off MOSFET 4
state = WF.digital.read(pin)
WF.digital.write(pin, not state)
return
"""-------------------------------------------------------------------"""
""" DRIVE MOSFET WITH PWM SIGNAL """
"""-------------------------------------------------------------------"""
def drive(channel, frequency, duty_cycle, static=False):
# enable/disable running in the background
instrument = WF.pattern
if static:
instrument = WF.static_pattern
if channel == 1:
# drive MOSFET 1
instrument.generate(pins.g1, frequency,
instrument.type.pulse, duty_cycle=duty_cycle)
elif channel == 2:
# drive MOSFET 2
instrument.generate(pins.g2, frequency,
instrument.type.pulse, duty_cycle=duty_cycle)
elif channel == 3:
# drive MOSFET 3
instrument.generate(pins.g3, frequency,
instrument.type.pulse, duty_cycle=duty_cycle)
elif channel == 4:
# drive MOSFET 4
instrument.generate(pins.g4, frequency,
instrument.type.pulse, duty_cycle=duty_cycle)
return
"""-------------------------------------------------------------------"""
<--
----
===== Testing the Modules =====
To make sure that the previously created Python modules work (and to provide examples for later usage), they should be tested. If you are not interested in the details of this testing, skip to the next section. The test scripts can be downloaded {{ :test-and-measurement:analog-discovery-pro-3x50:tests.zip |here}}.
Create test files for all Pmods and the Analog and Digital input-output instruments in the same folder, where the //WaveForms_HAL// and //PMOD// folders are.
--> Testing the Oscilloscope and the Waveform Generator: Test_HAL_Analog.py #
To test the functionality of the analog input-output modules, first connect an oscilloscope channel to one of the waveform generator's channels, then output a DC voltage on the waveform generator and measure it with the scope. An AC signal should also be outputted and read back with the scope, then plotted using the matplotlib module.
{{ :test-and-measurement:analog-discovery-pro-3x50:analog_test.png?400 |}}
# import modules
import WaveForms_HAL as WF
import matplotlib.pyplot as plt
# define used channels
scope_ch = 1
wavegen_ch = 1
# define signal parameters
dc_voltage = 2.25
sin_amplitude = 2.0
sin_frequency = 50e03
try:
# initialize the interface
WF.initialize()
# initialize the scope with default settings
WF.scope.initialize()
# output a DC voltage
WF.wavegen.generate(wavegen_ch, WF.wavegen.type.dc, dc_voltage)
# display measured voltage level
print(WF.scope.measure(scope_ch))
# output a sine signal
WF.wavegen.generate(wavegen_ch, WF.wavegen.type.sine,
amplitude=sin_amplitude, frequency=sin_frequency)
while True:
plt.plot(WF.scope.receive(scope_ch)) # plot recorded signal
plt.show()
except KeyboardInterrupt:
pass
finally:
# close device
WF.close()
<--
--> Testing the Logic Analyzer and the Pattern Generator: Test_HAL_Digital.py #
To test the functionality of the digital input-output modules, a PWM signal is generated on one of the digital input-output channels. The signal is read back on the same pin, then plotted using the matplotlib module.
{{ :test-and-measurement:analog-discovery-pro-3x50:digital_test.png?400 |}}
# import modules
import WaveForms_HAL as WF
import matplotlib.pyplot as plt
# define used digital pin
pin = 1
# define signal parameters
frequency = 50e03
duty_cycle = 30
try:
# initialize the interface
WF.initialize()
# initialize the logic analyzer with default settings
WF.logic.initialize()
# generate a signal
WF.pattern.generate(
pin, frequency, WF.pattern.type.pulse, duty_cycle=duty_cycle)
while True:
plt.plot(WF.logic.receive_data(pin)) # plot recorded signal
plt.show()
except KeyboardInterrupt:
pass
finally:
# close the device
WF.close()
<--
--> Testing the Pmod ALS: Test_PMOD_ALS.py #
To test the Pmod ALS, the ambient light intensity is read and displayed continuously.
# import modules
from PMOD import ALS
import WaveForms_HAL as WF
# define pins
ALS.pins.cs = 10
ALS.pins.sdo = 9
ALS.pins.sck = 8
try:
# initialize the interface
WF.initialize()
ALS.initialize(WF)
while True:
# display measurements
print(ALS.receive_percent())
except KeyboardInterrupt:
pass
finally:
# close the device
ALS.close()
WF.close()
<--
--> Testing the Pmod BLE: Test_PMOD_BLE.py #
To test the Pmod BLE, all messages received on Bluetooth are displayed, the string "got it" is sent as a response.
To be able to test the Pmod, download the [[https://play.google.com/store/apps/details?id=com.macdom.ble.blescanner|BLE Scanner]] application to your phone. Run the Python script, then start the application. It will ask you to turn on Bluetooth and location. After some time, you should see the Pmod BLE appearing in the scanner.
{{ :test-and-measurement:analog-discovery-pro-3x50:ble_test_device.jpeg?200 |}}
Note the long code (MAC address) below the name of the device. It will be important later.
Connect to it, then open **Custom Service** and tap the **N** (notify) icon in the first custom characteristic. You should see system messages appearing in the output stream of the Python script. Also, the "got it" message should appear at the custom characteristic. To send data, tap the **W** icon and type in your message.
{{ :test-and-measurement:analog-discovery-pro-3x50:ble_test_services.jpeg?200 |}}
Note the long code (UUID) of the service and the characteristic you are using. It will be important later.
# import modules
from PMOD import BLE
import WaveForms_HAL as WF
# define pins
BLE.pins.tx = 6
BLE.pins.rx = 5
BLE.pins.rst = 4
try:
# initialize the interface
WF.initialize()
BLE.initialize(WF)
BLE.reboot()
while True:
# receive data
data, sys_msg, error = BLE.receive_data()
# merge data and system messages
buf = ""
if len(data) > 0:
buf = data
elif len(sys_msg) > 0:
buf = sys_msg
# if the data is valid
if len(buf) > 0:
print(buf) # display it
BLE.send_data(" got it") # and send response
# if the data isn't valid
elif error != "no error":
print(error) # display the error
except KeyboardInterrupt:
pass
finally:
# close the device
BLE.reboot()
BLE.close()
WF.close()
<--
--> Testing the Pmod DA1: Test_PMOD_DA1.py #
Connect the oscilloscope channels of the ADP to the output channels of the Pmod DA1, then run the script. Enter voltage levels for each DAC channel, then compare them with the ones measured by the oscilloscope. Enter an "x" to finish the program.
# import modules
from PMOD import DA1
import WaveForms_HAL as WF
# define used pins
DA1.pins.sync = 3
DA1.pins.d0 = 2
DA1.pins.d1 = 1
DA1.pins.sck = 0
try:
# initialize the interface
WF.initialize()
DA1.initialize(WF)
# initialize the scope with default settings
WF.scope.initialize()
while True:
# read voltage from keyboard
voltage = input("Set voltage for A1: ")
# check exit condition
if voltage == "x":
break
# set voltage
DA1.output_voltage(DA1.output_channel.A1, float(voltage))
# display measured voltage levels
print([WF.scope.measure(1), WF.scope.measure(2), WF.scope.measure(3), WF.scope.measure(4)])
# read voltage from keyboard
voltage = input("Set voltage for B1: ")
# check exit condition
if voltage == "x":
break
# set voltage
DA1.output_voltage(DA1.output_channel.B1, float(voltage))
# display measured voltage levels
print([WF.scope.measure(1), WF.scope.measure(2), WF.scope.measure(3), WF.scope.measure(4)])
# read voltage from keyboard
voltage = input("Set voltage for A2: ")
# check exit condition
if voltage == "x":
break
# set voltage
DA1.output_voltage(DA1.output_channel.A2, float(voltage))
# display measured voltage levels
print([WF.scope.measure(1), WF.scope.measure(2), WF.scope.measure(3), WF.scope.measure(4)])
# read voltage from keyboard
voltage = input("Set voltage for B2: ")
# check exit condition
if voltage == "x":
break
# set voltage
DA1.output_voltage(DA1.output_channel.B2, float(voltage))
# display measured voltage levels
print([WF.scope.measure(1), WF.scope.measure(2), WF.scope.measure(3), WF.scope.measure(4)])
except KeyboardInterrupt:
pass
finally:
# close the device
DA1.close()
WF.close()
<--
--> Testing the Pmod KYPD: Test_PMOD_KYPD.py #
To test the keypad, read and display the pressed keys continuously.
# import modules
from PMOD import KYPD
import WaveForms_HAL as WF
# define pins
KYPD.pins.rows = [7, 6, 5, 4]
KYPD.pins.columns = [3, 2, 1, 0]
try:
# initialize the interface
WF.initialize()
KYPD.initialize(WF)
while True:
# display pressed keys
print(KYPD.receive_data())
except KeyboardInterrupt:
pass
finally:
# close the device
KYPD.close()
WF.close()
<--
--> Testing the Pmod OD1: Test_PMOD_OD1.py #
To test the open drain MOSFETs, connect the cathode (shorter lead) of some LEDs to the MOSFET drains. Connect one and of 470Ω resistors to the anodes (longer lead) of the LEDs. Connect the other lead of the resistors to the power supply output (red cable) on ADP.
The script turns on and off every LED one after the other, then repeats this step, but with the toggling function. When finished, enter duty cycles for every PWM signal commanding the MOSFETs to set the brightness of the LEDs. Finish the script by entering "x" instead of a duty cycle.
# import modules
from PMOD import OD1
import WaveForms_HAL as WF
import time
# define used pins
OD1.pins.g1 = 3
OD1.pins.g2 = 2
OD1.pins.g3 = 1
OD1.pins.g4 = 0
# define signal frequency
frequency = 1
# define PWM type
static_pwm = True
# require static testing
static_required = False
# define delay after operations
delay = 1 # in seconds
try:
# initialize the interface
WF.initialize()
OD1.initialize(WF)
if static_required:
# try the on/off functions
for index in range(1, 5):
OD1.on(index) # turn on MOSFET
print("on") # display message
time.sleep(delay) # wait
OD1.off(index) # turn off MOSFET
print("off") # display message
time.sleep(delay) # wait
# try the toggling function
for index in range(1, 5):
OD1.switch(index) # toggle MOSFET
print("toggle") # display message
time.sleep(delay) # wait
OD1.switch(index) # toggle MOSFET
print("toggle") # display message
time.sleep(delay) # wait
while True:
# read duty cycles from keyboard
duty = input("First MOSFET duty cycle: ")
# check exit condition
if duty == "x":
break
# test the pwm drive functions
OD1.drive(1, frequency, int(duty), static=static_pwm)
duty = input("Second MOSFET duty cycle: ")
if duty == "x":
break
OD1.drive(2, frequency, int(duty), static=static_pwm)
duty = input("Third MOSFET duty cycle: ")
if duty == "x":
break
OD1.drive(3, frequency, int(duty), static=static_pwm)
duty = input("Fourth MOSFET duty cycle: ")
if duty == "x":
break
OD1.drive(4, frequency, int(duty), static=static_pwm)
except KeyboardInterrupt:
pass
finally:
# turn off everything
OD1.off(1)
OD1.off(2)
OD1.off(3)
OD1.off(4)
# close the device
OD1.close()
WF.close()
<--
----
===== Building the Application =====
To build an Android application, the [[https://appinventor.mit.edu/|MIT App Inventor]] web application will be used. Open the site, create a new user, then start a new project. First, create the user interface of the application by drag and dropping user interface elements onto the virtual phone. Use the companion app on your real phone to see how the user interface will look. Alternatively, you can download and import the already created {{ :test-and-measurement:analog-discovery-pro-3x50:smart_lamp_project.zip |project file}}, or just download and install on your phone the final {{ :test-and-measurement:analog-discovery-pro-3x50:smart_lamp_app.zip |application}}.
For this application, a switch, three sliders, and several labels are needed. Use the //Horizontal Arrangement// and //Vertical Arrangement// blocks from the //Layout// menu to arrange everything on the screen.
When you are ready, find the //Extension// menu and import the [[https://appinventor2.droidim.com/mdocs-posts/bluetooth-low-energy-by-mit|Bluetooth Low Energy by MIT]] extension. Drag and drop a BLE component on the screen of the virtual phone.
{{ :test-and-measurement:analog-discovery-pro-3x50:app_builder_front.png?600 |}}
When you are finished with the user interface, enter Block view. Here use the puzzle pieces to create the logic backbone of your application. Define what happens when the user touches a slider/switch/label, when the Bluetooth module connects/disconnects/receives a message. Define what data do you want to send and how to decode the received information. If you have never created an application before, this is a great way to start.
Use comments on the pieces (small blue circles with a question mark) to make your "code" easy to understand.
In this editor, every separate puzzle piece runs as an interrupt. Use this to your advantage.
Hiding a component and invisible components can be useful. You can use an invisible error message, which is made visible only if an error appears, then hide it again using a timer interrupt, to display connection problems - this can be extremely useful during debugging.
To easily access the BLE device, service and characteristic you need, use the **MAC address**, **Service UUID** and **Characteristic UUID** obtained previously. If you don't have those, you can find the addresses by following this step: [[test-and-measurement:analog-discovery-pro-3x50:smart-lamp#testing_the_modules|Testing the Pmod BLE]].
{{ :test-and-measurement:analog-discovery-pro-3x50:app_builder_back.png?600 |}}
When you are ready, build the application and install it on your phone. To install it, you must enable installation from unknown sources. After installing the app, you might encounter warning messages from Google Play Protect, but just ignore them.
----
===== Hardware Setup =====
=== Connecting the PMODs ===
Connect the Pmod ALS, the Pmod BLE, the Pmod DA1, and one channel of the Pmod OD1 to the Analog Discovery Pro.
{{ :test-and-measurement:analog-discovery-pro-3x50:adp_pmods_bb.png?600 |}}
=== Building the PWM Generator ===
Connect three output channels of the Pmod DA1 to the inverting input of the comparators realized with the OP484 operational amplifier. To the non-inverting input, connect the second channel of the waveform generator. This circuit will create the PWM signals from the numerical data: the waveform generator outputs a sawtooth signal with 0.5V amplitude and 0.5V offset and this signal is compared to the voltage levels provided by the DAC so the rail-to-rail comparator generates logic levels according to the comparison result. The duty cycle of the resulting signal can be easily set: 0V on the DAC means 100% duty cycle, while 1V on the DAC means 0% duty cycle.
Connect the outputs of the comparators to the remaining MOSFET gates on the Pmod OD1.
{{ :test-and-measurement:analog-discovery-pro-3x50:pwm_generator_bb.png?600 |}}
To test the PWM generator circuit, you can connect an oscilloscope channel to the output of a comparator, then use WaveForms to generate the signal: first provide power to the Pmods by enabling the Supplies instrument, then generate the reference signal (sawtooth signal with 500mV offset and 500mV amplitude) on the second Wavegen channel. Use the SPI Master tool in the Protocol instrument to command the DAC and the Scope to display the generated signal. To generate the control voltages, use the command 0x03 to select channel A, or 0x07 to select channel B (the data line selects the DAC chip), then send the data word (a number between 0 - 0V and 77 - 0.99V). The duty cycle is set by the sent data word.
{{ :test-and-measurement:analog-discovery-pro-3x50:pwm_generator_test.png?600 |}}
=== Building the Charger Circuit ===
Use the Micro-USB plug to provide power to the battery charger. You can connect the charger to the back panel of the ADP. The charger consists of a programmable current sink, realized with the LT3092. The reference voltage will be provided by the first waveform generator channel of the ADP. The current sink can charge up the Li-Po cell until it reaches 4.2V. From here the cell would need a constant voltage source with decreasing current to get the topping charge, but to keep the circuit simple, this part won't be implemented.
To prevent the negative lead of the battery from becoming floating, the first MOSFET is used in the Pmod OD1 to couple it to the ground, when the charger isn't plugged in. A charge signaling LED is also connected to the ADP to provide feedback.
To be able to measure the voltage of the battery cell, connect the first oscilloscope channel to the negative lead of the battery and the second channel to the positive lead. As the scope channels have a common reference, the difference between the two measurements will give the battery voltage.
{{ :test-and-measurement:analog-discovery-pro-3x50:charger_circuit_bb.png?600 |}}
=== Connecting the RGB LED ===
Finally, connect the RGB LED (and the current limiting resistors calculated to your LED) between the positive lead of the battery and the remaining three MOSFETs of the Pmod OD1. In this circuit, only RGB LEDs with separate anodes and cathodes, or with a common anode and separate cathodes can be used.
{{ :test-and-measurement:analog-discovery-pro-3x50:rgb_led_bb.png?600 |}}
----
===== Software Setup =====
In the following, the structure of the main program file will be detailed. You can follow this guide to write your own control program based on the instructions given here, or you can download the source code {{ :test-and-measurement:analog-discovery-pro-3x50:lamp_controller.zip |here}}.
=== Importing the Modules and Defining Connections ===
To be able to use all the previously created modules, you must import them into your script.
To make your code more readable and easier to debug, it is good practice to name your connections (so you don't have to keep in mind which digital, or analog channel is used for what).
# import modules
from PMOD import DA1, BLE, ALS, OD1
import WaveForms_HAL as WF
import time
"""-------------------------------------------------------------------"""
# define connections
# PMOD DA1 pins
DA1.pins.sync = 3
DA1.pins.d0 = 2
DA1.pins.d1 = 1
DA1.pins.sck = 0
# Pmod OD1 pins
OD1.pins.g1 = 7
# PMOD BLE pins
BLE.pins.rst = 4
BLE.pins.rx = 5
BLE.pins.tx = 6
# PMOD ALS pins
ALS.pins.cs = 10
ALS.pins.sdo = 9
ALS.pins.sck = 8
# digital I/O
signal_LED = 11
# scope channels
battery_neg_ch = 1
battery_pos_ch = 2
# wavegen channels
current_reference = 1
pwm_reference = 2
# lamp color references
lamp_red = DA1.output_channel.A1
lamp_green = DA1.output_channel.B1
lamp_blue = DA1.output_channel.A2
# define low side switch (OD1 channel)
low_switch = 1
=== Global Variables and Auxiliary Functions ===
Define the global parameters of your project. If you initialize these variables at the start of your code, it will be easier to modify them during tuning the finished project.
Some auxiliary functions might be needed as well, which will be used later in the script.
# other parameters
light_referesh = 2 # delay between refreshing the light intensity (in seconds)
scope_average = 10 # how many measurements to average with the scope
light_average = 10 # how many measurements to average with the light sensor
battery_charged = 4.2 # battery charge level in volts
battery_discharged = 3.7 # battery discharge level in volts
max_charge_current = 0.1 # maximum charge current of the battery (in Amperes)
"""-------------------------------------------------------------------"""
def scale(value, source, destination):
# scale a number from a range to another
return ((value - source[0]) / (source[1] - source[0])) * (destination[1] - destination[0]) + destination[0]
The "body" of the script is inserted in a try-except structure. This structure runs the code sequence in the "try" block, and if an error (exception) occurs, handles it as defined in the "except" block. In this case the "except" block is empty (the script just finishes when the Ctrl+C combination is pressed), but it is followed by a "finally" block, which runs only once, when the try-except structure is exited. Here, the cleanup procedure can be executed, which will be discussed later.
=== Initialization ===
To be able to use the instruments, you must initialize the HAL created previously, as well as the modules controlling the PMODs. After everything is initialized, start generating the reference signals on the Wavegen channels, but turn off the lamp and the signaling LED. You can also make the battery ground floating, by turning off the MOSFET used as a low-side switch.
# initialize the interface
WF.initialize()
# initialize the scope with default settings
WF.scope.initialize()
# initialize the PMODs
DA1.initialize(WF)
OD1.initialize(WF)
ALS.initialize(WF)
BLE.initialize(WF)
BLE.reboot()
"""---------------------------------"""
# start generating the reference signals
WF.wavegen.generate(current_reference, WF.wavegen.type.dc, 0)
WF.wavegen.generate(pwm_reference, WF.wavegen.type.ramp.up,
0.5, frequency=1e03, offset=0.5, symmetry=100)
"""---------------------------------"""
# turn off the lamp
DA1.output_voltage(lamp_red, 1)
DA1.output_voltage(lamp_green, 1)
DA1.output_voltage(lamp_blue, 1)
# turn off the switch and the LED
WF.digital.set_output(signal_LED)
WF.digital.write(signal_LED, False)
OD1.off(low_switch)
=== Endless Loop ===
The main part of the script is run in an endless loop, which can be exited only by a keyboard interrupt. However, there are some states, which must be kept unchanged between iterations, so certain flags and variables must be initialized before the loop.
# variables to remember states
start_time = time.time()
lamp_on = False
off_flag = True
charger_connected = False
All other variables are temporal, they change in every iterations, so they can be defined in the loop.
# temporal variables
BT_flag = False
battery_negative = 0
battery_positive = 0
light = 0
=== Receive Data on Bluetooth Low Energy ===
As a first step, read the messages from the PMOD BLE and save the connection status (also turn off the lamp if the module is disconnected). If the data is received without error, convert the received bytes to voltages, then set the lamp color, by setting the output values of the DAC channels.
# read data from the Bluetooth module
data, sys_msg, error = BLE.receive_data()
data = list(data)
# turn the lamp on/off
if sys_msg.startswith("%CONNECT"):
lamp_on = True
elif sys_msg == "%DISCONNECT%":
lamp_on = False
# process the data
if error == "no error" and len(data) >= 3:
BT_flag = True
data = [ord(element) for element in data]
duty_red = scale(data[-3], [1, 255], [1, 0])
duty_green = scale(data[-2], [1, 255], [1, 0])
duty_blue = scale(data[-1], [1, 255], [1, 0])
# set lamp color according to received data
if lamp_on:
if BT_flag:
BT_flag = False
off_flag = False
DA1.output_voltage(lamp_red, duty_red)
DA1.output_voltage(lamp_green, duty_green)
DA1.output_voltage(lamp_blue, duty_blue)
else:
if not off_flag:
off_flag = True
DA1.output_voltage(lamp_red, 1)
DA1.output_voltage(lamp_green, 1)
DA1.output_voltage(lamp_blue, 1)
=== Measuring the Light Intensity ===
Light intensity is measured only after a predefined time interval. When it is needed, the PMOD ALS is used to measure the light intensity, then the result is encoded to a byte and sent using the Pmod BLE.
# if the light intensity has to be measured
if time.time() - start_time > light_referesh:
# reinitialize the SPI interface
ALS.initialize(WF)
# measure the light intensity
for _ in range(light_average):
light += ALS.receive_percent()
light /= light_average
# encode the light intensity
encoded_light = round(light * 2.55) & 0xFF
# reinitialize the UART interface
BLE.initialize(WF)
# send light intensity
BLE.send_data(encoded_light)
start_time = time.time()
=== Charging the Battery ===
In every iteration of the main loop, measure the battery voltage. Also check, whether the charger is connected, or not and turn on the low-side switch, if the charger is disconnected, to ground the battery properly, but turn off the switch, when the charger is connected, to prevent any overvoltage on the battery cell. Set the charging current and turn the signaling LED on, or off according to the state of the charger circuit.
# read battery voltage
for _ in range(scope_average):
battery_negative += WF.scope.measure(battery_neg_ch)
battery_negative /= scope_average
for _ in range(scope_average):
battery_positive += WF.scope.measure(battery_pos_ch)
battery_positive /= scope_average
battery_voltage = battery_positive - battery_negative
# decide if the charger is connected or not
if battery_positive >= 4.3:
charger_connected = True
OD1.off(low_switch)
else:
charger_connected = False
OD1.on(low_switch)
# calculate charge current reference
charge_current = max_charge_current * scale(battery_voltage, [battery_discharged, battery_charged], [0.5, 1])
charge_current_ref = scale(charge_current, [0, max_charge_current], [0, 1])
# start/stop charging
if charger_connected and battery_voltage < battery_charged:
WF.wavegen.generate(current_reference, WF.wavegen.type.dc, charge_current_ref)
WF.digital.write(signal_LED, True)
else:
WF.wavegen.generate(current_reference, WF.wavegen.type.dc, 0)
WF.digital.write(signal_LED, False)
=== Cleanup ===
When the script is finished, turn off the lamp and the charger, then close reset the used instruments and disconnect from the device.
# turn off the lamp
DA1.output_voltage(lamp_red, 1)
DA1.output_voltage(lamp_green, 1)
DA1.output_voltage(lamp_blue, 1)
# turn off the LED and the switch
WF.digital.write(signal_LED, False)
OD1.off(low_switch)
# close PMODs
ALS.close()
BLE.close()
DA1.close()
OD1.close()
# close device
WF.close()
----
===== Tuning and Testing =====
Start the script, then start the application on your phone. Wait until the phone discovers the PMOD BLE, then connect to it. Set the lamp color and luminosity on the sliders of the application.
If you want to modify the parameters of the script, stop it with Ctrl+C, modify the parameters, then restart the script. Averaging more measurements leads to a more stable result, with a slower update time.
Take care not to overcharge, or over-discharge the battery, or overload the power supply.
----
===== Next Steps =====
For more information on WaveForms SDK, see its [[software:waveforms:waveforms-sdk:start|Resource Center]].
For technical support, please visit the [[https://forum.digilentinc.com/forum/8-test-and-measurement/|Test and Measurement]] section of the Digilent Forums.