Cross Triggering in WaveForms (Under Construction)

Connect the Digilent Test and Measurement device to the host computer.

Connect the analog input channel 1 positive pin (1+, orange cable) to the waveform generator output channel 1 pin (W1, yellow cable). Then connect the analog input channel 1 negative pin (1-, orange and white cable) to ground (down arrow, black cable). Lastly, connect the external trigger 1 pin (TRIG 1, grey cable) to the digital input/output pin 0 (DIO 0, pink cable).

The circuit achieved by these connections is a simple loopback, allowing the test and measurement device's waveform generator to provide a stimulus for its own oscilloscope, and to generate an external trigger with its digital I/O.

Launch WaveForms, then open the following instruments:

1. Open a new Wavegen instrument, then make the following changes to its configuration:
   • Set the Channel Synchronization to Independent
   • Set the Trigger source to Manual
   • Set the Wait time to none
   • Set the Run time to 1 ms
   • Set the Repeat count to infinite
   • Leave all other settings as their defaults
2. Open a new Scope instrument, then make the following changes to its configuration:
   • Set the Trigger Mode to Repeated and Normal
   • Set the Trigger Source to Wavegen 1
   • Ensure the Time Position is 0 s
   • Set the Time Base to 1 ms/div
   • Ensure Channel 1's Offset is 0 V
   • Ensure Channel 1's Range is 500 mV/div
   • Disable Channel 2 by unchecking its box
3. Open a new StaticIO instrument, then make the following change to its configuration:
   • Configure DIO 0 to be a button that outputs 0 when released, and 1 when pressed

Click the Manual Trigger button in the bottom left-hand corner of the WaveForms application (marked in red in the image to the right) to trigger the Wavegen instrument to output a signal once. The signal plays back so quickly that the Wavegen's state transition from Armed to Running back to Armed will probably not be seen. The Scope's state will go from Armed to Trig'd back to Armed, and the captured event will be displayed in the Scope's plot.

Next, try modifying the Wavegen trigger's Wait time field. Any value will work. Click the Manual Trigger button again. The Scope take another capture. Despite the changes, the captured signal will be placed at the same point in the plot. Modifying the Wavegen trigger's wait time also affects the Scope trigger: both instruments wait for that amount of time after the Manual Trigger to capture/generate the signal.

Next, change the Wavegen trigger's Source field to External 1. In the StaticIO instrument, click the button corresponding to DIO 0 (marked in red in the image to the right). Observe that this button has the same behavior as the Manual Trigger.

In conclusion, note that through each of these changes to the trigger configuration, the Scope trigger did not need to be reconfigured at all!

Further information regarding the trigger configuration options available in each instrument can be found in their respective “Using the …” guides (linked above), or through the WaveForms Reference Manual

Connect two Digilent Test and Measurement devices to the computer. Two Analog Discovery 2s were used in creating this document, but any WaveForms compatible device with analog inputs and outputs will work. If the devices require external power, plug them in and turn them on.

Make the following connections between the two devices' pins:

• Connect each device's analog input channel one positive pin (1+, orange cable) to the other device's waveform generator channel one pin (W1, yellow cable).
• Connect each device's analog input channel one negative pin (1-, orange and white cable) to a ground pin on either device (down arrow, black)
• Connect a ground pin from each device to a ground pin from the other device (down arrow, black).
• Connect each device's external trigger 1 pin (T1 or TRIG 1, grey cable) and digital output channel 1 pin (0 or DIO 0, pink cable) together, so that all four pins are connected to each other.

See the block diagram to the right for a visual representation of these connections.

Note: The connections are symmetrical, so it does not matter which device is considered “#1” and which is considered “#2”.

3. In one WaveForms instance, henceforth referred to as the “primary instance”, open the following instruments, and configure them as described:

• Open a new Scope instrument and apply the following changes to its configuration:
  • Time Base: 500us/div
  • Trigger Mode: Repeated / Normal
  • Trigger Source: External 1
  • Trigger Condition: Rising
  • Disable Channel 2
• Open a new Wavegen instrument and apply the following changes to its configuration:
  • Channel Synchronization: Independent
  • Channel 1 Trigger: External 1
  • Channel 1 Wait Time: none
  • Channel 1 Run Time: 2ms
  • Channel 1 Simple Wave Frequency: 1kHz
  • Channel 1 Simple Wave Type: Sine
• Open a new StaticIO instrument and apply the following changes to its configuration:
  • Configure DIO 0 to be a button that outputs 0 when released and 1 when pressed.
• Open a new Script instrument.

4. In the other WaveForms instance, henceforth referred to as the “secondary instance”, open the following instruments, and configure them as described:

• Open a new Scope instrument and apply the following changes to its configuration:
  • Time Base: 500us/div
  • Trigger Mode: Repeated / Normal
  • Trigger Source: External 1
  • Trigger Condition: Rising
  • Disable Channel 2
• Open a new Wavegen instrument and apply the following changes to its configuration:
  • Channel Synchronization: Independent
  • Channel 1 Trigger: External 1
  • Channel 1 Wait Time: none
  • Channel 1 Run Time: 2ms
  • Channel 1 Simple Wave Frequency: 1kHz
  • Channel 1 Simple Wave Type: Square
• Open a new Script instrument.

5. Copy the code to the right into the primary instance's Script instrument.

{
  // Create a reference channel to contain the imported acquisition
  var r = Scope.Ref1.Range.value
  var o = Scope.Ref1.Offset.value
  Scope.Ref1.Clone(Scope.Channel1) 
  Scope.Ref1.Range.value = r
  Scope.Ref1.Offset.value = o
  // Open the file exported by the secondary instance
  var f = File("1.bin")
  // Wait for the other instance to finish saving data
  for(var i = 0; i < 1000 && !f.exist(); i++);
  // Read data from the file and save it into the reference channel
  var rg = f.readDouble()
  f.deleteFile()
  Scope.Ref1.data = rg
}

6. Copy the code to the right into the secondary instance's Script instrument.

{
  // Create a binary file and write the channel 1 acquisition into it
  var f = File("1.bin")
  f.writeDouble(Scope.Channel1.alldata)
}

To capture data, first, click the Run button in each Scope and Wavegen instrument. Then, click the primary instance's StaticIO DIO 1 button to trigger all four instruments. Each device will play its wave for two milliseconds, which will then be captured by the other device's Scope. The results will look like the images to the right.

To view data captured by each device in the same plot, click the Run button in the secondary instance's Script instrument to export its captured data to a file. Then, click the Run button in the primary instance's Script instrument to import that data into its Scope as a Reference Channel. The result will look like the image to the right.