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pmod:pmodad2:reference-manual [2022/06/09 18:29] – Marthapmod:pmodad2:reference-manual [2022/10/04 11:38] (current) – external edit 127.0.0.1
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 +====== Pmod AD2 Reference Manual ======
  
 +<WRAP round important 660px>
 +The Pmod AD2 is now retired and no longer for sale in our store.
 +</WRAP>
 +
 +The Digilent %%Pmod AD2%% (Revision A) is a four channel, 12-bit analog-to-digital converter powered by the [[http://www.analog.com/static/imported-files/data_sheets/AD7991_7995_7999.pdf|AD7991]] from Analog Devices.
 +
 +{{Digilent Image Gallery 
 +| image = {{:reference:pmod:pmodad2:pmodad2-0.png?direct |}}
 +| image = {{:reference:pmod:pmodad2:pmodad2-1.png?direct |}}
 +| image = {{:reference:pmod:pmodad2:pmodad2-2.png?direct |}}
 +| image = {{:reference:pmod:pmodad2:pmodad2-3.png?direct |}}
 +}} 
 +
 +
 +== Download This Reference Manual == 
 +  * {{:reference:pmod:pmodad2:pmodad2_rm.pdf| PDF}}
 +
 +----
 +
 +===== Features =====
 +  * Up to four 12-bit analog to digital converter channels
 +  * On-board 2.048 V voltage reference
 +  * Jumper selectable reference input
 +  * Small PCB size for flexible designs 1.0 in × 0.8 in (2.5 cm × 2.0 cm)
 +  * 2x4-pin connector with I2C interface
 +  * Library and example code available in resource center
 +
 +
 +
 +
 +----
 +=====Functional Description =====
 +The %%Pmod AD2%% utilizes [[http://www.analog.com/static/imported-files/data_sheets/AD7991_7995_7999.pdf|Analog Devices 
 +AD7991]] to provide up to four channels of 12-bit analog-to-digital conversion. 
 +
 +----
 +===== Interfacing with the Pmod=====
 +The %%Pmod AD2%% communicates with the host board via the [[pmod:communication_protocols:i2c|I²C protocol]]. System boards are able to call the Pmod by sending out the device address of 0b0101000 followed by the appropriate read or write bit. If a write bit is chosen, users may then configure the on-board chip to only use certain channels or may immediately start reading the 12 bits of data from the 16 bit data register if the read bit is sent. 
 +
 +Unlike other devices that use I²C no addresses are associated with these two registers; only the read/write bit at the end of the slave address distinguishes between the two registers. By default all four channels have analog-to-digital conversions performed on them sequentially with the supply voltage VCC acting as the voltage reference for the %%ADC%%.
 +
 +After each conversion is performed, the device places itself into power-down mode. Upon a read command, the device will wake itself up and prepare for a conversion which takes approximately 0.6 μs. The actual conversion process takes approximately 1.0 μs.
 +
 +==== Pinout Description Table ====
 +^  Pin  ^  Signal  ^  Description             ^
 +|  1 & 5   |  SCL  |  Serial Clock            |
 +|  2 & 6   |  SDA  |  Serial Data             |
 +|  3 & 7   |  GND  |  Power Supply Ground     |
 +|  4 & 8   |  VCC  |  Power Supply (3.3V/5V)  |
 +
 +Any external power applied to the %%Pmod AD2%% must be within 2.7V and 5.5V; however, it is recommended that Pmod is operated at 3.3V.
 +----
 +===== Physical Dimensions =====
 +The pins on the pin header are spaced 100 mil apart. The PCB is 1 inch long on the sides parallel to the pins on the pin header and 0.8 inches long on the sides perpendicular to the pin header.
 +----
 +===== Additional Information =====
 +The schematics of the %%Pmod AD2%% are available {{reference:pmod:pmodad2:pmodad2_sch.pdf|here}}. Additional information about the %%ADC%% including communication modes and specific timings of the chip can be found by checking out its datasheet [[http://www.analog.com/static/imported-files/data_sheets/AD7991_7995_7999.pdf|here]]. 
 +
 +Example code demonstrating how to get information from the %%Pmod AD2%% can be found [[pmod:pmodad2:start#example_projects|here]]. 
 +
 +If you have any questions or comments about the %%Pmod AD2%%, feel free to post them under the appropriate section ("Add-on Boards") of the [[https://forum.digilentinc.com/|Digilent Forum]].