DIGILENT PmodAD2 Analog-to-Digital Converter User Manual
- June 12, 2024
- DIGILENT
Table of Contents
DIGILENT PmodAD2 Analog-to-Digital Converter
Overview
The PmodAD2 is an analog-to-digital converter powered by the Analog Devices AD7991. Users may communicate with the board through I2C to configure up to 4 conversion channels at 12 bits of resolution.
Features include
- 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)
- Follows Digilent Interface Specification
- Library and example code available in resource center
Functional Description
- The PmodAD2 utilizes Analog Devices® AD7991 to provide up to four channels of 12-bit analog-to-digital conversion.
Interfacing with the Pmod
- The PmodAD2 communicates with the host board via the 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.
Table 1. 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 PmodAD2 must be within 2.7V and 5.5V; however, it is recommended that the 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.
Contact
- 1300 Henley Court
- Pullman, WA 99163
- 509.334.6306
- www.digilentinc.com
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References
Read User Manual Online (PDF format)
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