4-Channel 12-bit A/D Converter
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.
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.
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.