Digilent 410-217P - Manual

P P m m o o d d A A D D 2 2 ™ ™ R R e e f f e e r r e e n n c c e e M M a a n n u u a a l l
Revision: August 30, 2011
Note: This document applies to REV A of the board.
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Overview
The PmodAD2 is an analog-to-digital converter
module with up to four channels at 12-bit
resolution powered by the Analog Devices
AD7991.
Features include:
•
up to four analog to digital converter
channels
•
up to 12-bit resolution
•
on-board 2.048V voltage reference
•
ability to choose the voltage reference
•
I 2 C interface
Functional Description
The PmodAD2 uses an 8-pin connector that
allows communication via I
2 C. The PmodAD2
also has a 6-pin connector that allows up to
four analog inputs or up to three analog inputs
and a voltage reference.
Interface
All communications with the device must
specify a device address and a flag indicating
whether the communication is a read or a
write. This is followed by the actual data
transfer. For details on read and write
procedures please see the AD7991 datasheet.
Device configuration is performed by writing to
the configuration register within the device.
This allows you to choose which channels are
converting data, whether or not there is an
external reference voltage, and whether or not
there is bit trial or sample delay.
To read data from the conversion result, see
“Reading from the AD7991/AD7995/AD7999”
in the AD7991 datasheet.
The I
2 C interface standard uses two signal
lines. These are I
2
C data (SDA) and I
2
C clock
(SCL). These signals map to the serial data
(SDA) and serial clock (SCL), respectively, on
the AD7991.
Connector J1 – I2C Communications
Pin
Signal Description
1, 2 SCL I2C Clock
3, 4 SDA I2C Data
5, 6 GND Power Supply Ground
7, 8 VCC Power Supply (3.3V)
Interface Connector Signal Description