Manual

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Revision: June 9, 2011
1300 NE Henley Court, Suite 3
Pullman, WA 99163
[phone] Voice | [phone] Fax
Doc: 502-217 page 1 of 2
Copyright Digilent, Inc. All rights reserved. Other product and company names mentioned may be trademarks of their respective owners.
Overview
The PmodAD2 is an analog to digital converter
module with up to 4 channels at 12-bit
resolution powered by the Analog Devices
AD7991.
Features include:
 Up to 4 analog to digital converter
channels
 Up to 12-bit resolution
 On-board 2.048V Voltage Reference
 Ability to choose the reference voltage
 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 4
analog inputs or up to 3 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 more details on read and write
procedures please view the AD7991
datasheet.
Device configuration is performed by writing to
the configuration register within the device.
This allows the user to choose which channels
are to be converting data, whether or not there
is an external reference voltage, and whether
or not there is bit trial or sample delay, for
more details please view the AD7991
datasheet. In order to read data from the
conversion result please consult the section
“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
PmodWifi