Datasheet

PmodDA1™ Reference Manual
Copyright Digilent, Inc. All rights reserved.
Other product and company names mentioned may be trademarks of their respective owners.
Page 2 of 3
The PmodDA1 will receive its 8 bits of information from the system board through 16 clock cycles with first eight
bits consisting of eight control bits and the remaining eight bits representing the 8 bits of the data with the MSB
first. Each bit is received by the rising edge of the serial clock line. The function dictated by the first eight control
bits is executed when the chip select line is brought high.
A pinout table and diagram for the PmodDA1 are provided below:
Figure 1. PmodDA1 circuit diagram.
Table 1. Connector J1: Pin descriptions as labeled on the Pmod.
The on-board DACs can in principle use either an external or internal reference voltage; however, the PmodDA1 is
designed that the internal reference voltage of Vdd/2 volts must be used. Because of this, the first bit in the
command signal sent to the Pmod must always be a logic low signal in order to use the internal reference voltage
on the DAC. Tables describing the command signal and the associated bits from the AD7303 datasheet are
provided below.
Control Bits
Data Bits
~INT/EXT
X
LDAC
PDB
PDA
~A/B
CR1
CR0
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0
(MSB)
(LSB)
Table 2. PmodDA1 input shift register structure.
Note: The "~" signifies that the signal is active when driven low.
Header J1
Pin
Signal
Description
1
~SYNC
Chip Select (active low)
2
D0
Input Data 1
3
D1
Input Data 2
4
SCK
Serial Clock
5
GND
Power Supply Ground
6
VCC
Power Supply (3.3V/5V)
Header J2
Pin
Signal
Description
1
A1
Output Data A1
2
B1
Output Data B1
3
A2
Output Data A2
4
B2
Output Data B2
5
GND
Power Supply Ground
6
VCC
Positive Power Supply