410-245P-KIT Digilent

1300 Henley Court Pullman, WA 99163 509.334.6306 www.digilentinc.com PmodDA4 Reference Manual Revised May 24, 2016 This manual applies to the PmodDA4 rev. B Overview The Digilent PmodDA4 is an octal, 12-bit digital-to-analog converter module. Features include: Eight channel, 12-bit DAC Capable of eight simultaneous outputs High-speed DSP compatible Power-down function capability Low power consumption Small PCB size for flexible designs 1.2 0.8 (3.0 cm 2.0 cm) 6-pin Pmod connector with SPI interface Follows Digilent Interface Specification Type 2 Example code available in resource center The PmodDA4. 1 Functional Description The PmodDA4 utilizes Analog Devices AD5628 to provide a signal DAC capable of 8 simultaneous output channels. With its internal reference voltage of 2.5V, a resolution of approximately 1 mV can be achieved. 2 Interfacing with the Pmod The PmodDA4 communicates with the host board via the SPI protocol. By driving the Chip Select (CS) line to a logic level low voltage, users may send a series of 32 bits of information with the data clocked into the appropriate register on the falling edge of the Serial Clock (SCLK). Once the 32nd bit of information has been clocked in, the command that was sent in the data stream is executed. An example data stream of how the 32 bits are to be sent to the module is provided below from the AD5628 datasheet. Copyright Digilent, Inc. All rights reserved. DOC : 502-245 Page 1 of 3 Other product and company names mentioned may be trademarks of their respective owners. PmodDA4 Reference Manual DB31 (MSB) Command Bits Address Bits X X X X C3 C2 C1 C0 A3 A2 A1 A0 Data Bits D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 DB0 (LSB) X X X X X X X X Table 1. Example data stream from the AD5628 datasheet. Users should note that the PmodDA4 by default attempts to use an external reference voltage. However, as there is no external reference voltage provided on the Pmod, users must write to the register to program the chip to use its internal reference voltage of 2.5V. The data stream required to change this is provided below: Internal REF Register (DB0) Action 0 Reference off (default) 1 Reference on Table 2. Internal reference register from the AD5628 datasheet (table 10). DB31 to DB28 DB27 DB26 DB25 DB24 X 1 0 0 0 Don t Cares Command bits (C3 to C0) DB23 DB22 DB21 DB20 DB19 to DB1 DB0 X X X X X 1/0 Internal REF Address bits (A3 to A0) - don t cares Don t cares register Table 3. 32-bit input shift register contents for reference set-up command from the AD5628 datasheet (table 11). The various commands and addresses available for the on-board AD5628 can be found on page 22 of its datasheet. 2.1 Pinout Description Table Pin Signal Description 1 ~CS Chip Select 2 MOSI Master-Out-Slave-In 3 (NC) Not Connected 4 SCLK Serial Clock 5 GND Power Supply Ground 6 VCC Power Supply (3.3V/5V) Any external power applied to the PmodDA4 must be within 2.7V and 5.5V however, it is recommended that Pmod is operated at 3.3V. Copyright Digilent, Inc. All rights reserved. Page 2 of 3 Other product and company names mentioned may be trademarks of their respective owners.