• AD7303

• PmodDA1

This is a Linux industrial I/O (IIO) subsystem driver, targeting single-channel serial interface DACs. The industrial I/O subsystem provides a unified framework for drivers for many different types of converters and sensors using a number of different physical interfaces (i2c, spi, etc). See IIO for more information.

Required devicetree properties:

• compatible: Needs to be “adi,” followed by the name of the device. E.g. “adi,ad5541a”
• reg: The chipselect number used for the device
• spi-max-frequency: Maximum SPI clock frequency
• Vdd-supply: VDD voltage supply regulator

Optional devicetree properties:

• REF-supply: external reference voltage supply regulator. This should only be set if there is an external reference voltage connected to the REF pin. If not set, Vdd/2 is used as the reference voltage.

       dac_vdd: fixedregulator@0 {
              compatible = "regulator-fixed";
              regulator-name = "fixed-supply";
              regulator-min-microvolt = <3300000>;
              regulator-max-microvolt = <3300000>;
              regulator-boot-on;
       };

       axi_spi_0: spi@42000000 {
              #address-cells = <1>;
              #size-cells = <0>;
              compatible = "xlnx,axi-spi-1.02.a", "xlnx,xps-spi-2.00.a";
               ...
              ad7303@0 {
                     compatible = "adi,ad7303";
                     reg = <0>;
                     spi-max-frequency = <1000000>;
                     Vdd-supply = <&dac_vdd>;
              };
        };

Description:
scale to be applied to out_voltage0_raw and out_voltage1_raw in order to obtain the measured voltage in millivolts.

root:/sys/bus/iio/devices/iio:device0> cat out_voltage_scale
12.890625

Description:
/sys/bus/iio/devices/iio:deviceX/out_voltageY_raw

Raw (unscaled, no bias etc.) output voltage for channel Y.

root:/sys/bus/iio/devices/iio:device0> echo 100 > out_voltage0_raw

U = out_voltage0_raw * out_voltage_scale = 100 * 12.890625 mV = 1289.0625 mV

/sys/bus/iio/devices/iio:deviceX/out_voltageY_powerdown

Description:
Writing 1 causes output Y to enter the power down mode. Clearing returns to normal operation.

root:/sys/bus/iio/devices/iio:device0> echo 1 > out_voltage0_powerdown
root:/sys/bus/iio/devices/iio:device0> cat out_voltage0_powerdown
1
root:/sys/bus/iio/devices/iio:device0> echo 0 > out_voltage0_powerdown
root:/sys/bus/iio/devices/iio:device0> cat out_voltage0_powerdown
0