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AD5677R NanDAC+IIO Linux驱动程序
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Table of Contents
nanoDAC+ IIO DAC Linux Driver
Supported Devices
This driver supports the
Reference Circuits
Evaluation Boards
Description
This is a Linux industrial I/O (IIO) subsystem driver, targeting multi-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.
Source Code
Status
Files
Devicetree
Required devicetree properties for spi devices:
- compatible: Needs to be the name of the device. E.g. “ad5676”
- reg: The chipselect number used for the device
- spi-max-frequency: Maximum SPI clock frequency.
- spi-cpol: Needs to be set for the correct SPI mode
- vcc-supply: Phandle to the fixed regulator
- interrupts: the interrupt used for buffer sampling
- pwms: pwm pin used as the interrupt source
adc_vref: fixedregulator@0 {
compatible = "regulator-fixed";
regulator-name = "fixed-supply";
regulator-min-microvolt = <2500000>;
regulator-max-microvolt = <2500000>;
regulator-boot-on;
};
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
ad5676@0 {
compatible = "ad5676";
reg = <0>;
spi-max-frequency = <1000000>;
spi-cpha;
vcc-supply = <&adc_vref>;
interrupts = <25 IRQ_TYPE_EDGE_RISING>;
interrupt-parent = <&gpio>;
pwms = <&pwm 0 100>;
pwm-names = "pwm-trigger";
};
Required devicetree properties for i2c devices:
- compatible: Needs to be the name of the device. E.g. “AD5696”
- reg: The chipselect number used for the device
- vcc-supply: Phandle to the fixed regulator
- interrupts: the interrupt used for buffer sampling
- pwms: pwm pin used as the interrupt source
adc_vref: fixedregulator@0 {
compatible = "regulator-fixed";
regulator-name = "fixed-supply";
regulator-min-microvolt = <2500000>;
regulator-max-microvolt = <2500000>;
regulator-boot-on;
};
#address-cells = <1>;
#size-cells = <0>;
status = "okay";
ad5696@e {
compatible = "ad5696";
reg = <0xe>;
vcc-supply = <&adc_vref>;
interrupts = <25 IRQ_TYPE_EDGE_RISING>;
interrupt-parent = <&gpio>;
pwms = <&pwm 0 100>;
pwm-names = "pwm-trigger";
};
Driver testing
This specifies any shell prompt running on the target
root:/> cd /sys/bus/iio/devices/ root:/sys/bus/iio/devices> ls iio:device0 root:/sys/bus/iio/devices> cd iio/:device0 root:/sys/bus/iio/devices/iio:device0> ls -l drwxr-xr-x 2 root root 0 Jul 31 15:17 buffer -r--r--r-- 1 root root 4096 Jul 31 15:17 dev -r--r--r-- 1 root root 4096 Jul 31 15:17 name lrwxrwxrwx 1 root root 0 Jul 31 15:17 of_node -> ../../../../../../../../firmware/devicetree/base/soc/spi@7e204000/ad5679r@0 -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage0_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage0_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage0_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage10_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage10_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage10_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage11_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage11_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage11_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage12_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage12_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage12_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage13_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage13_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage13_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage14_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage14_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage14_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage15_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage15_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage15_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage1_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage1_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage1_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage2_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage2_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage2_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage3_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage3_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage3_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage4_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage4_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage4_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage5_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage5_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage5_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage6_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage6_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage6_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage7_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage7_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage7_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage8_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage8_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage8_raw -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage9_powerdown -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage9_powerdown_mode -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage9_raw -r--r--r-- 1 root root 4096 Jul 31 15:17 out_voltage_powerdown_mode_available -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage_sampling_frequency -rw-r--r-- 1 root root 4096 Jul 31 15:17 out_voltage_scale drwxr-xr-x 2 root root 0 Jul 31 15:17 power drwxr-xr-x 2 root root 0 Jul 31 15:17 scan_elements lrwxrwxrwx 1 root root 0 Jul 31 15:17 subsystem -> ../../../../../../../../bus/iio drwxr-xr-x 2 root root 0 Jul 31 15:17 trigger -rw-r--r-- 1 root root 4096 Jul 31 15:17 uevent
Show device name
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat name ad5696
Show scale
Description:
scale to be applied to in_voltage0_raw in order to obtain the measured voltage in millivolts.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat out_voltage_scale 0.038146972
Set channel Y output voltage
Description:
/sys/bus/iio/devices/deviceX/out_voltageY_raw
Raw (unscaled, no bias etc.) output voltage for channel Y.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> echo 10000 > out_voltage0_raw
U = out_voltage0_raw * out_voltage_scale = 10000 * 0.038140 = 381.40 mV
List available power down modes
/sys/bus/iio/devices/deviceX/out_powerdown_mode_available
Description:
Lists all available output power down modes.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat out_voltage_powerdown_mode_available 1kohm_to_gnd 100kohm_to_gnd three_state
Set channel Y power down mode
/sys/bus/iio/devices/deviceX/out_voltageY_powerdown_mode
Description:
Specifies the output power down mode.
DAC output stage is disconnected from the amplifier and
| 1kohm_to_gnd | connected to ground via an 1kOhm resistor |
| 100kohm_to_gnd | connected to ground via an 100kOhm resistor |
| three_state | left floating |
For a list of available output power down options read out_voltageX_powerdown_mode_available.
This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> echo three_state > out_voltage0_powerdown_mode root:/sys/bus/iio/devices/iio:device0> cat out_voltage0_powerdown_mode three_state
Enable power down mode on output Y
/sys/bus/iio/devices/deviceX/out_voltageY_powerdown
Description:
Writing 1 causes output Y to enter the power down mode specified
by the corresponding out_voltageY_powerdown_mode. Clearing returns to
normal operation. Y may be suppressed if all outputs are
controlled together.
This specifies any shell prompt running on the target
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
Buffer Support
Description:
The nanoDAC family of devices has buffer support for changing the output of the DAC channels. To achieve this a PWM signal is used as the device trigger to output data. Using a sampling frequency attribute the period of the PWM signal can be changed. The sampling frequency is in Hz.
This specifies any shell prompt running on the target
root@analog:/sys/bus/iio/devices/iio:device0 $ cat out_voltage_sampling_frequency 1000 root@analog:/sys/bus/iio/devices/iio:device0# echo 2000 > out_voltage_sampling_frequency root@analog:/sys/bus/iio/devices/iio:device0# cat out_voltage_sampling_frequency 2000
Enable buffered channels
Description:
The user has to enable on what channels to output the buffer samples. The samples are interleaved in the following in the order of the enabled channels.
Example:
If only channel 1 is enabled the buffer samples will have the following configuration:
This specifies any shell prompt running on the target
root@analog:/sys/bus/iio/devices/iio:device0# cd scan_elements/ root@analog:/sys/bus/iio/devices/iio:device0/scan_elements# ls out_voltage0_en out_voltage10_type out_voltage12_index out_voltage14_en out_voltage15_type out_voltage2_index out_voltage4_en out_voltage5_type out_voltage7_index out_voltage9_en out_voltage0_index out_voltage11_en out_voltage12_type out_voltage14_index out_voltage1_en out_voltage2_type out_voltage4_index out_voltage6_en out_voltage7_type out_voltage9_index out_voltage0_type out_voltage11_index out_voltage13_en out_voltage14_type out_voltage1_index out_voltage3_en out_voltage4_type out_voltage6_index out_voltage8_en out_voltage9_type out_voltage10_en out_voltage11_type out_voltage13_index out_voltage15_en out_voltage1_type out_voltage3_index out_voltage5_en out_voltage6_type out_voltage8_index out_voltage10_index out_voltage12_en out_voltage13_type out_voltage15_index out_voltage2_en out_voltage3_type out_voltage5_index out_voltage7_en out_voltage8_type root@analog:/sys/bus/iio/devices/iio:device0/scan_elements# echo 1 > out_voltage0_en root@analog:/sys/bus/iio/devices/iio:device0/scan_elements# cd ../buffer/ root@analog:/sys/bus/iio/devices/iio:device0/buffer# ls data_available enable length watermark root@analog:/sys/bus/iio/devices/iio:device0/buffer# echo 1 > enable
Sending a buffer sample example:
This specifies any shell prompt running on the target
root@analog:/sys/bus/iio/devices/iio:device0/buffer# echo -n -e '/x22/x33' > /dev/iio/:device0
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
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