This version (29 Feb 2024 15:58) was approved by Ana-Maria Cusco.
Table of Contents
AD4170 24-Bit Sigma-Delta ADC with Integrated PGA Linux Driver
Supported Devices
This driver supports the
Evaluation Boards
Description
This is a Linux industrial I/O (IIO) subsystem driver, targeting single channel serial interface ADCs. 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.
Status
| Source |
|---|
| repo>linux/tree/dev_ad4170 |
Files
| Function | File |
|---|---|
| driver | ad4170.c |
Driver testing
Each and every IIO device, typically a hardware chip, has a device folder under /sys/bus/iio/devices/iio:deviceX. Where X is the IIO index of the device. Under every of these directory folders reside a set of files, depending on the characteristics and features of the hardware device in question. These files are consistently generalized and documented in the IIO ABI documentation. In order to determine which IIO deviceX corresponds to which hardware device, the user can read the name file /sys/bus/iio/devices/iio:deviceX/name. In case the sequence in which the iio device drivers are loaded/registered is constant, the numbering is constant and may be known in advance.
TIP: An example program which uses the interface can be found here:
<WRAP box bggreen>This specifies any shell prompt running on the target
root@analog:~# cd /sys/bus/iio/devices/ root@analog:/sys/bus/iio/devices# ls iio:device0 trigger0 root@analog:/sys/bus/iio/devices# cd iio\:device0 root@analog:/sys/bus/iio/devices/iio:device0# ls -l total 0 drwxr-xr-x 2 root root 0 Sep 13 08:09 buffer -r--r--r-- 1 root root 4096 Sep 13 08:09 dev -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_calibbias -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_calibscale -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_filter_type -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_offset -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_raw -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_sampling_frequency -r--r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_sampling_frequency_available -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_scale -r--r--r-- 1 root root 4096 Sep 13 08:09 in_voltage0-voltage24_scale_available -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_calibbias -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_calibscale -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_filter_type -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_offset -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_raw -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_sampling_frequency -r--r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_sampling_frequency_available -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_scale -r--r--r-- 1 root root 4096 Sep 13 08:09 in_voltage29-voltage24_scale_available -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_calibbias -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_calibscale -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_filter_type -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_offset -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_raw -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_sampling_frequency -r--r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_sampling_frequency_available -rw-r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_scale -r--r--r-- 1 root root 4096 Sep 13 08:09 in_voltage3-voltage4_scale_available -r--r--r-- 1 root root 4096 Sep 13 08:09 in_voltage-voltage_filter_type_available -r--r--r-- 1 root root 4096 Sep 13 08:09 name lrwxrwxrwx 1 root root 0 Sep 13 08:09 of_node -> ../../../../../../../../firmware/devicetree/base/soc/spi@7e204000/ad4170@0 drwxr-xr-x 2 root root 0 Sep 13 08:09 power drwxr-xr-x 2 root root 0 Sep 13 08:09 scan_elements lrwxrwxrwx 1 root root 0 Sep 13 08:09 subsystem -> ../../../../../../../../bus/iio drwxr-xr-x 2 root root 0 Sep 13 08:09 trigger -rw-r--r-- 1 root root 4096 Sep 13 08:09 uevent
Show device name
<WRAP box bggreen>This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat name ad4170
Show channel scale, offset, sampling_frequency, calibbias, calibscale
Description:
Scale, offset, calibbias, calibscale, sampling frequency for the in_voltagex_voltagey channel
<WRAP box bggreen>This specifies any shell prompt running on the target
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_scale
0.000149011
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_offset
0
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_raw
16777216
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_calibbias
0
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_calibscale
0
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_sampling_frequency
125000.000000000
Description:
Channel Ainp29-Ainm24 is configured as unipolar, with a gain of 1
U = in_voltage29-voltage24_raw * in_voltage29-voltage24_scale - in_voltage29-voltage24_offset = 16777216* 0.000149011 - 0 = 2499.98 mV
Show channel scale_available and sampling_frequency_available
Description:
Scales and sampling rates to be applied to the channel.
<WRAP box bggreen>This specifies any shell prompt running on the target
<xterm>
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_scale_available
0.000149011 0.000074505 0.000037252 0.000018626 0.000009313 0.000004656 0.000002328 0.000001164 0.000298023 0.000149011
root:/sys/bus/iio/devices/iio:device0> cat in_voltage29-voltage24_sampling_frequency_available
[7.629860220 15.259720441 125000.000000000]
Show filter_type_available
root:/sys/bus/iio/devices/iio:device0> cat in_voltage-voltage_filter_type_available sinc5+avg sinc5 sinc3
Device Tree
ad4170@0 {
compatible = "adi,ad4170";
reg = <0>;
avdd-supply = <&avdd>;
#address-cells = <1>;
#size-cells = <0>;
spi-max-frequency = <5000000>;
interrupts = <25 IRQ_TYPE_EDGE_FALLING>;
interrupt-parent = <&gpio>;
interrupt-names = "adc_rdy";
adi,dig-aux1-function = "rdy";
adi,gpio0-power-down-switch;
adi,gpio1-power-down-switch;
channel@0 {
reg = <0>;
adi,reference-select = <AD4170_REFIN_REFOUT>;
/* REFOUT, DGND */
diff-channels = <29 24>;
adi,chop-iexc = <AD4170_CHOP_IEXC_OFF>;
adi,chop-adc = <AD4170_CHOP_ACX_2PIN>;
};
channel@1 {
reg = <1>;
adi,reference-select = <2>;
/* AIN0, DGND */
diff-channels = <0 24>;
bipolar;
};
channel@2 {
reg = <2>;
adi,reference-select = <2>;
/* AIN3+, AIN4- */
diff-channels = <3 4>;
bipolar;
};
}
The adi,gpio0-power-down-switch and adi,gpio1-power-down-switch properties enable the power down switches on GPIO0 and GPIO1 repectively.
AC excitation is controlled via adi,chop_iexc and adi,chop_adc properties and can use 2 or 4 gpio pins.
More Information
- IIO mailing list: linux [dash] iio [at] vger [dot] kernel [dot] org
resources/tools-software/linux-drivers/iio-adc/ad4170.txt · Last modified: 29 Feb 2024 13:53 by Ana-Maria Cusco