- The Linux Foundation
- Mugilraj D
- Darius Berghe
- Dragos Bogdan
The project was to build a linux IIO driver for the AD5110 digital potentiometer and test it on hardware and send the code upstream. The driver support to read and write functionality to RDAC register which determines the wiper position and also it supports storing the wiper position to EEPROM memory for subsequent power-ups. This driver has the capability of auto-configuring of scale and offset based on the tolerance of each device this will give you accurate values.
Locate the device in your sysfs tree. This is probably easiest by going into the iio directory of sysfs tree or go to common i2c directory and locating the device by the i2c slave address.
root@analog:~# cat /sys/bus/iio/devices/iio\:device0/name
ad5110-10
root@analog:~# cat /sys/bus/i2c/devices/1-002f/iio\:device0/name
ad5110-10
Listing various attributes, IIO channels, etc. of AD5110 IIO device.
root@analog:~# ls /sys/bus/iio/devices/iio\:device0/
dev out_resistance_en out_resistance_scale uevent
name out_resistance_offset power store_eeprom
of_node out_resistance_raw subsystem
out_resistance_en
Writing '1' to enable the device and '0' to disable the device
root@analog:/sys/bus/iio/devices/iio:device0# echo 0 > out_resistance_en #disable
root@analog:/sys/bus/iio/devices/iio:device0# cat out_resistance_en
0
root@analog:/sys/bus/iio/devices/iio:device0# echo 1 > out_resistance_en #enable
root@analog:/sys/bus/iio/devices/iio:device0# cat out_resistance_en
1
out_resistance_raw
Read and write the wiper position to RDAC register.
root@analog:/sys/bus/iio/devices/iio:device0# echo 64 > out_resistance_raw
root@analog:/sys/bus/iio/devices/iio:device0# cat out_resistance_raw
64
root@analog:/sys/bus/iio/devices/iio:device0# echo 120 > out_resistance_raw
root@analog:/sys/bus/iio/devices/iio:device0# cat out_resistance_raw
120
out_resistance_offset
Read the offset value.
root@analog:/sys/bus/iio/devices/iio:device0# cat out_resistance_offset
0.884938271
out_resistance_scale
Read the scale value.
root@analog:/sys/bus/iio/devices/iio:device0# cat out_resistance_scale
79.101562500
store_eeprom
writing '1' to save the current wiper position from RDAC register to EEPROM memory. After power-up, the device will automatically load the saved configuration to RDAC. Read to find the saved wiper position.
root@analog:/sys/bus/iio/devices/iio:device0# cat out_resistance_raw
120
root@analog:/sys/bus/iio/devices/iio:device0# cat store_eeprom
64
root@analog:/sys/bus/iio/devices/iio:device0# echo 1 > store_eeprom
root@analog:/sys/bus/iio/devices/iio:device0# cat store_eeprom
120
- PR - Skeleton driver for AD5110 Digital potentiometer
Adds a basic driver skeleton for AD5110 (single channel, a Nonvolatile Digital Potentiometer). Along with the driver, this PR includes a device-tree overlay for AD5110 to use with Raspberry Pi 3 b+ and adds it to the device-tree's list of trivial devices.
Consists of commits as follows - - PR - iio: potentiometer: Add channel support to AD5110
Add the channel, read_raw(), and write_raw() functions support to the ad5110 driver with configured offset and scale. And added EEPROM support to hold the RDAC value.
Consists of commits as follows -
- [Patch v1] iio: potentiometer: Add driver support for AD5110
- [Patch v2] iio: potentiometer: Add driver support for AD5110
- [Patch v3] iio: potentiometer: Add driver support for AD5110
I would like to thank Darius Berghe and Dragos Bogdan for providing guidance and support throughout my project and also for sponsoring hardware. I would also like to thank Nuno Sá and other ADI members for providing suggestions and reviewing the code. Also thanks to Lars, Andy, and Jonathan for helping me to get accept my patch in IIO mailing list and to upstream it. I also like to thank my fellow participants Lucas and Puranjay for sharing their knowledge and their project..