1 .. SPDX-License-Identifier: GPL-2.0 2 3 ============================= 4 AD525x Digital Potentiometers 5 ============================= 6 7 The ad525x_dpot driver exports a simple sysfs interface. This allows you to 8 work with the immediate resistance settings as well as update the saved startup 9 settings. Access to the factory programmed tolerance is also provided, but 10 interpretation of this settings is required by the end application according to 11 the specific part in use. 12 13 Files 14 ===== 15 16 Each dpot device will have a set of eeprom, rdac, and tolerance files. How 17 many depends on the actual part you have, as will the range of allowed values. 18 19 The eeprom files are used to program the startup value of the device. 20 21 The rdac files are used to program the immediate value of the device. 22 23 The tolerance files are the read-only factory programmed tolerance settings 24 and may vary greatly on a part-by-part basis. For exact interpretation of 25 this field, please consult the datasheet for your part. This is presented 26 as a hex file for easier parsing. 27 28 Example 29 ======= 30 31 Locate the device in your sysfs tree. This is probably easiest by going into 32 the common i2c directory and locating the device by the i2c slave address:: 33 34 # ls /sys/bus/i2c/devices/ 35 0-0022 0-0027 0-002f 36 37 So assuming the device in question is on the first i2c bus and has the slave 38 address of 0x2f, we descend (unrelated sysfs entries have been trimmed):: 39 40 # ls /sys/bus/i2c/devices/0-002f/ 41 eeprom0 rdac0 tolerance0 42 43 You can use simple reads/writes to access these files:: 44 45 # cd /sys/bus/i2c/devices/0-002f/ 46 47 # cat eeprom0 48 0 49 # echo 10 > eeprom0 50 # cat eeprom0 51 10 52 53 # cat rdac0 54 5 55 # echo 3 > rdac0 56 # cat rdac0 57 3
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.