1--------------------------------- 2 AD525x Digital Potentiometers 3--------------------------------- 4 5The ad525x_dpot driver exports a simple sysfs interface. This allows you to 6work with the immediate resistance settings as well as update the saved startup 7settings. Access to the factory programmed tolerance is also provided, but 8interpretation of this settings is required by the end application according to 9the specific part in use. 10 11--------- 12 Files 13--------- 14 15Each dpot device will have a set of eeprom, rdac, and tolerance files. How 16many depends on the actual part you have, as will the range of allowed values. 17 18The eeprom files are used to program the startup value of the device. 19 20The rdac files are used to program the immediate value of the device. 21 22The tolerance files are the read-only factory programmed tolerance settings 23and may vary greatly on a part-by-part basis. For exact interpretation of 24this field, please consult the datasheet for your part. This is presented 25as a hex file for easier parsing. 26 27----------- 28 Example 29----------- 30 31Locate the device in your sysfs tree. This is probably easiest by going into 32the 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 37So assuming the device in question is on the first i2c bus and has the slave 38address of 0x2f, we descend (unrelated sysfs entries have been trimmed). 39 40 # ls /sys/bus/i2c/devices/0-002f/ 41 eeprom0 rdac0 tolerance0 42 43You 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 58