Kernel driver ina2xx

Supported chips:

  • Texas Instruments INA219

    Prefix: ‘ina219’ Addresses: I2C 0x40 - 0x4f

    Datasheet: Publicly available at the Texas Instruments website

  • Texas Instruments INA220

    Prefix: ‘ina220’

    Addresses: I2C 0x40 - 0x4f

    Datasheet: Publicly available at the Texas Instruments website

  • Texas Instruments INA226

    Prefix: ‘ina226’

    Addresses: I2C 0x40 - 0x4f

    Datasheet: Publicly available at the Texas Instruments website

  • Texas Instruments INA230

    Prefix: ‘ina230’

    Addresses: I2C 0x40 - 0x4f

    Datasheet: Publicly available at the Texas Instruments website

  • Texas Instruments INA231

    Prefix: ‘ina231’

    Addresses: I2C 0x40 - 0x4f

    Datasheet: Publicly available at the Texas Instruments website

Author: Lothar Felten <lothar.felten@gmail.com>

Description

The INA219 is a high-side current shunt and power monitor with an I2C interface. The INA219 monitors both shunt drop and supply voltage, with programmable conversion times and filtering.

The INA220 is a high or low side current shunt and power monitor with an I2C interface. The INA220 monitors both shunt drop and supply voltage.

The INA226 is a current shunt and power monitor with an I2C interface. The INA226 monitors both a shunt voltage drop and bus supply voltage.

INA230 and INA231 are high or low side current shunt and power monitors with an I2C interface. The chips monitor both a shunt voltage drop and bus supply voltage.

The shunt value in micro-ohms can be set via platform data or device tree at compile-time or via the shunt_resistor attribute in sysfs at run-time. Please refer to the Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml for bindings if the device tree is used.

Additionally ina226 supports update_interval attribute as described in Naming and data format standards for sysfs files. Internally the interval is the sum of bus and shunt voltage conversion times multiplied by the averaging rate. We don’t touch the conversion times and only modify the number of averages. The lower limit of the update_interval is 2 ms, the upper limit is 2253 ms. The actual programmed interval may vary from the desired value.

General sysfs entries

in0_input Shunt voltage(mV) channel
in1_input Bus voltage(mV) channel
curr1_input Current(mA) measurement channel
power1_input Power(uW) measurement channel
shunt_resistor Shunt resistance(uOhm) channel

Sysfs entries for ina226, ina230 and ina231 only

in0_lcrit Critical low shunt voltage
in0_crit Critical high shunt voltage
in0_lcrit_alarm Shunt voltage critical low alarm
in0_crit_alarm Shunt voltage critical high alarm
in1_lcrit Critical low bus voltage
in1_crit Critical high bus voltage
in1_lcrit_alarm Bus voltage critical low alarm
in1_crit_alarm Bus voltage critical high alarm
power1_crit Critical high power
power1_crit_alarm Power critical high alarm
update_interval data conversion time; affects number of samples used to average results for shunt and bus voltages.

Note

  • Configure shunt_resistor before configure power1_crit, because power value is calculated based on shunt_resistor set.
  • Because of the underlying register implementation, only one *crit setting and its alarm can be active. Writing to one *crit setting clears other *crit settings and alarms. Writing 0 to any *crit setting clears all *crit settings and alarms.