LXR linux/Documentation/hwmon/ina2xx.rst

   1Kernel driver ina2xx
   2====================
   3
   4Supported chips:
   5
   6  * Texas Instruments INA219
   7
   8
   9    Prefix: 'ina219'
  10    Addresses: I2C 0x40 - 0x4f
  11
  12    Datasheet: Publicly available at the Texas Instruments website
  13
  14               https://www.ti.com/
  15
  16  * Texas Instruments INA220
  17
  18    Prefix: 'ina220'
  19
  20    Addresses: I2C 0x40 - 0x4f
  21
  22    Datasheet: Publicly available at the Texas Instruments website
  23
  24               https://www.ti.com/
  25
  26  * Texas Instruments INA226
  27
  28    Prefix: 'ina226'
  29
  30    Addresses: I2C 0x40 - 0x4f
  31
  32    Datasheet: Publicly available at the Texas Instruments website
  33
  34               https://www.ti.com/
  35
  36  * Texas Instruments INA230
  37
  38    Prefix: 'ina230'
  39
  40    Addresses: I2C 0x40 - 0x4f
  41
  42    Datasheet: Publicly available at the Texas Instruments website
  43
  44               https://www.ti.com/
  45
  46  * Texas Instruments INA231
  47
  48    Prefix: 'ina231'
  49
  50    Addresses: I2C 0x40 - 0x4f
  51
  52    Datasheet: Publicly available at the Texas Instruments website
  53
  54               https://www.ti.com/
  55
  56Author: Lothar Felten <lothar.felten@gmail.com>
  57
  58Description
  59-----------
  60
  61The INA219 is a high-side current shunt and power monitor with an I2C
  62interface. The INA219 monitors both shunt drop and supply voltage, with
  63programmable conversion times and filtering.
  64
  65The INA220 is a high or low side current shunt and power monitor with an I2C
  66interface. The INA220 monitors both shunt drop and supply voltage.
  67
  68The INA226 is a current shunt and power monitor with an I2C interface.
  69The INA226 monitors both a shunt voltage drop and bus supply voltage.
  70
  71INA230 and INA231 are high or low side current shunt and power monitors
  72with an I2C interface. The chips monitor both a shunt voltage drop and
  73bus supply voltage.
  74
  75The shunt value in micro-ohms can be set via platform data or device tree at
  76compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
  77refer to the Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml for bindings
  78if the device tree is used.
  79
  80Additionally ina226 supports update_interval attribute as described in
  81Documentation/hwmon/sysfs-interface.rst. Internally the interval is the sum of
  82bus and shunt voltage conversion times multiplied by the averaging rate. We
  83don't touch the conversion times and only modify the number of averages. The
  84lower limit of the update_interval is 2 ms, the upper limit is 2253 ms.
  85The actual programmed interval may vary from the desired value.
  86
  87General sysfs entries
  88---------------------
  89
  90======================= ===============================
  91in0_input               Shunt voltage(mV) channel
  92in1_input               Bus voltage(mV) channel
  93curr1_input             Current(mA) measurement channel
  94power1_input            Power(uW) measurement channel
  95shunt_resistor          Shunt resistance(uOhm) channel
  96======================= ===============================
  97
  98Sysfs entries for ina226, ina230 and ina231 only
  99------------------------------------------------
 100
 101======================= ====================================================
 102in0_lcrit               Critical low shunt voltage
 103in0_crit                Critical high shunt voltage
 104in0_lcrit_alarm         Shunt voltage critical low alarm
 105in0_crit_alarm          Shunt voltage critical high alarm
 106in1_lcrit               Critical low bus voltage
 107in1_crit                Critical high bus voltage
 108in1_lcrit_alarm         Bus voltage critical low alarm
 109in1_crit_alarm          Bus voltage critical high alarm
 110power1_crit             Critical high power
 111power1_crit_alarm       Power critical high alarm
 112update_interval         data conversion time; affects number of samples used
 113                        to average results for shunt and bus voltages.
 114======================= ====================================================
 115
 116.. note::
 117
 118   - Configure `shunt_resistor` before configure `power1_crit`, because power
 119     value is calculated based on `shunt_resistor` set.
 120   - Because of the underlying register implementation, only one `*crit` setting
 121     and its `alarm` can be active. Writing to one `*crit` setting clears other
 122     `*crit` settings and alarms. Writing 0 to any `*crit` setting clears all
 123     `*crit` settings and alarms.
 124