124 lines
3.9 KiB
ReStructuredText
124 lines
3.9 KiB
ReStructuredText
Kernel driver ina2xx
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====================
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Supported chips:
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* Texas Instruments INA219
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Prefix: 'ina219'
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Addresses: I2C 0x40 - 0x4f
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Datasheet: Publicly available at the Texas Instruments website
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https://www.ti.com/
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* Texas Instruments INA220
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Prefix: 'ina220'
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Addresses: I2C 0x40 - 0x4f
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Datasheet: Publicly available at the Texas Instruments website
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https://www.ti.com/
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* Texas Instruments INA226
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Prefix: 'ina226'
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Addresses: I2C 0x40 - 0x4f
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Datasheet: Publicly available at the Texas Instruments website
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https://www.ti.com/
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* Texas Instruments INA230
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Prefix: 'ina230'
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Addresses: I2C 0x40 - 0x4f
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Datasheet: Publicly available at the Texas Instruments website
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https://www.ti.com/
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* Texas Instruments INA231
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Prefix: 'ina231'
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Addresses: I2C 0x40 - 0x4f
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Datasheet: Publicly available at the Texas Instruments website
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https://www.ti.com/
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Author: Lothar Felten <lothar.felten@gmail.com>
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Description
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-----------
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The INA219 is a high-side current shunt and power monitor with an I2C
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interface. The INA219 monitors both shunt drop and supply voltage, with
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programmable conversion times and filtering.
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The INA220 is a high or low side current shunt and power monitor with an I2C
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interface. The INA220 monitors both shunt drop and supply voltage.
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The INA226 is a current shunt and power monitor with an I2C interface.
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The INA226 monitors both a shunt voltage drop and bus supply voltage.
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INA230 and INA231 are high or low side current shunt and power monitors
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with an I2C interface. The chips monitor both a shunt voltage drop and
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bus supply voltage.
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The shunt value in micro-ohms can be set via platform data or device tree at
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compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
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refer to the Documentation/devicetree/bindings/hwmon/ina2xx.txt for bindings
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if the device tree is used.
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Additionally ina226 supports update_interval attribute as described in
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Documentation/hwmon/sysfs-interface.rst. Internally the interval is the sum of
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bus and shunt voltage conversion times multiplied by the averaging rate. We
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don't touch the conversion times and only modify the number of averages. The
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lower limit of the update_interval is 2 ms, the upper limit is 2253 ms.
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The actual programmed interval may vary from the desired value.
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General sysfs entries
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---------------------
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======================= ===============================
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in0_input Shunt voltage(mV) channel
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in1_input Bus voltage(mV) channel
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curr1_input Current(mA) measurement channel
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power1_input Power(uW) measurement channel
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shunt_resistor Shunt resistance(uOhm) channel
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======================= ===============================
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Sysfs entries for ina226, ina230 and ina231 only
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------------------------------------------------
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======================= ====================================================
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in0_lcrit Critical low shunt voltage
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in0_crit Critical high shunt voltage
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in0_lcrit_alarm Shunt voltage critical low alarm
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in0_crit_alarm Shunt voltage critical high alarm
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in1_lcrit Critical low bus voltage
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in1_crit Critical high bus voltage
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in1_lcrit_alarm Bus voltage critical low alarm
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in1_crit_alarm Bus voltage critical high alarm
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power1_crit Critical high power
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power1_crit_alarm Power critical high alarm
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update_interval data conversion time; affects number of samples used
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to average results for shunt and bus voltages.
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======================= ====================================================
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.. note::
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- Configure `shunt_resistor` before configure `power1_crit`, because power
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value is calculated based on `shunt_resistor` set.
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- Because of the underlying register implementation, only one `*crit` setting
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and its `alarm` can be active. Writing to one `*crit` setting clears other
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`*crit` settings and alarms. Writing 0 to any `*crit` setting clears all
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`*crit` settings and alarms.
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