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authorPeter Rosin <peda@axentia.se>2018-04-23 23:08:06 +0200
committerJonathan Cameron <Jonathan.Cameron@huawei.com>2018-04-28 18:59:32 +0200
commit1351b50cc4b8abcab128febf3a27d01af44697b3 (patch)
tree3acb5a84be4e3285edad3ecf772668253d14f71a /Documentation
parentiio: accel: bcm150: Remove handling for regmap raw_read_max (diff)
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dt-bindings: iio: afe: add binding for current-sense-shunt
An ADC is often used to measure other quantities indirectly. This binding describe one cases, a current through a shunt resistor measured by the voltage over it. Signed-off-by: Peter Rosin <peda@axentia.se> Reviewed-by: Rob Herring <robh@kernel.org> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/iio/afe/current-sense-shunt.txt41
1 files changed, 41 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-shunt.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-shunt.txt
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+Current Sense Shunt
+===================
+
+When an io-channel measures the voltage over a current sense shunt,
+the interesting mesaurement is almost always the current through the
+shunt, not the voltage over it. This binding describes such a current
+sense circuit.
+
+Required properties:
+- compatible : "current-sense-shunt"
+- io-channels : Channel node of a voltage io-channel.
+- shunt-resistor-micro-ohms : The shunt resistance in microohms.
+
+Example:
+The system current is measured by measuring the voltage over a
+3.3 ohms shunt resistor.
+
+sysi {
+ compatible = "current-sense-shunt";
+ io-channels = <&tiadc 0>;
+
+ /* Divide the voltage by 3300000/1000000 (or 3.3) for the current. */
+ shunt-resistor-micro-ohms = <3300000>;
+};
+
+&i2c {
+ tiadc: adc@48 {
+ compatible = "ti,ads1015";
+ reg = <0x48>;
+ #io-channel-cells = <1>;
+
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ channel@0 { /* IN0,IN1 differential */
+ reg = <0>;
+ ti,gain = <1>;
+ ti,datarate = <4>;
+ };
+ };
+};