On Wed, May 15, 2019 at 01:58:08AM +0300, Serge Semin wrote:
> Add dt-binding documentation for the Texas Instruments ads1000/ads1100 ADCs
> driver.
>
> Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx>
> ---
> .../devicetree/bindings/hwmon/ads1000.txt | 61 ++++++++++++++++
Bindings should be separate patch.
> Documentation/hwmon/ads1000.rst | 72 +++++++++++++++++++
> 2 files changed, 133 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/hwmon/ads1000.txt
> create mode 100644 Documentation/hwmon/ads1000.rst
>
> diff --git a/Documentation/devicetree/bindings/hwmon/ads1000.txt b/Documentation/devicetree/bindings/hwmon/ads1000.txt
> new file mode 100644
> index 000000000000..3907b7da9b33
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/hwmon/ads1000.txt
> @@ -0,0 +1,61 @@
> +ADS1000/ADS1100 (I2C)
> +
> +This device is a 12-16 bit A-D converter with 1 input.
ADC's should be in bindings/iio/adc/
> +
> +The inputs can be used either as a differential pair of Vin+ Vin- or as a single
> +ended sensor for Vin+ GND. The inputs mode is platform-dependent and isn't
> +configured by software in any case.
> +
> +Device A-D converter sensitivity can be configured using two parameters:
> + - pga is the programmable gain amplifier
> + 0: x1 (default)
> + 1: x2
> + 2: x4
> + 3: x8
> + - data_rate in samples per second also affecting the output code accuracy
> + 0: 128SPS - +/- Vdd*0.488mV (default, ads1000 accepts this rate only)
> + 1: 32SPS - +/- Vdd*0.122mV
> + 2: 16SPS - +/- Vdd*0.061mV
> + 3: 8SPS - +/- Vdd*0.030mV
> + Since this parameter also affects the output accuracy, be aware the greater
> + SPS the worse accuracy.
> +
> +As a result the output value is calculated by the next formulae:
> +dVin = Cod * Vdd / (PGA * max(|Cod|)), where
> +max(|Cod|) - maximum possible value of the output code, which depends on the SPS
> +setting from the table above.
> +
> +The ADS1000/ADS1100 dts-node:
> +
> + Required properties:
> + - compatible : must be "ti,ads1000" or "ti,ads1100"
> + - reg : I2C bus address of the device
> + - #address-cells : must be <1>
> + - #size-cells : must be <0>
> + - vdd-supply : regulator for reference supply voltage (usually fixed)
> +
> + Optional properties:
> + - ti,gain : the programmable gain amplifier setting
> + - ti,datarate : the converter data rate
IIRC, we have standard properties for these.
> + - ti,voltage-divider : <R1 R2> Ohms inbound voltage dividers,
> + so dVin = (R1 + R2)/R2 * dVin
> +
> +Example:
> +
> +vdd_5v0: fixedregulator@0 {
> + compatible = "regulator-fixed";
> + regulator-name = "vdd-ref";
> + regulator-min-microvolt = <5000000>;
> + regulator-max-microvolt = <5000000>;
> + regulator-always-on;
> +};
> +
> +tiadc: ads1000@48 {
adc@48
> + compatible = "ti,ads1000";
> + reg = <0x48>;
> +
> + vdd-supply = <&vdd_5v0>;
> + ti,gain = <0>;
> + ti,voltage-divider = <31600 3600>;
> +};
> +
