| Nest Magwheel |
| ============= |
| |
| The magwheel driver outputs the changing position of the Nest dial/wheel by |
| reading the direction of the magnetic field from a magnetic strip |
| with repeating North/South poles. |
| |
| Required Properties: |
| ------------------- |
| - compatible: "nestlabs,vf610-adc-magwheel"; |
| - vref-supply: The regulator supply ADC refrence voltage. |
| - reg: Offset and length of the register set for the device |
| - interrupts: Should contain the interrupt for the device |
| - nestlabs,adc-channels-used: List of two channels used from an ADC that are |
| connected to the two outputs of the hall effect sensor. |
| - nestlabs,adc-channel-midpoints = (See Below) |
| |
| adc-channels-midpoints must be physically tested to find the middle ADC value |
| for the two channels (halfway between the max and min). |
| I believe that if the magnetic strip is the same and the sensor |
| is the same, then these two values will be the same enough to be ok. |
| A small bit off will be ok. What will happen is that the North to South |
| part of the strip might move more/less then the South to North part. |
| But if this difference is small it won't be noticeable. |
| The reason that the two midpoints aren't the same is because the two sensors |
| are at different distances from the magnetic strip. |
| |
| |
| Example: |
| |
| magwheel: adc@02280000 { |
| compatible = "nestlabs,vf610-adc-magwheel"; |
| vref-supply = <&vgen6_reg>; |
| reg = <0x02280000 0x4000>; |
| interrupts = <GIC_SPI 100 IRQ_TYPE_LEVEL_HIGH>; |
| nestlabs,adc-channels-used = <1 2>; |
| nestlabs,adc-channel-midpoints = <1965 2038>; |
| status = "okay"; |
| }; |
