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- ADC device binding
- There are no mandatory properties for ADC. However, if Voltage info is required,
- then there are two options:
- - use microvolts constraint or
- - use regulator phandle to enable/read supply's Voltage
- Properties and constraints:
- *optional and always checked, Voltage polarity info:
- - vdd-polarity-negative: positive reference Voltage has a negative polarity
- - vss-polarity-negative: negative reference Voltage has a negative polarity
- Chose one option, for each supply (Vdd/Vss):
- *optional and always checked, supply Voltage constants:
- - vdd-supply: phandle to Vdd regulator's node
- - vss-supply: phandle to Vss regulator's node
- *optional and checked only if the above corresponding, doesn't exist:
- - vdd-microvolts: positive reference Voltage value [uV]
- - vss-microvolts: negative reference Voltage value [uV]
- Example with constant 'Vdd' value:
- adc@1000000 {
- compatible = "some-adc";
- reg = <0xaabb000 0x100>;
- status = "enabled";
- vdd-microvolts = <1800000>;
- };
- Example of supply phandle usage, for the ADC's VDD/VSS references as below:
- _______ _______
- |Sandbox| |Sandbox|
- : PMIC : : ADC :
- . . . .
- | | (Vdd) | AIN0|-->
- | BUCK2|-------|VDDref |
- | (3.3V)| _|VSSref |
- |_______| | |_______|
- _|_
- For the above PMIC, the node can be defined as follows:
- sandbox_pmic {
- compatible = "sandbox,pmic";
- ...
- buck2: buck2 {
- regulator-name = "SUPPLY_3.3V";
- regulator-min-microvolt = <3300000>;
- regulator-max-microvolt = <3300000>;
- };
- ...
- };
- For the above ADC, the node can be defined as follows:
- adc@0 {
- compatible = "sandbox,adc";
- vdd-supply = <&buck2>;
- vss-microvolts = <0>;
- };
- The ADC uclass code, will enable the supply before start of the conversion,
- but it will not configure the regulator settings.
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