adc.txt
1.82 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
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.