Re: [PATCH v2 1/7] dt-bindings: iio: adc: Add TI ADS126x ADC family

[David Lechner]

On 6/30/26 12:14 PM, Kurt Borja wrote:
> On Mon Jun 29, 2026 at 11:43 AM -05, David Lechner wrote:
>> On 6/29/26 11:27 AM, Kurt Borja wrote:
>>> On Mon Jun 29, 2026 at 9:21 AM -05, David Lechner wrote:
>>>> On 6/28/26 2:12 PM, Kurt Borja wrote:
>>>>> On Sun Jun 28, 2026 at 10:45 AM -05, David Lechner wrote:
>>>>>> On 6/28/26 12:36 AM, Kurt Borja wrote:
>>>>>>> The ADS1262 and ADS1263 are 32-bit, 38.4-kSPS delta-sigma ADCs with an
>>>>>>> integrated PGA, internal reference, excitation and burn-out current
>>>>>>> sources for sensor biasing and diagnostics. The ADS1263 adds a second,
>>>>>>> 24-bit delta-sigma ADC (ADC2) for background measurements.
>>>>>>>
>>>>
>>>> ...
>>>>
>>>>>>> +
>>>>>>> +patternProperties:
>>>>>>> +  "^channel@[0-9]+$":
>>>>>>> +    $ref: /schemas/iio/adc/adc.yaml#
>>>>>>> +    unevaluatedProperties: false
>>>>>>> +
>>>>>>> +    properties:
>>>>>>> +      reg:
>>>>>>> +        maxItems: 1
>>>>>>> +
>>>>>>
>>>>>> If we want to allow single-ended/pseudo-differential inputs, then we should
>>>>>> also allow single-channel (positive pin) and common-mode-channel (negative
>>>>>> pin) properties.
>>>>>>
>>>>>> This will also require additional common-mode-<N>-supply properties to allow
>>>>>> for the negative pin connected to something other than GND.
>>>>>
>>>>> Ah interesting. Why the N though? wouldn't a single supply connected to
>>>>> AINCOM be enough here?
>>>>
>>>> In theory, any AINx could be a common mode input by connecting it to
>>>> a constant voltage supply.
>>>
>>> Technically yes, but there is a pin named AINCOM intended for this
>>> purpose. Can we do a simplification here? I propose having
>>>
>>>   common-mode-channel:
>>>     /* AINCOM pin */
>>>     const: 10
>>>
>>> That way we would only need one common-mode-supply. Would that be okay?
>>>
>>
>> Ideally, we shouldn't limit how the chip can be wired up in the devicetree
>> bindings. It doesn't mean that we have to implement everything in the driver
>> though.
> 
> Makes sense.
> 
> I just have a doubt: In the ADS112c14 bindings, is there a specific
> reason why you didn't describe common-mode-<N>-supply?
> 

For singled-ended inputs on ADS112c14, there is an internal
connection to GND, so it isn't possible to have a pseudo-
differential input like that. I guess technically, it could
still be possible, but wasn't a typical wiring described in
the datasheet like it is on ADS1263.