acassis commented on PR #12621:
URL: https://github.com/apache/nuttx/pull/12621#issuecomment-2209609206
> @acassis Got it, I've added the peripheral support table to the BL808 page
(moved and expanded from the ox64 page) and created the new config. I'll go
ahead and mark this as ready for review, but I would still like to double check
about the ADC conversion return format:
>
> > Currently, the driver returns unsigned ADC readings on the least
significant 16 bits of the return data (ie max positive reading of 65535),
which is the output format for the ADC hardware as configured. From looking at
other ADC drivers, I saw that some also keep the same output format as provided
by the hardware, while others return their values shifted left to represent
signed 32-bit numbers. Is one of these approaches considered standard or
preferred over the other?
>
> If there is an expected output format for the return values, please let me
know so I can make sure the driver follows it.
The interface expect a data in "int32_t", but I think it is this way only
for compatibility for some ADC that could have different range (imagine an ADC
symmetric power supply voltage where you can have positive and negative
voltage).
```
CODE int (*au_receive)(FAR struct adc_dev_s *dev, uint8_t ch,
int32_t data);
```
For common ADC used on most microcontrollers the value will be only integer
0 to 65535 range for 16-bit, so you don't need to do anything else.
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