adc 12 bit

[iddq]

Why is it converted to 10 bit if the next line assumes it is 12 bit wide.

ArduinoCore-sam/cores/arduino/wiring_analog.c

Line 115 in eed66e7

ulValue = adc12b_get_latest_value(ADC12B) >> 2;

[matthijskooijman]

At first glance, seems like a bug to me. I thought that maybe adc12b_get_latest_value would return a zero padded value, but it seems to just return the LCDR register as-is:

ArduinoCore-sam/system/libsam/source/adc12_sam3u.c

Lines 243 to 246 in c893c62

	uint32_t adc12b_get_latest_value(const Adc12b *p_adc)
	{
	return p_adc->ADC12B_LCDR;
	}

And that register contains the 12-bit ADC value in the lower 12 bits:

(Note that the upper 4 bits can contain the channel number, but only if enabled, so I suspect this is not the case here and these are always zero and can be ignored).

Do you happen to have a Due you could test if this is indeed broken? Should be easy, if all analogRead values for these pins are off by a factor four, then it is really a bug.

[iddq]

I can't test it. I don't have DUE with SAM3U4E