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drivers: adc: sam0: Adjust resolution with the oversampling factor #75201

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drivers: adc: sam0: Adjust resolution with the oversampling factor #75201

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40 changes: 33 additions & 7 deletions drivers/adc/adc_sam0.c
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@decsny decsny Aug 22, 2024 •
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please make the commit title clear that this is specific to sam, ie it should start with drivers: adc_sam0:

Original file line number Diff line number Diff line change
Expand Up @@ -343,26 +343,52 @@ static int start_read(const struct device *dev,
switch (sequence->resolution) {
case 8:
if (sequence->oversampling) {
LOG_ERR("Oversampling requires 12 bit resolution");
LOG_ERR("Oversampling requires minimum 13 bit resolution");
return -EINVAL;
}

ADC_RESSEL(adc) = ADC_RESSEL_8BIT;
break;
case 10:
if (sequence->oversampling) {
LOG_ERR("Oversampling requires 12 bit resolution");
LOG_ERR("Oversampling requires minimum 13 bit resolution");
return -EINVAL;
}

ADC_RESSEL(adc) = ADC_RESSEL_10BIT;
break;
case 12:
if (sequence->oversampling) {
ADC_RESSEL(adc) = ADC_RESSEL_16BIT;
} else {
ADC_RESSEL(adc) = ADC_RESSEL_12BIT;
LOG_ERR("Oversampling requires minimum 13 bit resolution");
return -EINVAL;
}
ADC_RESSEL(adc) = ADC_RESSEL_12BIT;
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@nandojve nandojve Dec 22, 2024

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The ADC resolution is 12bit max.
image

However, if you want to Accumulate, Average or Oversampling, see
image

Check below sections:
45.6.2.9 Accumulation
45.6.2.10 Averaging
45.6.2.11 Oversampling and Decimation

This change must work for all sam0 series.

This possible it related to #76963

break;
case 13:
if (sequence->oversampling != 2U) {
LOG_ERR("13 bit resolution requires an oversampling of 2");
return -EINVAL;
}
ADC_RESSEL(adc) = ADC_RESSEL_16BIT;
break;
case 14:
if (sequence->oversampling != 4U) {
LOG_ERR("14 bit resolution requires an oversampling of 4");
return -EINVAL;
}
ADC_RESSEL(adc) = ADC_RESSEL_16BIT;
break;
case 15:
if (sequence->oversampling != 6U) {
LOG_ERR("15 bit resolution requires an oversampling of 6");
return -EINVAL;
}
ADC_RESSEL(adc) = ADC_RESSEL_16BIT;
break;
case 16:
if (sequence->oversampling != 8U) {
LOG_ERR("16 bit resolution requires an oversampling of 8");
return -EINVAL;
}
ADC_RESSEL(adc) = ADC_RESSEL_16BIT;
break;
default:
LOG_ERR("ADC resolution value %d is not valid",
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