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docs: Correct ADC default resolution statement for ESP32-S2#11653

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me-no-dev merged 3 commits intoespressif:masterfromeMUQI:patch-1

Aug 5, 2025

Merged

docs: Correct ADC default resolution statement for ESP32-S2#11653

me-no-dev merged 3 commits intoespressif:masterfromeMUQI:patch-1

Aug 5, 2025

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eMUQI commentedJul 27, 2025

Description of Change

This PR corrects thedocumentation for analogReadResolution by removing an incorrect statement that the ESP32-S3 default ADC resolution is 13 bits.

As confirmed by the function's own documentation in the core header fileesp32-hal-adc.h, the default resolution for analogRead is 12 bits (producing a range of 0-4095).

Tests scenarios

Compiled and run on Seeed Studio XIAO ESP32S3 in version v3.3.0. By running the standard AnalogReadSerial example code, confirmed that the default output range is 0-4095, corresponding to 12-bit resolution.

arduino-esp32/cores/esp32/esp32-hal-adc.h

Lines 49 to 56 inc7520cc

	/*
	* Set the resolution of analogRead return values. Default is 12 bits (range from 0 to 4096).
	* If between 9 and 12, it will equal the set hardware resolution, else value will be shifted.
	* Range is 1 - 16
	*
	* Note: compatibility with Arduino SAM
	*/
	voidanalogReadResolution(uint8_tbits);

https://github.com/espressif/esp-idf/blob/346870a3044010f2018be0ef3b86ba650251c655/components/soc/esp32s3/include/soc/soc_caps.h#L129-L130

docs: Remove incorrect statement on ESP32-S3 default resolution

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eMUQI requested a review frompedrominatel as acode owner

July 27, 2025 12:13

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github-actionsbot commentedJul 27, 2025•
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lucasssvaz requested a review fromP-R-O-C-H-Y

July 27, 2025 16:07

P-R-O-C-H-Y requested changes

Jul 28, 2025

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Hi@eMUQI, I have checked the code and you are right about the S3. The documentation should say that for S2! Can you please instead of removing it change the S3 to S2? Thanks

P-R-O-C-H-Y added the Type: DocumentationIssue pertains to Documentation of Arduino ESP32 label

Jul 28, 2025

docs: Change ADC default resolution exception to ESP32-S2

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eMUQI changed the title~~docs: Remove incorrect statement on ESP32-S3 default resolution~~docs: Correct ADC default resolution statement for ESP32-S2

Jul 28, 2025

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eMUQI commentedJul 28, 2025

Hi@P-R-O-C-H-Y , thanks for the review and clarification!
I've updated the PR as you suggested. Could you please take another look?

P-R-O-C-H-Y approved these changes

Jul 28, 2025

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LGTM

P-R-O-C-H-Y added the Status: Pending MergePull Request is ready to be merged label

Jul 28, 2025

pedrominatel reviewed

Jul 28, 2025

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docs/en/api/adc.rst Outdated

		^^^^^^^^^^^^^^^^^^^^

		This function is used to set the resolution of ``analogRead`` return value. Default is 12 bits (range from 0 to 4095).
		This function is used to set the resolution of ``analogRead`` return value. Default is 12 bits (range from 0 to 4095)

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pedrominatelJul 28, 2025

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This is only for the chip revision v0.0. For v1.0, the resolution is 12 bits.

Please add a reference to theADC-112 Bit 1 of SAR ADC Does Not Flip errata.

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pedrominatelJul 29, 2025

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Hi@eMUQI, can you take a look?

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eMUQIJul 29, 2025

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Hi@pedrominatel,
Thanks for the clarification. Just to make sure I understand correctly:
The documentation should specify that the 13-bit default resolution only applies to ESP32-S2 chip revision v0.0, and I should also add a reference to theADC-112 Bit 1 of SAR ADC Does Not Flip errata.
Is that correct? If so, I will update the PR accordingly.
Thanks!