Chapter 4. Software framework
When using the ESP32-WROVER-B module with release/v4.2 version of ESP-IDF, I set the GPIO as an
ADC interface, and then set GPIO to other IO mode while with IO mode not eective without any hardware
reset, this GPIO does not respond. How do I release the corresponding GPIO mode?
• Please do not set the ADC interface as input-only GPIO.
• When disabling the ADC interface mode, please use adc_digi_stop() to disable the ADC.
What is the measurement error between the ADCs of the ESP32 chip?
By default, the measurement error between ESP32 ADCs is ±6%, please refer to ESP32 datasheet for
details.
Can ESP32 measure dierent data from two ADC channels at the same time, such as current and voltage?
It is not possible to read multiple ADC channels at the same time using one ADC, but you can poll the
data of both ADC channels in turn.
When ESP32-S3 ADC is congured as ADC_ATTEN_DB_11, why does the measured voltage not reach 3100
mV?
When ESP32-S3 ADC1 or ADC2 is congured as ADC_ATTEN_DB_11, the voltage measurement
should be in the range of 0 ~ 3100 mV. However, the maximum voltage measurement of some chips
may be less than 3100 mV due to consistency issues. You may use the following two solutions to x
this issue:
• Solution 1: Try to avoid using the boundary voltage values. You can use a divider circuit to reduce the input
voltage to an intermediate value for higher accuracy and consistency.
• Solution 2: Use the software ADC Range Extension Solution to increase the maximum voltage measurement
to 3300 mV.
Can we use GPIO0 as the ADC pin when using ESP32 as a Wi-Fi access point?
• The ESP32 ADC2 pins cannot be used when you are using Wi-Fi. So, if you are having trouble getting the
value from an ADC2 GPIO while using Wi-Fi, you may consider using an ADC1 GPIO instead. For more
details, please refer to Hardware Limitations of ADC Continuous Mode and Hardware Limitations of ADC
Oneshot Mode.
• The GPIO0, GPIO2, GPIO5, GPIO12 (MTDI), and GPIO15 (MTDO) are strapping pins. When using GPIO0
for other functions, you need to pay attention to the GPIO level during power-up. If the GPIO0 level is low
during power-up, the chip can enter the download mode. For more infomation, please refer to ESP32 datasheet.
I tried to test the functionality of ADC2 using GPIO19 and GPIO20 of ESP32-S3 based on “esp-
idf/examples/peripherals/adc/oneshot_read”example and set the attenuation parameter of ADC2 to 11 dB.
When the input voltage is 0.6 V, why are the test results 1.1 V and 2.8 V?
• Please check whether both two ADC2 channels have been congured according to
adc_oneshot_cong_channel().
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