![]() resultadcEnd(pin): gets the result of the conversion (waits if ADC has not finished), returns 16-bit integer.adcBusy(pin): checks if conversion on the pin’s ADC bus is currently running (returns TRUE or FALSE).adcStart(pin): starts an ADC conversion on the attached pin’s bus. ![]() adcAttachPin(pin): Attaches a pin to ADC (also clears any other analog mode that could be on) and returns true if configuration is successful, else returns false.analogSetPinAttenuation(pin, attenuation): This function is the same as the previous one, except it sets the input attenuation for the specified pin.ADC_11db: sets an attenuation of 3.6 (Measurable input voltage range = 150 mV ~ 2450 mV).ADC_6db: sets an attenuation of 1.5 (Measurable input voltage range = 150 mV ~ 1750 mV).ADC_2_5db: sets an attenuation of 1.34 (Measurable input voltage range = 100 mV ~ 1250 mV).ADC_0db: sets no attenuation (Measurable input voltage range = 100 mV ~ 950 mV).analogSetAttenuation(attenuation): sets the input attenuation for all ADC pins.analogSetClockDiv(clockDiv): sets the divider for the ADC clock.It has an effect of increasing sensitivity. analogSetSamples(samples): sets the number of samples in the range.analogSetCycles(cycles): sets the number of cycles per sample.analogSetWidth(bits): sets the hardware sample bits and read resolution.analogReadResolution(bits): sets the sample bits and read resolution.analogReadMilliVolts(pin): get ADC value for a given pin/ADC channel in millivolts.There are other ADC functions that may be useful in other projects: This is done for you automatically each time you call analogRead(). In the graph below, the non-linearities at the lower and upper ends of the input voltage are clearly visible. You can find more information about this in a discussion on GitHub. The ADC converters on the ESP32 are non-linear in nature. Ideally, you would expect a linear behavior when using the ADC, but this is not the case. You cannot measure analog voltages between 0 and 5V directly. The ESP32’s ADC can only measure voltages ranging from 0 to 3.3V. Since there is a good chance of using WiFi on a microcontroller designed to use it, only the ADC1 can be used. ![]() The ADC2 pins cannot be used when Wi-Fi is enabled. There are several limitations that you should be aware of. Truth be told, ADC is not the ESP32’s strongest point. Moreover, the ADC resolution and channel range can be set programmatically. This results in a resolution of 3.3 volts / 4096 units, or 0.0008 volts (0.8 mV) per unit. In other words, it will convert input voltages ranging from 0 to 3.3V (operating voltage) into integer values ranging from 0 to 4095. The ADC in your ESP32 has a resolution of 12 bits, meaning that it can detect 4096 (2^12) discrete analog levels.
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