This example is a simple ADC sample. For more information please see ADC <../../firmwareapi/pycom/machine/adc.md>__.

## Calibration¶

Currently the ESP32’s ADC is not calibrated from the factory. This means it must be calibrated each time you wish to use it. To do this you must firstly measure the internal voltage reference. The following code will connect the 1.1v reference to P22