Noduino Analog IO

1 Analog Input

ESP8266 has a single ADC channel available to users. It may be used either to read voltage at ADC pin, or to read module supply voltage (VCC).

To read external voltage applied to ADC pin, use analogRead(A0). Input voltage range is 0 — 1.0V.

To read VCC voltage, ADC pin must be kept unconnected. Additionally, the following line has to be added to the sketch:

ADC_MODE(ADC_VCC); This line has to appear outside of any functions, for instance right after the #include lines of your sketch.

2 Analog Output

analogWrite(pin, value) enables software PWM on the given pin. PWM may be used on pins 0 to 16. Call analogWrite(pin, 0) to disable PWM on the pin. value may be in range from 0 to PWMRANGE, which is equal to 1023 by default. PWM range may be changed by calling analogWriteRange(new_range).

PWM frequency is 1kHz by default. Call analogWriteFreq(new_frequency) to change the frequency.