About

This library provides an analogWrite function, tone and Servo support for ESP32

Licensed under the MIT license.

This is heavily based on library https://github.com/erropix/ESP32_AnalogWrite/tree/master

Usage

The library will do all the timer setup and channel selection work behind the scene so you don't have to worry about that.

Fade Example

#include <Arduino.h>
#include <analogWrite.h>

int step = 1;
int brightness = 0;

void setup() {
}

void loop() {
  brightness += brightStep;
  analogWrite(LED_BUILTIN, brightness);
  
  if ( brightness == 0 || brightness == 255 ) {  
     brightStep = -brightStep;     
  }
  
  delay(10);  
}

Default Value Range

Call the analogWrite function like in standard Arduino framework:

analogWrite(LED_BUILTIN, 255); // value range 0-255 so 255 = 100%

Timer Resolution

The default timer resolution is set to 13 bits in all the 16 channels, if you want to change that, use the analogWriteResolution function:

analogWriteResolution(10); // set resolution to 10 bits for all pins
analogWriteResolution(LED_BUILTIN, 10); // set resolution to 10 bits for LED pin

PWM Frequency

The default PWM frequency is set to 5000 Hz in all the 16 channels, if you want to change that, use the analogWriteFrequency function:

analogWriteFrequency(10000); // set frequency to 10 kHz for all pins
analogWriteFrequency(LED_BUILTIN, 10000); // set frequency to 10 kHz for LED pin

Please note that both timer resolution and PWM frequency should be calculated to get the expected results, if frequency is not set correctly, the output PWM signal won’t be as expected, read more about Supported Range of Frequency and Duty Resolution in the official Espressif documentation website.

Servo

Servo signal is directly set using the following function:

analogServo(2, 90); // Sends 90 degrees signal to pin 2 (0 degrees = 600ms 180 degrees = 2400ms at 50Hz)
analogServo(2, 500); // Sends 500ms signal to pin 2 (if second argument > 200 then is converted to ms at 50Hz)
analogServo(2, 4000); // If the second argument is greater or equal to 4000 detaches servo pin, in this case pin 2

Tone

Sends tone of a given frequency and duration to a pin:

tone(22, 500, 200); // Sends to pin 22 a 500Hz tone during 200ms
tone(23, 1000); // Sends to pin 23 a 1000Hz tone
notone(23); // kill tone in pin 23

Issues

Since this library uses the ESP32 timers, when using different frequencies among the channels, there may appear some incompatibilities. To avoid this, you must assign the same frequencies to each of the 4 timers of the ESP32. For example: channels 0,1,8,9 use timer 0; therefore, these channels must have the same frequency. Same happens for channels 2,3,10,11 which use timer 1. Since the assignation of channels is ordered sequentially, each function must be initiated in a way that they use same timer for same frequency.