# How to generate PWM output representing a sine wave on the ESP32 (Arduino/PlatformIO)

The following function will compute the value of a sine wave using `micros()` as a timebase, with adjustable frequency. It is hardcoded to expect a 12 bit resolution PWM

```/**
* @brief Calculate the PWM duty cycle (assuming 12 bits resolution) of a sine wave of
* given frequency. micros() is used as a timebase
*
* @param frequency The frequency in Hz
* @return int the corresponding 12-bit PWM value
*/
int sinePWMValue(float frequency) {
unsigned long currentMicros = micros(); // get the current time in microseconds

// calculate the sine wave value for the current time
int sineValue = 2048 + 2047 * sin(2 * PI * currentMicros / (1000000 / frequency));
return sineValue;
}```

Based on this, we can use the basic code of our previous post ESP32 minimal Arduino PWM output example (PlatformIO) to generate a 1Hz sine wave (represented by a 10kHz PWM):

```#include <Arduino.h>
#include <driver/ledc.h>

void setup() {
Serial.begin(115200);

ledcSetup(LEDC_CHANNEL_0, 10000 /* Hz */, 12);

ledcAttachPin(GPIO_NUM_14, LEDC_CHANNEL_0);
ledcWrite(LEDC_CHANNEL_0, 2048); // 50%
}

/**
* @brief Calculate the PWM duty cycle (assuming 12 bits resolution) of a sine wave of
* given frequency. micros() is used as a timebase
*
* @param frequency The frequency in Hz
* @return int the corresponding 12-bit PWM value
*/
int sinePWMValue(float frequency) {
unsigned long currentMicros = micros(); // get the current time in microseconds

// calculate the sine wave value for the current time
int sineValue = 2048 + 2047 * sin(2 * PI * currentMicros / (1000000 / frequency));
return sineValue;
}

void loop() {
// Example of how to change the duty cycle to 25%
ledcWrite(LEDC_CHANNEL_0, sinePWMValue(1.0));
}```