PWM onf ESP32-S3 GPIOs

Development Boards ESP32
1

In my attempt to debug the I2S output of the Thing Plus - ESP32-S3, I had two questions:

  1. What GPIOs can I use if GPIOs 33, 34, 38, and 39 are already used for the SD card SPI?
  2. Does PWM work on all GPIOs I try to use for I2S?

To answer the first question, I selected the following GPIOs based on the board schematics, ensuring they are not involved in other communication: GPIOs 1, 2, 4, 5, 6, and 7.

GPIOs

Next, I tried to generate pulses on these GPIOs using the following simplified code:

// PWM Configuration
#define PWM_FREQUENCY 5000  // 5 kHz
#define PWM_PERIOD (1000000 / PWM_FREQUENCY) // Period in microseconds
  const int pwmPins[] = {1, 2, 4, 5, 6, 7};
  const int numPins = 6;
 
  void setup() { 
     for (int i = 0; i < numPins; i++) {
         pinMode(pwmPins[i], OUTPUT);
     }
  }
 
  void generatePWM(int pin) {
      digitalWrite(pin, HIGH);
      delayMicroseconds(PWM_PERIOD / 2); // 50% duty cycle
      digitalWrite(pin, LOW);
      delayMicroseconds(PWM_PERIOD / 2);
  }
 
 void loop() {
     generatePWM(1);
  ..........
 }

After checking the pins with an oscilloscope, I found that only GPIOs 1 and 2 were producing PWM.

Here are the test results for the selected GPIOs:

GPIO number Board connector number Prodused PWM
1 5 V
2 6 V
4 8 X
5 9 X
6 10 X
7 11 X

What am I missing in my understanding?

2

Well, the solution was simple—I had the schematics wrong. The numbers I thought referred to ‘Board connectors’ were actually ESP32 pin numbers. The correct term is PTH (Plated Through Hole). PTH numbers are the same as GPIO numbers—it’s as simple as that. :slight_smile:

The issue is solved, I2S is working, sound is playing :musical_notes:

3

Good to know that it is working. Thanks for the update.