🛠 Clavier USB HID via l'USB-OTG natif (TinyUSB)

Objectives

Transform the ESP32-S3 into a USB HID peripheral (keyboard) thanks to its native USB-OTG controller on GPIO19 (D-) and GPIO20 (D+), via the TinyUSB stack integrated into the Arduino core. This is one of the major differences from the classic ESP32: no additional chip is required. You will also discover the major constraint of the S3's dual USB: the "TinyUSB (OTG)" mode and the "Hardware CDC and JTAG" mode compete for the same pins; you cannot do everything at the same time without a second physical connector.

Hardware

• 1 ESP32-S3 board with USB on GPIO19/20 (DevKitC-1 v1.1, Feather S3, XIAO in OTG mode)
• 1 push button between GPIO1 and GND
• 1 second USB port (or a second computer/tester) to reflash if the HID takes over
• Arduino IDE with a recent esp32 core

Complete code

// Clavier HID sur USB-OTG natif (GPIO19/20) via TinyUSB
// Outils Arduino : USB Mode = "TinyUSB Device" (ou "OTG"), USB CDC = Disabled
#include "Arduino.h"
#include "USB.h"
#include "USBHIDKeyboard.h"

USBHIDKeyboard Keyboard;
const uint8_t BTN = 1;
uint8_t etatPrecedent = HIGH;
unsigned long dernierBord = 0;

void setup {
  pinMode(BTN, INPUT_PULLUP);
  Keyboard.begin;
  if (!USB.begin) {
    // pas de hot-plug possible ici : le host verra le HID au prochain branchement
  }
}

void loop {
  uint8_t etat = digitalRead(BTN);
  if (etat == LOW && etatPrecedent == HIGH && millis - dernierBord > 120) {
    dernierBord = millis;
    Keyboard.begin;                 // s'assure que le HID est pret
    Keyboard.print("ESP32-S3 dit bonjour ");
    Keyboard.write(KEY_RETURN);
    Keyboard.end;
  }
  etatPrecedent = etat;
  delay(10);
}

Expected verification

After uploading and reconnecting the cable, the computer detects a new "USB Keyboard" (hidusb) device without a driver. Pressing the button enters the line "ESP32-S3 says hello" followed by Enter into any active text field. The USB enumeration goes through GPIO19/20, the only pins connected to the S3's OTG controller.

Common errors

• Forgetting to switch the "USB Mode" menu to TinyUSB: with Hardware CDC+JTAG mode, USB.begin fails silently because GPIO19/20 are not routed to the OTG.
• Losing the flash port: in TinyUSB mode, the enumeration serial port disappears if the program crashes before USB.begin; plan for a BOOT/RESET button to enter ROM download mode, or keep a second cable on UART0 (GPIO43/44).
• Expecting a reconnection: many hosts do not re-enumerate hot; after a flash, unplugging/replugging the cable is often necessary.
• Keyboard layout: Keyboard.write assumes a US layout; for a French AZERTY layout, use modifiers or the KeyboardFR class depending on the core versions.
• Confusing the two USBs: the "COM" port of the console (Serial/JTAG) and the HID OTG can coexist only if the board physically wires the two controllers to two distinct connectors.