REPL is on the USB-OTG connector.

resources

features

ESP32-S3

USB CDC On Boot

The chip exposes a USB CDC (virtual COM) at boot via the ROM “USB Serial/JTAG” peripheral. You get serial console logs and can flash with

  • [] enable
  • [] disable

USB DFU On Boot

The firmware enumerates as USB DFU class at boot (TinyUSB). You can update the app with dfu-util. Not the ROM bootloader.

  • [] enable
  • [] disable

Short answer: “App” means your firmware application image (factory/OTA slot like ota_0/ota_1), not the ROM bootloader.

  • USB DFU on ESP32‑S3 is provided by your running app via TinyUSB.
  • dfu-util updates the application partition(s) that your app exposes (factory or OTA slots).
  • It does not use or update the ROM bootloader (immutable) and typically not the ESP‑IDF second‑stage bootloader in flash unless you explicitly implement that.
  • To flash bootloader/partition table, use esptool via UART0 or USB Serial/JTAG (ROM downloader).

USB Firmware MSC On Boot:

  • [] Disabled
  • [] Enabled (Requires USB-OTG Mode)

USB Mode

  • [] Hardware CDC and JTAG - Uses the ROM “USB Serial/JTAG” composite device. Provides CDC (console/flashing) and JTAG debugging over the same USB. Lightweight, but limited to CDC+JTAG only.
  • [] USB-OTG (TinyUSB) - Runs the full TinyUSB stack. Lets you expose CDC, MSC, MTP, HID, etc., or act as USB host. Incompatible with USB Serial/JTAG while active (no JTAG-over-USB).

Upload Mode

  • [] UARTO / Hardware CDC - Official ROM download channels for esptool (UART0 pins or USB Serial/JTAG). Reliable for flashing and logs.
  • [] USB-OTG CDC (TinyUSB) - App‑level CDC provided by TinyUSB. Good for REPL/console, but not for ROM flashing with esptool unless your app explicitly reboots to the ROM downloader.

error log

E (291) quad_psram: PSRAM ID read error: 0x00ffffff, PSRAM chip not found or not supported, or wrong PSRAM line mode
E (291) esp_psram: PSRAM enabled but initialization failed. Bailing out.
MicroPython v1.25.0 on 2025-04-15; Generic ESP32S3 module with ESP32S3

board

ref