OTA without a USB or FTDI interface

[frankcohen]

Hi ESP32 people,

I am developing a new ESP32 board for a wrist watch. The board will be 55 mm round. Space is limited. I used SP32-S3-WROOM-1 modules so far. The module comes with the ESP-IDF bootloader preinstalled. I'd like to remove the USB chip and cable connector from my board design and only use OTA for uploading and running programs. If my board has no USB how do I get the first program onto the ESP32 using OTA? Does the bootloader on a fresh new module know to wait for an OTA upload of a new program?

-Frank

[ESP_Sprite]

It does not. Do note that the S3 has an USB interface internal to the chip you can use to upload the first program through, though. Just lead them out to a connector or two testpads and on the first bootup, use that to program the flash.

[Miraculix]

I've been playing around with the ESP32-S3-WROOM-1 in the past few days. You can use GPIO 19 and 20 as USB pins for flashing via USB connection, without any additional hardware needed (though you may want to add a ferrite bead for noise reduction and some 22pF capacitors on D+ and D-, because I don't know why ). Or you can use the TX and RX pins with a external board (e.g. with FTDI chip on a 3$ USB-UART programmer). Both types of connections will be accessible as COM port in ESP-IDF.

This is the board I use, if you're interested in the USB circuit (scroll down for schematic):
https://oshwlab.com/Miraculix200/esp32-s3-mini_copy