Can't flash ESP32-S2-Mini-2 module (boot loop?)

[icematter]

Hi guys, I need help!!

I've flashed many ESP8266 and ESP32-WROOM modules by the past with no issues but it's my first time using ESP32-S2 module (I needed native USB support).

I'm trying to flash a esphome firmware onto an ESP32-S2-Mini-2 module. I connected VCC, GND, RX, TX pins properly and I did the proper GPIO0 to GND & EN(RST) to GND sequence but I haven't been able to flash with any tool.

I get the following error:

Unexpected error: ESP Chip Auto-Detection failed: Failed to connect to Espressif device: Invalid head of packet (0x45): Possible serial noise or corruption.



It feels like the tool is trying to identify the chip but it can't communicate with it properly because the chip is actively sending content; here what I see when I check at the logs (it goes on forever):



It looks like the module is boot looping for some reason... Lines seems to be truncated as if there was unstable VCC power supplied to it making restart in loop. I checked the voltage sent to the chip by the FDTI adapter it is a stable 3.1v.

I also trying plugging the VCC, GND, GPIO19 (USB D-) & GPIO20 (USB D+) to an USB connector (skipping the use of a FDTI adapter) in hopes that would be another way to flash but the PC did not recognize the module as a COM port when connected.

Here is my connections on the module (sorry for the flux):



Notes:
- I tried flashing the chip using a FT232 FTDI USB to TTL adapter (@ 3.1v)
- I also tried powering the chip during the flash with an adjustable power supply (3.3v & 3.5v @ 1.0 amp) and a 3.3v supply stepped down directly from a USB port's 5v.
- I tried to flash a second ESP32-S2 (same result)
- I tried multiple usb cables and rechecked my wiring multiple times
- To flash (in order):
- I shorted the GPIO0 pin to GND and the EN pin to GND
- Waited a few seconds, then I stopped shorting the EN pin to GND
- Then a waited a few seconds and I stopped shorting the GPIO0 pin to GND
- Using software (Arduino IDE, Esptool (Executable or WebSerial/Adafruit on Chrome)), I selected the proper COM port and started the flashing process.

What can I do to make the flashing work?

Any help would be greatly appreciated!

[lbernstone]

You need a RC timer on the EN line, 10KΩ/1uF. See the reference schematic

[ESP_Sprite]

Also that terminal screenshot looks like the ESP is getting too little power... perhaps your power supply lines are too thin/long? Adding a large cap (100u electrolytic or something, whatever you have in your parts bin) to the 3.3v power supply close to the pads of the module might help then.