Hello,
In an ESP32 gateway board I try to connect an ADC converter MCP3426. SDA to GPIO4 and SCK to GPIO12. Both pins are free to use according to the pinout information.
I also connected both pins to a 4k7 resistor to 3V3 according to I2C bus definition.
When I have this connected, I try to program the ESP32 using the USB and I receive the error "A fatal error occurred: Timed out waiting for packet content
Failed uploading: uploading error: exit status 2"
If i turn it off and on, the ESP32 gives a continuous error "12:36:59.007 -> invalid header: 0xffffffff"
I don't understand why this problem happens. Any idea? Thanks
Found the problem. Actually it's not related to I2C but to the pin I use, GPIO 12 must be LOW during boot and given that I2C pins are connected to +3V3 through the resistor, it wwas not LOW during the boot.
https://randomnerdtutorials.com/esp32-pinout-reference-gpios/
Thanks for update. I was going to say to look in the bootstrap table, it is also visible in ESP32-GATEWAY schematic, bottom-right.