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By lim
#196047
I have SparkFun combo CSS811 BME280 board. Recently I experience, flash always fail. I have D2 line connected to SCL of Combo board. As soon as I pulled out the SCL line to D2, it works.I connect it to D23, D1. They work too. I have not tried on other pins, I am running the Kolban's hello program which has not run yet. As the issue is flashing.

Has anyone experienced similar thing?
By Valen
#196142
Pin D2 is an arduino designation, it's not on the ESPWroom32. By D2 I assume you mean pin GPIO02!?

https://github.com/espressif/esptool/wi ... -Selection

Assuming the above is correct:
As the SCL line must be pulled up to work for I2C, but pulled down or floating to enter serial bootloader mode (flash) that is never going to work. Either disable any external pull-up resistor on that pin and use internal pull-up functionality of the chip, or supply the resistor it with power through another pin that you can set high in Setup (before wire.begin or whenever your program uses I2C).