ESP32-S3 WROOM GPIO43 Open-Drain Drive Strength

[EricNRS]

I am using GPIO43 UART0 TX in open-drain configuration with a 1K pull-up resistor to 3.3V. When in this mode, the voltage is only pulled down to 1.16V instead of 0V. If I use GPIO44, the voltage is pulled down to 0V.

I could not find anything in the datasheet, TRM, or other documentation that mentions GPIO43 having limited pull-down capability.

Is there some documentation that I am missing?

Thanks,
Eric

[martaaay]

In the WROOM module, there's an in-series 500 ohm resistor on the U0TXD line. This might be causing your problem. Check out page 26: https://www.espressif.com/sites/default ... eet_en.pdf

[EricNRS]

R3, 499 ohm. Awesome, that's it! Thank you. I'll move the input to a different pin in a future hardware revision which also allows me to keep the UART0 debug interface for debug.

Thanks,
Eric