ESP32 Forum

Hi,

I planned to use a ESP32-S3 (https://www.espressif.com/sites/default ... eet_en.pdf) for a project, where many IO-pins will be used. I flash the ESP32-S3 with the integrated JTAG over USB.

There are some pins, where I'm now unsure, if I can use them for the specific interface (Strapping Pins and RXD0/TXD0):

- GPIO0 -> Here i need to ensure, that at startup the correct logic is applied (1in my case)
- GPIO3 -> Need floating at startup, so I will not use this GPIO
- GPIO45/46 -> Need to ensure a logic 0 at startup

So, that should fit so far. But what is about RXD0 and TXD0? Can I use them as I2C with Pull-Ups or are there any restrictions?

Yes. Be aware that normally there will be some startup chatter on TxD0 - if you're using this pin for I2C and the other line stays idle, this is unlikely to cause an issue, though. (Also note that dependent on the module/board, TxD0 may have a built-in 500 ohm series resistor. It probably won't interfere too much with I2C, but if you're having issues running I2C at a high bitrate, it may be because the resistor limits the slew rate.)