Can I use GPIO 12 and 13 for I2C bus?

pmi2410
Posts: 13
Joined: Sun Nov 10, 2024 6:37 pm

Can I use GPIO 12 and 13 for I2C bus?

Postby pmi2410 » Wed Nov 19, 2025 5:58 pm

I am a bit confused by the documentation for the ESP32S3 N8R16 devkit boards. These boards have 2 USB-C connectors on the side away from the processor and the reset/boot buttons up near the processor. I think they are devkitc-1.1 boards. I am attaching them to a 4 layer PCB, so it would be very hard to re-route the signals if I am using the wrong GPIOs.

My questions are:
1. Can I use GPIO 12 and 13 for an I2C bus? Some references say GPIO 12 is a boot strapping pin, others say OK.
2. What are the internal pullups for these two pins? I want to make sure I have the right level of pullups on these two lines. Some references say GPIO 13 is only for SDI bus, and has no pullup, others say OK.

ves011
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Re: Can I use GPIO 12 and 13 for I2C bus?

Postby ves011 » Wed Nov 19, 2025 7:27 pm

1. There are no constraints for GPIO12, GPIO13 so its safe to use them for i2c
Strapping pins for S3 are, according to the datasheet, GPIO 0, 3 45 and 46
2. Internal pull-up/down, according to the same data sheet is 45k, so too high for I2C

pmi2410
Posts: 13
Joined: Sun Nov 10, 2024 6:37 pm

Re: Can I use GPIO 12 and 13 for I2C bus?

Postby pmi2410 » Wed Nov 19, 2025 10:17 pm

Thanks!

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