ESP32 Forum

This is a code excerpt from my Arduino based project for an ESP32-WROOM-32U. I think I have address all my GPIO issues on the current revision of my board, and would like someone to verify my pinout is ok before I order new boards.
does anyone see any issues or have any questions?

TEMPC_BUS 12 //DS18B20 Bus

This might be problematic since the default state of a onewire bus is high. GPIO12 is a strapping pin which determines flash voltage, with high meaning 1.8V; while the module you are using has 3.3V flash.

You can overcome this by either using a different pin, or burning VDDSDIO Efuse to 3.3V. The latter is explained in https://github.com/espressif/esptool/wi ... e-vdd_sdio.

for the sake of testing, a onewire device connected to GPIO12 will NOT allow it to be programmed.

I can do 1 of 2 things.

1. move it to GPIO5 and get rid of my "on" led
2. do the fuse thing.

How do I determine if burning to 3.3v is the right thing to do? what considerations should I take?

thank you for putting that out there!

You can switch around the LED and the onewire pin if you want to. Just make sure to connect your LED from +3.3V through a resistor to GPIO12. That way, the pin is default-high (but note that you need to make the GPIO *low* in order to light the LED.)
*EDIT* Oops, that's wrong, it needs to be low. See Igrrs post under this.

Efuse solution will work, but if you plan to produce a lot of devices that would be an extra step to account for during production (although an easily scriptable one).

Swapping the LED as suggested by ESP_Sprite will also work if you wire the LED between GPIO12 and GND (you need GPIO12 to be low at reset for 3.3V strapping, not high).

Like this?

and after the esp boots, I dont need to manually pull it high, or do anything else to it?

Yes, like that, but flip the LED polarity, and you also need a resistor in series with the LED (usually around 1kOhm) — this applies to any other LEDs you have. If you want the LED to turn on you can set the pin as output and set level to high.

yes, the resistor was what I was wondering. Thank you, Ill go this route.