dr.quark asked 3 years ago
I’ve got LoRa running on the TTGO-OLED board with OneWire reading single DS18B20 sensors per pin. It works on GPIO 13 and 25, but not on 32 and 33. The pins (32/33) are bidirectional and don’t seem to have any listed cautions about using them for general digital I/O. Am I missing something?
Sara Santos Staff answered 3 years ago
Hi.
I’m not sure.
If you take a look at the board’s pinout, there is a small * next to those GPIOs.
I don’t know what that means. I couldn’t find a pinout that explained what the * means. But maybe it has something to do with that.
Regards,
Sara
dr.quark answered 3 years ago
It appears to me that pins 32 and 33 have a fundamental problem in the Arduino IDE core data tables for this chip. Even code like the following fails to put them into OUTPUT mode. I think you should color these two pins in your ESP32 pinout at least yellow (I have not tried to use them in INPUT mode, yet). The ESP32 hardware technical manual shows both of them as bi-directional, and then all pins of higher number as input only. So something is missing, somewhere.
“`
REG_SET_FIELD(GPIO_PIN_MUX_REG[32], MCU_SEL, GPIO_MODE_INPUT_OUTPUT);
REG_SET_FIELD(GPIO_PIN_MUX_REG[33], MCU_SEL, GPIO_MODE_INPUT_OUTPUT);
```Hi.
Thanks for pointing that out.
I need to investigate this subject further.
Regards,
Sara