My Heltec LoRa32 V3.1 does not work with my BME280 sensor

#1

Hello,

I would like to operate a BME280 sensor on a Heltec LoRa32 V3.1. Unfortunately, I don’t know which pins I can use on the Heltec controller. I don’t want to use pins 17 and 18, which are only soldered on the back.

Thank you very much for your help.

#2

I suggest these 9 pins GPIO(19, 20, 21, 26, 33, 34, 45, 47, 48).

#3

Note that the WiFi LoRa 32 V3 modules use the first I2C bus to drive the onboard OLED display and, as a consequence, you will need to define and use a second I2C bus (TwoWire(1) or Wire1) for any other I2C device, like your BME280 sensor.

#4

The only way that should work is via the rear pins 17 and 18. These are not brought out, so you have to solder. But I don’t dare to do that.

So I thought there must be alternative pins.

Unfortunately, I don’t know much about the second I2C bus yet.

#5

Would suggest you read and digest this article which uses the BME sensor in the examples, https://randomnerdtutorials.com/esp32-i2c-communication-arduino-ide/. The pins that you can define for your specific needs are shown on the Heltec pinout diagram which is available on the heltec product page and have been listed above

#6

With this code (from user machepro) it now works for me:

TwoWire Wire2(1);

In the setup:

Wire2.begin(41,42); /* (GPIO SDA and SCL) */
status = bme.begin(0x76, &Wire2);

Thank you for your help.