I2C The ESP32 has two I2C channels and any pin can be set as SDA or SCL. When using the ESP32 with the Arduino IDE, the default I2C pins are: GPIO 21 (SDA) GPIO 22 (SCL) If you want to use other pins, when using the wire library, you just need to call: Wire. begin (SDA, SCL);

The pins with a blue rectangle in the figure below. However, you can set almost any pin as I2C via software. To learn more about I2C with the ESP32, read our guide: ESP32 I2C Communication: Set Pins, Multiple Bus Interfaces and Peripherals (Arduino IDE) For the ESP 12E, the pins often used for I2C are GPIO 5 (SCL) and GPIO 4 (SDA). Regards, Sara

Also, everyone says to use the default GPIO (21 and 22) for I2C but my ESP32-S3-DevKitC-1U V1.0 (external antenna) does not have a GPIO 22 broken out on the board, and I cannot find what the development board’s default I2C pins are. It has two I2C peripherals also.

btw, I2C address scanner sketch I used, but is finding only one BME. An adapted version, see link in my 1st blog, and addessing second TwoWire(1) is also only finding the first BME280, connected to the default i2c-pins. further: I’ve available both types BME280 (4 and 6 pins), but I used for my test two 4-pin BME280

I want to assign different i2c pins for use with a BH1750 light sensor. You have a very nice tutorial that does this very thing for the BME280 sensor, and when I implement your code, it works fine … but when I try to do it for the BH1750 sensor, it doesn’t.

These sensors use I2C or SPI to communicate, 2 or 4 pins are required to interface. Adafruit invests time and resources providing this open source code, please support Adafruit and open-source hardware by purchasing products from Adafruit! Written by Limor Fried & Kevin Townsend for Adafruit Industries.

On my ESP8266 board I would like to (or rather, I have to) map the I2C pins to other pins like e.g.GPIO3 and GPIO1. These pins are by default RXD0 and TXD0. I would like to use the wire.begin instruction. Is this possibe or does it interfer with other functions?

The GPIOs for the OLED display are not referenced in the code, because those are the default I2C pins of the ESP32. So, when you initialize the display, if you don’t reference any pins, it will use the default I2C pins. The Web Server example, defines the pins, because those boards don’t use the default I2C pins. I hope this helps. Regards ...

below is exact copy of the GitHub with i2c pins/channel changed. from machine import Pin, I2Ca from time import sleep import network from umqtt.simple import MQTTClient import config import BME280 # Constants for MQTT Topics MQTT_TOPIC_TEMPERATURE = ‘pico/temperature’ MQTT_TOPIC_PRESSURE = ‘pico/pressure’ MQTT_TOPIC_HUMIDITY = ‘pico ...

Then, change the SDA and SCL pins to GPIO21 and GPIO22, respectively. Also, make sure that you have uploaded the library first. With that library you don’t need to scan for an I2C device. It automatically detects the device. Are you having trouble uploading the library? Can you test the example first and see if it works? Let me know how you ...