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• This example will show you how to use I2C module by running tasks on i2c bus:

  • read external i2c sensor, here we use a HTU21D humidity and temperature sensor.
  • write to an I2C port expander IC (MCP23017) to interfacing with relays
  • Use I2C port (master mode) in ESP32.

• Pin assignment:

  • I2C master :

    • GPIO22 is assigned as the SCL (clock) signal of i2c master port
    • GPIO21 is assigned as the SDA (data) signal of i2c master port

  • LED PWM Dimmer

    • GPIO16 is assigned as a PWM output using the ledc peripheral of the ESP32
    • GPIO17 is assigned as a PWM output using the ledc peripheral of the ESP32

• Test items:

  • Connect to Wifi.
  • Conned to MQTT Broker securely (using secure web sockets)
  • Subscribe to topics for the dimmer and the relays/switch connected to the port expander
  • Periodically read temperature and humidity data (as soon as connected to MQTT), and publish to MQTT
  • Set port expander data (MCP23017) if data from subscribed topic arrives
  • Set led pwm data if subscribed topic arrives.

TODO:* Connect an IR Transmitter to control HVAC (air conditioner) and Fan