ESP32 multi-sensor IOT module

IOT sensor project to publish temperature and humidity readings to an MQTT topic.

Getting started

The MQTT_MAX_PACKET_SIZE value in the PubSubClient library will need to be updated from 128 to 256 to allow for adequately sized MQTT messages to be sent. Unfortunately the only way to do this is by editing the PubSubClient.h file directly.

Hardware

• ESP32 development board
• DHT11 temperature and humidity sensor
• HC-SR501 PIR motion sensor (optional)
• 10k resistor

secrets.h

Rename the secrets.example.h file to secrets.h and update the variables accordingly. An explanation of these variables can be found below

Secret	Usage
WIFI_SSID	SSID of your WiFi network
WIFI_PASSWORD	Password for the WiFi network
MQTTUSERNAME	Username for an user on the MQTT server that you want to publish to
MQTTPASSWORD	Password for the above user on the MQTT server that you want to publish to
ROOT_CA	Root CA certificate of you MQTT host
CLIENT_CERT	Client certificate registered with your MQTT host
CLIENT_KEY	Client private key matching the public key registered with your MQTT host

Other non-secret variables to consider are:

Variable	Usage
DHT_PIN	GPIO pin connected to the data pin of the DHT11 sensor
MOTION_PIN	GPIO pin connected to the data pin of the motion sensor (optional, see MOTION_ENABLED variable)
READING_DELAY	Delay between readings (milliseconds)
WIFI_RECONNECT_DELAY	Delay between reconnects to the WiFi router if a connection cannot be established
MQTT_RECONNECT_DELAY	Delay between reconnects to the MQTT server if a connection cannot be established
MOTION_ENABLED	Boolean value to enable/disable the motion sensor readings
SENSOR_ID	An ID for the sensor to differentiate between readings from multiple sensors
TEMPERATURE_TOPIC	MQTT topic to publish temperature readings to
HUMIDITY_TOPIC	MQTT topic to publish humidity readings to
MOTION_DETECTED_TOPIC	MQTT topic to motion detection messages to

Todo

• Publish motion sensor readings to MQTT
• Add circuit diagram