This article documents a first project with the Espressif ESP8266 in its second evolution.
The objective is a module that will take periodic temperature and humidity measurements and publish them to an MQTT message broker.
This inital implementation is very basic, it is largely configured in code, though it does use DHCP. Later extensions might include a web interface for configuration of WLAN parameters etc, but for the moment the emphasis is assessment of reliability given some reports on the ‘net.
Evolution 2
The original design embedded key configuration variables in the main source code for simplicity in getting the code working.
Evolution 2 separates configuration variables from code, and provides a web interface for configuring the most common variables. The screenshot above shows the configuration screen including the use of a datalist on the SSID input field.
Hardware
A module was purchased with on board CP210x USB to serial chip. The only other component needed was the DHT22 digital temperature and humidity sensor.
NodeMCU was chosen for the ESP2866 firmware because of the inbuilt support for ‘interesting things’, including the DHT22.
Above is a breadboard of the system for development. The board had a 4MB (32Mb) flash chip on it. Continue reading ESP8266 IoT DHT22 temperature and humidity – evolution 2