This page describes the first version of the ESP8266 relay board. For the newer version which includes a usb-serial converter click here.
- 2 relays
- DHT22 temperature and humidity sensor
- GPIO and programming header
- On board LM1117 linear voltage regulator (3.3v)
Note: R2 and R5 should be left unpopulated. These two resistors can be used as pulldown resistor for the gpio pins if the output indication leds are not installed.
The firmware that I originally made for this project has become outdated. You can still try to use it but I reccomend programming your own firmware for the board using the Espressif SDK or Arduino.
Programming the board
To program the firmware into the ESP8266 an external usb-serial adapter is needed.
Connect the ground, RX and TX of your usb-serial converter to the correct pins on the board (see schematic).
Remove power from the board and press button 2 (see picture). Now switch the power on again while holding button 2. The ESP8266 has now started in firmware downloading mode.
For Windows a tool like nodemcu-flasher can be used to flash the firmware. For linux I suggest esptool, which is included with the example firmware that you can find on this page.