ESP Relay Board

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  • Based on ESP-12F ESP8266 Wifi Board
  • This relay board use one AC input, and supports two relay AC output
  • Use mature AC-DC power module
  • Plastic enclosure design support, package includes the plastic case
  • Two Lead out buttons BTN1 and BTN2
  • Two relay indication LEDs
  • One status LED, indicating connecting status in demo code
  • Resevered design for temperature sensor DHT22
  • Screw terminal which are easy for wiring output


Lead out pin

  • IO4 and IO5 hs pull up resistors for IIC bus to use
  • Demo code for IIC OLED screen for LUA can be found at nodemcu github, /master/lua_examples/u8glib/ this folder, or click here to browse.
  • To remove the pull-up resistor, find the 2x two-very-close-pin on the right side of break away header pin 4 and pin 5, use knife to cut them, then 4.7K resistor will be disconnected. Also can add solder to re-connect them later.

DHT Sensor

  • DHT22 support plug on to use, feel free to use wires or socket to settle the DHT sensor, pin definition is 3V3, data, NC and GND
  • Default firmware has DHT module enable, upload example code will work directly. demo code here., or download lua sketch, in esplorer run DHT22.lua direct to read temperature humidity

Hardware Update Logs

Update R1.6

Update ESP Relay Board R1.6.jpg
  • Optmized lead out pins, IO4, IO5 used for IIC bus, see the demo image here.

Updated R1.5:

  • Optimized board layout, replace a few higher quality parts

Updated version R1.1:

  • Fix isolation and current drop issue on old version, which cause the ESP-wifi board may have a 5% chance to reset/restart when you switch relays On/Off very very frequently.  R1.1 version is not absolutely can be eliminated this issue since the onboard AC-DC module has a limit, but the probability of this problem should be controlled to the least, low to one percent.
  • Maximum trace design for current passing, 2MM trace width to let 2A current pass through roughly for two relays together, so either 2A for running one channel device or 1A for two device. also open trace without soldermask, you can add more solders to get even higher current passing.


B004 box.jpg
  • Case size see on the image.


Debuggin mode:

  • No need to use AC main power.
  • Connect USB-TTL tool 3V3 or 5V, GND, TX and RX to board 3V3 or 5V, GND, RX and TX.

Enter into flash mode:

  • No need to use AC main power.
  • Hold down the BTN2 button, remove/disconnect 5V/VCC pin of your USB-TTL programmer, now board power off, and reconnect this wire to power on, in the mean time, the BTN2 button must be hold down and release at least 3 seconds later after power up boot.

Use with arduino

  • Choose "Nodemcu 1.0 board", flash size 4M (3M SPIFFS), cpu 80mhz, baudrate should be 115200~916200, 115200 is most stable.
  • Change baudrate will also need formating SPIFFS, took time on module boot once.
  • You can still use ESP Download tool on max speed 1500000 to upload a full bin file later.

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