Eachen ST-DC4 Relay Board
Eachen ST-DC4

Available from:


Install method:
USB to Serial

GPIO #Component
GPIO00 Switch 1
GPIO01 User
GPIO02 User
GPIO03 User
GPIO04 Relay 3
GPIO05 Relay 2
GPIO09 User
GPIO10 User
GPIO12 Relay 1
GPIO13 LedLink
GPIO14 User
GPIO15 Relay 4
GPIO16 User
GPIO17 None

Serial Flashing

Flash the Tasmota firmware.

  • Get the latest Tasmota firmware.
  • Use Tazmotizer for flashing via serial interface.
    • Start Tasmotizer.
    • Select Serial Port.
    • Check Save original firmware.
    • Pick 1 MB from dropdown list.
    • Select BIN radio button.
    • Open latest Tasmota firmware from above.
    • Check Erase before flashing.
  • Connect USB to serial interface from computer to board with 3v jumper selected.
    • Connect to board as follows.
USB Adapter Eachen Board
  • Power up the Eachen Relay board with the #1 Relay button held down.
  • Continue holding the #1 Relay button down during the entire flashing process.
  • Hit blue Tasmotize! button in Tasmotizer.
  • After a minute or so the Eachen board will reboot into new firmware.
  • Unplug power from Eachen board. Wait 5 secs then replug power.

    Connect to WIFI

  • Using WIFI capable device connect to AP labeled tasmota_XXXXXX.
    (where XXXXXX is the last 6 digits of the device’s MAC addr.)
  • Once connected go to
  • Enter your WIFI information into AP1 SSID and AP1 Password and check the box beside password.
  • Hit Save.


  • Go to your Router Admin page.
    • Look for IP address of device named tasmota_XXXXXX.
      (where XXXXXX is the last 6 digits of device’s MAC addr.)
  • Enter the IP address from above into a web browser.
  • Go to Configuration, Other
    • (This step:
    • configures the device’s parameters including TuyaMCU serial COMM and 4 dummy relays used in the Rules below)
  • Copy
  • Paste into Template field.
  • Check Activate box.
  • Hit Save.
  • Device will reboot.
  • Go to Console
    • (This step sets up:
    • 9600 baud rate with so97 0
    • enables MQTT with so3 1
    • publishes TuyaReceived messages to MQTT with so66 1
    • keeps momentary timing slider from turning off dummy relay9(BUS) with so77 1
    • keeps momentary timing slider from turning on dummy relay9(BUS) with so20 1
    • assigns the Tuya MCU serial relay devices to Tasmota devices
      • relay1 with tuyamcu 11,1
      • relay2 with tuyamcu 12,2
      • relay3 with tuyamcu 13,3
      • relay4 with tuyamcu 14,4
      • all on function with tuyamcu 15,13
      • momentary timing slider with tuyamcu 21,103)
    • Copy
      backlog so97 0;so3 1;so66 1;so20 1;so77 1;tuyamcu 11,1;tuyamcu 12,2;tuyamcu 13,3;tuyamcu 14,4;tuyamcu 15,13;tuyamcu 21,103
    • Paste into Console’s Enter command space.
    • Device will reboot.
  • Go to Console
    • (This step sets up:
    • an interlock on dummy relays 6(SLM),7(MAM),8(ILKM) so only 1 relay mode may be selected with interlock 6,7,8 and interlock 1
    • 0 to 60 secs timing on momentary timing slider with dimmerrange 0,600 and dimmerstep 5)

    • Copy
      backlog interlock 6,7,8;interlock 1;dimmerrange 0,600;dimmerstep 5
    • Paste into Console’s Enter command space.
    • Device will reboot.
  • Go to Console
    • (This step:
    • names all the WebUI buttons using the first Copy/Paste
      • ALL = ALL ON button
      • SLM = Self Lock Mode (any number of relays remain ON until turned OFF)
      • MAM = Momentary Mode (uses Dimmer Slider to set ON time length from 0 to 60 secs)
      • ILKM = Interlock Mode (Only 1 relay can remain ON at a time)
      • BUS = Boot Up State (Do all relays remain OFF or turn ON when power is applied to board)
    • creates Rules to be used for
      • Boot Up State with Rule1 and
      • Relay Mode with Rule2
        using the second Copy/Paste)
  • Copy
    backlog webbutton5 ALL;webbutton6 SLM;webbutton7 MAM;webbutton8 ILKM;webbutton9 BUS
  • Paste into Console’s Enter command space.
  • Copy
    backlog rule1 on power9#state=1 do tuyasend1 101,1 endon on power9#state=0 do tuyasend1 101,0 endon;rule1 1;rule2 on power6#state=1 do tuyasend4 102,0 endon on power7#state=1 do tuyasend4 102,1 endon on power8#state=1 do tuyasend4 102,2 endon  on tuyareceived#data=55AA03070005660400010079 do power6 1 endon  on tuyareceived#data=55AA0307000566040001017A do power7 1 endon  on tuyareceived#data=55AA0307000566040001027B do power8 1 endon;rule2 1
  • Paste into Console’s Enter command space.
  • Device will reboot.
  • optional - Go to Console
    • (This step:
      • names all the devices)
    • Copy
      backlog devicename tasmota_relay01;friendlyname1 tasmota_relay01-1;friendlyname2 tasmota_relay01-2;friendlyname3 tasmota_relay01-3;friendlyname4 tasmota_relay01-4;friendlyname5 tasmota_relay01-all;friendlyname6 tasmota_relay01-slm;friendlyname7 tasmota_relay01-mam;friendlyname8 tasmota_relay01-ilkm
    • Paste into Console’s Enter command space.