ESPDoubleRelayBlink

this is a simple example of how to use the ESP8266 serial double relay board from aliexpress with arduino firmware.

Important bits

(im disabling the RX pin to use it as a regular GPIO pin for sensors or peripherals, which is sometimes not recommended)

Serial.begin(115200, SERIAL_8N1, SERIAL_TX_ONLY);

Then the relays, these are controlled via Serial.write();

Here is Relay0:

// Relay0 on
Serial.write(0xA0);
Serial.write(0x01);
Serial.write(0x01);
Serial.write(0xA2);
  
// Relay0 off
Serial.write(0xA0);
Serial.write(0x01);
Serial.write(0x00);
Serial.write(0xA1);

Here is Relay1:

// Relay1 on
Serial.write(0xA0);
Serial.write(0x02);
Serial.write(0x01);
Serial.write(0xA3);
  
// Relay1 off
Serial.write(0xA0);
Serial.write(0x02);
Serial.write(0x00);
Serial.write(0xA2);