Hi, I would like to share my experience with setting up ESP Easy on ESP8266 with SparkFun Qwiic Single Relay and 1602 LCD display. It took me a lot of effort to search the web and analyze the source files of original CPP Sparkfun library. Unfortunately, no one has tried to connect this relay with ESP before? 
Hope this guide will be helpful to you. 
Hardware:
- ESP 8266 module
- SparkFun Qwiic Single Relay module (COM-15093)
- 1602 LCD module
Software:
- ESPEasy (Build: ESP_Easy_mega_20260121_neopixel_ESP8266_4M1M Jan 21 2026)
Both relay and LCD are I2C devices. Relay works at address 0x18, and LCD works at 0x27. I2C bus is configured to work at GPIO-4 (D2) for SDA signal and GPIO-5 (D1) for SCL signal.
List of devices:
Device 1:
Device 2:
After setting the above values you can control the system with http commands as follows (let’s assume [your_ip_address] is your local IP address of ESP):
The relay is turned on by default, due to init string.
To turn the relay off use:
http://[your_ip_address]/control?cmd=geni2c,cmd,write.u8.0x00
The result is:
The blue LED is off. The multimeter shows the resistance between Common and NO points. In this case it is “infinity”.
To turn the relay on again use:
http://[your_ip_address]/control?cmd=geni2c,cmd,write.u8.0x01
The result is:
The blue LED is on. The multimeter shows the resistance of about 1ohm between Common and NO points. The circuit is short, just as it should be.