Martin Jerry MJ S01 - FengtianGu/Sonoff-Tasmota GitHub Wiki
Info on the Tuya The chip inside is a Tuya TYWE3S. It replicates the capabilities of an ESP8266 plus some other functionality.
It's similar to the Martin Jerry Dimmer MJ-SD01.
Generic (18)
D3 GPIO0 Button1
D3 GPIO1 Serial Out
D3 GPIO2
D3 GPIO3 Serial In
D3 GPIO4 Relay3i (31)
D3 GPIO5 Relay2i (30)
D3 GPIO12 Relay1 Relay1 (29)
D3 GPIO13 Led1i Button1 (17)
D3 GPIO14 Sensor
D3 GPIO15
D3 GPIO16
I hope this can help someone.