Tasmota on Sonoff S31 using NodeMCU

ESP8266 (Sonoff S31 Outlet) and ESP8285 (Sonoff Basic)

• Disassemble: Remove grey Cap with spooger (or equivalent), then unscrew three obvious screws, slide out 'slides', pull off cover
• Attach Serial Communication Cables ( x 4), from closest top corner of PCB: VCC, RX, TX, skip, skip, Ground (IE that's what's printed on the PCB)
  • Use Red - Yellow - Green Color combination on connector cables, like a Stop Light, if it helps to keep things sorted.
• Plug in Serial Communication Device (TTL), but FIRST: "Push the Button Max!" (to put the Sonoff device into 'Flash Mode')
• Start NodeMCU: Set Serial COM Port, Select .bin file, Dual Output (DOUT), yes, wipes all data
• ...wait
• Unplug Serial Communication Device and plug it back in (IE, restart / reboot Sonoff / Tasmota device), no need to plug it into 120V, power comes through Serial Communication Device.
• Look for Tasmota (or maybe Sonoff for older firmware) with a WiFi Device (Computer or Phone or Whatever) and connect
• Most devices will automatically open a Browser window, if not, look for WiFi IP Address and associated Default Gateway (should be the Sonoff / Tasmota device), navigate to that IP Address (192.168.4.1 on newer firmware, as of 01.2025).
• In Web GUI for Sonoff / Tasmota device, connect to a WiFi Network.
• WAIT, it takes a bit to restart (under 11 seconds)
• If Sonoff / Tasmota device connects successfully, it should display new IP Address (of local WiFi network Sonoff / Tasmota device is connected to) and should then redirect to that same IP Address. Whatever WiFi Client Device was connected to Sonoff / Tasmota device will be disconnected.
• WAIT, it takes a bit to restart again (under 11 seconds)
• TIP: If moving a Sonoff / Tasmota device to another "LAN", it is usually safer to configure the "new LAN's" WiFi Access Point (if using something like OpenWRT) with the Sonoff / Tasmota's 'previous' WiFi AP SSID and Password, then reconfigure the Sonoff / Tasmota to connect to the new WiFi AP
• OR, configure the secondary WiFi AP info (SSID / Password) within the Tasmota / Sonoff GUI.

https://www.youtube.com/watch?v=08_GBROKQH0

https://www.adventurousway.com/blog/sonoff-s31

Downloads

Make sure it is for the ESP8266 "SOC" / "CPU" IC (not ESP32, etc)

Downloads: http://ota.tasmota.com/tasmota/release/

Other Downloads: https://github.com/arendst/Tasmota-firmware/tree/firmware/release-firmware/tasmota and https://github.com/arendst/Tasmota/releases

Upgrading, just so it is known...

Due to limited storage space, the pattern observed is as follows;

• Tasmota is currently / successfully installed
• Upgrade process started ('online' version)
• Minimal version is installed
• possible reboot occurs
• Basic version is installed (AKA 'full version')