I bought a couple of Sonoff S26 Wifi-plugs. These are built with an ESP8266 wifi chip and can be programmed with custom firmware.

I wanted to flash them with Tasmota firmware and didn’t want to solder wires to every one,  so I made a pogo-pin flash adapter 🙂

I built it to be used with my FTDI USB to TTL Serial converter. The one I got, have 3.3V pins for communication(RX/TX, etc) and 5V for power. The ESP8266 chip needs 3.3V for both power and GPIO’s so I designed the flash adapter to contain a voltage regulator (FTDI 5V -> Voltage regulator -> 3.3V Sonoff ESP8266).

This features:

• Solderless flashing of Sonoff S26
• Easy to use
• Power ESP from USB
• FTDI USB to 3.3V Serial TTL cable – compatible.

Whats needed:

• 3D-printed parts, STL’s can be downloaded from my Thingiverse.
• Pogo-pins, P100-E2, Diameter: 1.36mm, Length: 33.3mm.
• Voltage regulator, HW-108, 20x20mm.
• FTDI or similar, USB to TTL 3.3V Serial cable.
• Sonoff S26 Wifi plug.
• 3pcs small screws for the top lid.
• 6pin – pin-header.

Disclamer:

• I take no responsibility if you build this or use this!
• Use it at your own risk!
• Never plug the Sonoff S26 in to mains power when you have take it apart!

Build it:

1. Print the needed parts.
2. Attach pogo-pins.
3. Solder wires to voltage regulator. (If you have a USB to TTL serial cable which can supply 3.3V, you can skip the voltage regulator and solder wires for 3.3V and GND directly from pin header to pogo-pins and skip step 4).
4. Solder voltage regulator wires (5V and GND (IN) to pin-headers and 3.3V and GND (OUT) to pogo-pins).
5. Solder wires for RX and TX to pogo-pins and pin-header.
6. Check all connections and make sure everything is correct.
7. Attach FTDI-cable and adjust output voltage from voltage-regulator to 3.3V.
8. Use some hot glue to hold pogo-pins and pin-header in place.
9. Attach the lid.
10. Finished! Time to flash 🙂

How to use the flash adapter: