Preparing Sonoff Slampher for Firmware Modification

As discussed in our Guide Sonoff Smart Switch LAN Control without Internet, Here is how to prepare WiFi Smart Light Bulb Holder Sonoff Slampher RF for installing our opensource firmware to control it locally without internet. Follow the steps below to connect the device with PC.

Note: Always unplug the Sonoff device from AC Power Source before start working with it.

Step A:

Unscrew the two screws found on the rear side of Sonoff Slampher using screw driver and lift the upper lid. Take the PCB out carefully without pulling the wires connected to it.

Step B:

Install a male or female header on holes given for programming the device by soldering it permanently for a firm connection. Header without soldering will result in loose connection and uploading may fail.

The Sonoff Slampher have an 8bit EFM8BB10F2G-A-QFN20 microcontroller that listens to the radio module messages and handles the on-board button tied to GPIO-0. However, it can not be used to enter Sonoff Slampher into programming mode. For starting Sonoff Slampher in programming mode GPIO-0 should be tied to ground. For this purpose, solder a small piece of wire to ESP8285 side of resistor R9 which is directly connected to GPIO-0.



Let’s have a look onto programming header pinout. First pin which is near the 3V3 printed on PCB, is VCC followed by RX, TX and GND. Connect FTDI according to the following combinations.


FTDI Sonoff Slampher
3.3V VCC



Connect the wire solder on resistor R9, to GND and Plug the FTDI in to PC. Now micro-controller present in our Sonoff Slampher i.e. ESP8285 will start in programming mode.


Step C:

Open Arduino IDE and go to File > Examples > ESPMetRED > Examples > Sonoff_Slampher (Choose any Sonoff Sketch). Change WIFI_SSID, WIFI_PASSWORD, MQTT_SERVER, MQTT_USER and MQTT_PASSWORD according to your own.


Choose “Generic ESP8285 Module” under Tools > Board. Change Flash Size to “1M(64K SPIFFS)” and choose your Port. Click on Sketch > Verify/Compile to compile the sketch.



Once your Sonoff device starts into programming mode, upload the sketch on Arduino IDE by visiting Sketch > Upload. It will take some time to upload the firmware. One it’s done uploading, disconnect the device from PC and reassemble it according to the Step D.

Step D:

Desolder the wire connected to resistor R9 carefully. Reassemble Sonoff Slampher by sliding the PCB inside the enclosure taking care of push button correctly placing in it’s hole. Now put on the lid and tighten the screws back.

Step E:

Proceed the Step E in our Guide Sonoff Smart Switch LAN Control without Internet.

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