A couple of months ago, I received an Itead Studio Sonoff and Slampher module that are meant for some home automation by using their app (and platform). I’ve made some short videos about the modules and a dissasembly. Because both modules run on the ESP8266 chips, reprogramming them with custom firmware seemed obvious. Itead even made it that easy that they provided a 4 pin header (there are now modules with 5 pin headers, but I believe I received some old versions. Mine include the 433 RF functionality).
After much experimenting, I could not get the boards (both Salmpher and Sonoff) in flash mode (program mode). This was highly frustrating as all the other people seemed to be able to! So WHY was it not working? Checking many websites, the instruction was always the same: Hold the button, plug in the USB interface, set the programmer tool to 1MB of flash and program the board. Frustrating, it didn’t work. The boards did not go into program mode!
After much more searching, I encountered a comment on Peter Scargill’s blog post from Alberto Avina. After trying out this little trick on my Slampher module, it worked!!! Finally I could follow the standard instructions and flash new firmware. He only mentioned the Slampher fix, but my Sonoff was behaving the same. Therefore, the search began on the Sonoff board which resistor they forgot (or on purpose) did not install. The search was finalized quickly by using the Sonoff schematic (R21 towards the E-FW or GPIO0).
After putting a little wire on both footprints, both the boards now work! For your reference, I have attached pictures of which resistors to fill in.