Flashing the Sonoff TX/T0 US Version

The latest version of the Sonoff “smart” light-switch, the TX, is significantly different from the older ones. For a start, Itead have taken notice and created the front-panel for the US version in portrait, rather than landscape orientation. However, as one of the other changes was to remove all of the graphics (barring a small “Sonoff” label along the bottom), the orientation hardly matters now, anyway.  There’s also a black version available (and the Itead  site photo of the new, graphics-free front panel with blue, LED backlighting shows this version).Black version showing switch back-light

The new, plain white (or black)  front panel is fairly thick, with a single slot on the bottom edge for levering it open from the main body of the switch  —  which is required before you can fit it in the wall. The thickness of the front panel means that removing it from the body before it is fitted into the wall is a little difficult; while the front panel doesn’t flex, the thinner plastic of the body twists alarmingly. The best way to overcome this seems to be to lay the whole device on a flat surface, face down, then firmly press down with one thumb on the screw mounting hole (on the back-plate, just above the slot) before using a large, flat-bladed screwdriver to lever the back-plate away from the front panel. It does take quite a bit of force to open it.Press firmly & lever open

Removing the front panel allows you to screw the main body into the wall cavity, but also gives us access to the PCB so that we can flash TASMOTA onto the ESP8285 controller before fixing it into its permanent home.

The top PCB (with the switches and the ESP8285) needs to be disconnected from the main body of the device before programming and pulls off fairly easily (the design is asymmetric, so the PCB can only be inserted back into the body in one way).  The PCB layout also seems to have changed quite a bit since the previous version and there’s no “TP2/GPIO0” test point on the reverse side of this board.  Luckily, the other common connection point, the pad on R19, is still available, but in a different position on the PCB.Position of GPIO0 on R19

GPIO0 is on the end of R19 which is closest to the ESP8285 chip (the larger of the two chips, on the R/H side of the photo).

The contacts for a (3.3 volt) USB adapter are visible on the bottom, R/H side of the PCB photo (click to enlarge) and, as usual, GPIO0 needs to be briefly connected to ground when powering up the device to put it into programming mode.  I just used a flying lead clipped to ground at one end, touching the other end against the resistor pad while connecting the 3v3 supply.  Programming instructions for the “T1” version of the switch still work for this version.

Version 7 of TASMOTA is now available and the template for the T1/TX is also available from GitHub,  simply choose the correct template for your specific device and copy the string from the web page, then select Configure->Configure Other from the main menu on your newly installed device, paste the text into the Template input section, tick the Activate box and hit save.  Once the ESP has rebooted you will see the toggle boxes for each of the individual switches at the top of the main menu.