The MultiTRX is a small USB RF transceiver made to control cheap remote power switches and decode various sensors operating at 433,92 MHz. The project originates back to 2011, and was one of my first serious microcontroller projects. I have now decided to make the project open source, and at the same time releases a new firmware almost 5 years after the previous firmware was released! See "firmware/1.3/CHANGES" for details.
- Nexa self learning system (decode, encode)
- Nexa code wheel system (decode)
- Kangthai power switches (encode)
- GAO power switches (decode, encode)
- Waveman power switches (encode)
- Doro PIR and door sensors (decode)
- Esic temperature sensors (decode)
The project is made in Microchip MPLAB X with XC8 compiler. Firmware 1.3 can be flashed to a MultiTRX hardware 1.1 (red PCB). Hardware 1.0 (green PCB) is not supported in the latest firmware because the transceiver data pin is not connected to an interrupt pin on the microcontroller. Allowing non-interrupt-driven timing for legacy devices can easily be done by looking at how timing is done in firwmare 1.2. Now it's all open source, so feel obligated ;)
To upload the firmware, use one of the two methods below:
- Connect a PIC programmer to the six exposed pads on the MultiTRX (while powered)
- For most devices sold, the microcontroller is flashed with a bootloader. Upload the ".hex"-file from "firmware/1.3/multitrx.X/dist/default/production/" using the "ds30 Loader" bootloader and instructions in "firmware/bootloader-and-compiled/"
With firmware 1.3, the MultiTRX can forward raw samples from the ASK transceiver. This is very useful for reverse engineering more protocols.
- Verify port name and run the python program "reverse-engineering/mtrx-raw.py"
- When a sequence of bits is received above the noise level, the bit timing is printed and a plot will open in a new window
- Close the plot to allow for a new sequence to be received
Check out the add-on for HomeGenie in the subfolder "homegenie-addon".
The easiest way of controlling your remote power switch is to keep your (already paired) remote control close to the MultiTRX and copy the string received, eg. "$GABC2F0". This way you can switch on and off this device by sending "$GABC2F1" and "$GABC2F0", respectively.
If you want to pair a GAO device with the MultiTRX directly, send the string above, but replace the power on/off parameter with the number two: $GABC2F2.
Nexa dimmers has the great feature of being able to dim to an absolute level in 16 steps. To do so, replace the power on/off parameter with the number two, and add an extra hexadecimal character (upper case) with the dim level: $N1234ABC030 -> $N1234ABC032F (will set the device to maximum brightness). Complete command list
All communication is done at 8N1 9600 baud (115200 baud for firmware 1.3 due to raw mode requiring higher data rate), ASCII-formatted data. Data sent to and received from the board is terminated with LF (ASCII character 10) or CR (ASCII character 13). All hexadecimal characters must be in upper case!
| Output | Description | Example(s) |
|---|---|---|
| $Dddd | Doro Secur sensor. d = dip switch settings (hex). | $DA07 |
| $Eh,c,t,H,b | Esic temperature sensor. h = house code, c = channel, t = temperature (degrees Celsius), H = relative humidity (percent), b = low battery indicator (0/1). | $E5,1,12.3,71,0 |
| $GiiicCp | GAO remote power switch. i = unique ID (hex), c = channel, C = checksum, p = power setting (0/1) | $GABC2F0 $GABC2F1 |
| $Niiiiiiigcp | Nexa remote power switch. i = unique ID (hex), g = group enable (0/1), c = channel (hex), p = power setting (0/1). Packets with dim level will not be received! | $N1234ABC010 $N1234ABC011 |
| Input | Description | Example(s) |
|---|---|---|
| $GiiicCp | GAO remote power switch. i = unique ID (hex), c = channel, C = checksum, p = power setting (0/1) and pairing mode (2) | $GABC2F0 $GABC2F1 |
| $Niiiiiiigcp[l] | Nexa remote power switch. i = unique ID (hex), g = group enable (0/1), c = channel (hex), p = power setting (0/1, absolute dim level = 2), l = dim level (hex). Dim level only applies if p = 2, so the length of this string varies. | $N1234ABC010 $N1234ABC011 $N1234ABC012F |
| $Whuup | Waveman remote power switch. h = house code (A-P), uu = unit code (01-16), p = power setting (0/1) | $WA011 |
| $Kssssscp | Kangtai remote power switch. s = system code dip switch (0/1), c = channel (A-E), p = power setting (0/1) | $K00001A1 |
| $Bd | See above. | - |
| Input | Description | Example(s) |
|---|---|---|
| $S | Print all settings. Settings can be changed by typing the character shown in brackets after typing "$S". | - |
| $P | The MultiTRX will respond with version number | - |
| $X | Force restart. Primarily used to upload new firmware with bootloader. | - |
| $Sp | Execute setting p (for commands with no value) | $SF (to load defaults) |
| $Spv | Set setting "p" to value "v" | $SD0 (to deactivate Doro-reception) |
-- Jon Petter Skagmo, LA3JPA