Decode Multi Telem Packets to Frsky Telem Packets

[ampmam]

Since the Radiomaster TX16S has uninverted UART it eliminates the need for an inverter cable, it would be good to decode Multi Telem Packets to Frsky Telem Packets when using Internal Multi Procotol module with Frsky protocol. Here are my two use cases one working and another not working.

1. I am on OpenTX firmware 2.3.11
2. Bluetooth HC05 is configured for the baud rate 115200 using Arduino
3. Bluetooth HC05 is connected on UART1. Enabled HARDWARE>Max bauds 115200, Serial port (TTL) Telem Mirror in Radiomaster Tx16S. (benefit of using UART port in TX16S, it does not need inverter cable)
4. When I use R9M, I get full telemetry data on the Telemetry Viewer app but when I use Internal RF Multi Frsky D16, I do not get any telemetry data on the "Telemetry Viewer" app. I tried changing the baud rate from step 2 to 57600 but no luck.

As I posted my issue in the Opentx Github, it was suggested that using the internal MPM Frsky D16 protocol, the Telemetry Viewer app is unable to strip multi telem packets, probably the developer can look into this.

[porlock]

Any update on that ? had the same issue.

[Maarten112]

I noticed the same today and have been busy lately with checking the packets that the multimodule outputs. FrSky Sport frames are almost the same, but slightly different. It is explained in https://github.com/pascallanger/DIY-Multiprotocol-TX-Module/blob/master/Multiprotocol/Multiprotocol.h starting on line 1160.

MultiModule S.Port protocol frame explanation

• First byte: 0x02 [a S.Port telemetry frame received by a multimodule will get a byte with 0x02 in front of it (Type 0x02 Frksy S.port telemetry)]
• Second byte: 0x09 [frame length of payload]
• Third byte: 8 bit Sensor ID [original Start and stop byte (0x7E) from the usual s.port frames are stripped by the multimodule.]
• All other frame data is the same as on the non modified S.port telemetry frames:
  [0x10 8 bit frame header] - [value_type 16 bit] - [ value 32bit] - [ checksum 8 bit]

This is a capture of a MultiProtocol S.Port Telemetry Frame:

With this information, it's really easy to adjust the currently used decoder in https://github.com/CrazyDude1994/android-taranis-smartport-telemetry/blob/master/app/src/main/java/crazydude/com/telemetry/protocol/FrskySportProtocol.kt

Updated code
All the decoder code is there already, it should only be adjusted to reflect a different START_BYTE (0x02), skip the next byte and parse the rest like normally. Datastuffing can be ignored, since multimodule S.port telemetry doesn't use it!

I'm available for testing! Just contact me.