Custom Multiprotocol firmware on Jumper T-Pro internal 4-in-1 module (binding removed) – is it safe/expected to work?

[yasin112358]

Hello,

I have a question about using a custom-compiled Multiprotocol firmware on the Jumper T-Pro internal 4-in-1 RF module.

I know that the Jumper T-Pro already comes with a pre-installed multiprotocol firmware on its internal 4-in-1 module.
My goal is not to replace EdgeTX or modify the radio firmware itself.

This is purely an R&D / experimental purpose.

What I want to do

-Compile Multiprotocol.ino from source

-Apply small modifications to the protocol code (specifically FrSkyX)

-Remove / bypass the binding state machine, so the module starts directly in FRSKY_DATA mode

-Flash the resulting .bin firmware into the internal 4-in-1 module using DFU

Example of what I changed (simplified):

Force state = FRSKY_BIND_DONE

Skip FrSkyX_build_bind_packet()

Initialize data immediately on startup

My understanding so far

-EdgeTX runs on the radio MCU and communicates with the internal 4-in-1 module via serial

-The internal module runs its own STM32 firmware

-The compiled Multiprotocol .bin contains only RF/protocol logic, not EdgeTX or LUA

-As long as the serial protocol remains compatible, EdgeTX should continue to work normally

My questions

1-Is it technically safe and expected to flash a custom-compiled Multiprotocol firmware over the factory one on the Jumper T-Pro internal 4-in-1 module?

2-Are there any hardware-specific differences (bootloader, memory layout, pin mapping) in the Jumper T-Pro internal module that would prevent a stock STM32 Multiprotocol build from working?

3-Is bypassing the bind state machine likely to cause issues with:

EdgeTX MULTI protocol handling

Telemetry initialization

Protocol timing expectations

4-Are there any parts of the codebase where binding is implicitly assumed even if the state is forced to FRSKY_BIND_DONE?

Again, this is for research and experimentation only, not for production use.

Thanks in advance for any clarification or pointers.

[pagrey]

I think the Jumper 4-in-1 module uses the mm-stm-serial firmware or a generic stm32 version of the 4-in-1 so you can build and flash it easily. If a module has any special features it'll have it's own firmware name and not a generic one. You might want to try and flash a few different pre-compiled versions so you know the process before you flash a custom build.

You can make all the changes you want to FrSkyX_cc2500.ino or the telemetry files, as long as you leave the main bootloader code alone you'll always be able to reflash from the radio. Be sure you follow the directions and use the correct version of Arduino, 1.X.X and not 2.X.X. Before you flash make sure your new *.bin file is about the right size. If it's way to big or way to small stop and find out what went wrong before you try and flash it.

When I first starting flashing custom builds I bought an iRX4 module to test with, it's not exactly cheap but it's easier to recover from big mistakes.