Reverse-engineering a toy based on an nRF52832

RE: Reverse-engineering a toy based on an nRF52832

bjorn-spockeli — Wed, 10 Apr 2019 12:06:57 GMT

As to Q1: https://reverseengineering.stackexchange.com/questions/11650/how-can-i-decompile-an-arm-cortex-m0-hex-file-to-c. You can get hold of the assembler code, but thats about it I think

Q2: The application is linked with the SoftDevice headers, so if you update the SoftDevice you need to make sure that it is compatible with the SoftDevice present. Otherwise, the device will probably hardfault when the SD API is called from the application.

Best regards

Bjørn

RE: Reverse-engineering a toy based on an nRF52832

Frank — Tue, 09 Apr 2019 21:03:29 GMT

The chips have protection 1 (readout) enabled but not 2 so they are still erasable/writeable, but we do not have a copy of the bootloader. Can the SoftDevice be bundled with the application replaced over BLE DFU, or is that in of itself a function of the soft device and as such be in use?

The primary reason I am curious about replacing the SoftDevice is that there are several models of smartphones that fail to communicate with the toys and I was hoping to increase compatibility.

RE: Reverse-engineering a toy based on an nRF52832

Frank — Tue, 09 Apr 2019 20:57:20 GMT

https://github.com/SkyRocketToys Not a lot left there, but the Recoil_Documentation repo is the best information so far.

RE: Reverse-engineering a toy based on an nRF52832

awneil — Tue, 09 Apr 2019 20:50:04 GMT

[quote userid="74434" url="~/f/nordic-q-a/45982/reverse-engineering-a-toy-based-on-an-nrf52832"]what is left is available on GitHub[/quote]

Where?

RE: Reverse-engineering a toy based on an nRF52832

awneil — Tue, 09 Apr 2019 20:46:31 GMT

[quote userid="74434" url="~/f/nordic-q-a/45982/reverse-engineering-a-toy-based-on-an-nrf52832"]#1: Is it possible to decompile a program bin back into a semblance of human read/editable code?[/quote]

It is largely possible to disassemble binary code to assembler source, but you will have no meaningful names or labels for anything - variables, functions, etc.

For any non-trivial program, Getting back to useful, readable code at the 'C' level is pretty much a dead end.

It would probably be easier & more productive to just re-write from scratch.

[quote userid="74434" url="~/f/nordic-q-a/45982/reverse-engineering-a-toy-based-on-an-nrf52832"]can the underlying SoftDevice be updated without having to modify the application?[/quote]

It should be possible via SWD - provided the chip is not locked.

Whether a bootloader would support that is another question.

Whether the app would work with any other SoftDevice is another question still.