Building firmware with gcc

[tormod]

@Jerry

Thanks, all.
I have tried the GCC. It compiles and links fine,but the final hex file can not work.I just got a blank screen on my DSO. I am just learning about GCC,IAR and the startup code. Initially, I thought maybe the different binary file format made the issue. IAR4 uses UBROF that is IAR’s private format, yet IAR5 and GCC use ELF.
Now,I realise that is not the real reason.

Yes, the elf format is not important. The “real” binary content gets stripped out of the elf file into the bin (or dfu) file, which gets loaded on the Nano. So whether the intermediate format is elf or ubrof does not matter.

The bootloader(just IAP) was compiled by IAR4.X constantly. I used IAR5.0 to compile Ben’s code,it passed. The lib can work, app can’t. Allow me to explain the
procedure when power on. Firstly, the bootloader will run. It will detect one GPIO to determine whether or not to upgrade. If not, it will jump to the lib part.
At the end of “main” function, it will jump to start address of the app part. Using IAR5,app can not work,it means the start address of the app part is wrong.GCC can not work,I think, they have different reasons.

Exactly this issue should be fixed by the patch I suggested in viewtopic.php?p=4498#p4498. Basically the patch makes the LIB do the same when jumping to the APP, as the bootloader does when jumping to the LIB: It reads the startup entry (reset handler) from the interrupt vector instead of using a hardcoded address of the startup entry.

I have tested the patch on an emulator, so I know that it compiles correctly and does the right thing. However, I can not see if it works on gcc, so I will need some of you to please test it on IAR 4.0 and 5.0.