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.
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.