使用jtag编程sam4e时如何防止启动区域

Question

I am using at91sam4e16e and working on bootloader. boot region is defined at 0x400000 and application region is at 0x420000 onwards.

i have downloaded bootloader code into that region and compiled application code with 0x420000 link address. now I want to download that application to 0x420000 using Jtag but when I download it, all the memory goes erased and only application remains.

In avr, I could prevent the boot area in debugger option; How to do the same in sam4e?

regards, shreyas.

Answer 1

Go to project options.

In Debugger -> Images you can download extra image.

Note that I have only used this with the Debug info only -option enabled, but I have bundled bootloader with my app, so it is a bit different situation. (You can bundle bootloader in Linker -> Input tab.)

I also had a problem that since application wasn't in normal starting location, I had to initialize program counter, and stack pointer registers manually. You can do this by defining a macro file in Debugger -> Setup .

Macro file could look like this (note that this is for different MCU, so you may have different registers/addresses):

execUserReset() 
{
    // Set the stack pointer
    MSP = *(int*)0x00008000; 
    // Set the program counter
    PC = *(int*)0x00008004; 
}

This macro file skips bootloader when using debugger reset, but you could also make macro file which enters bootloader on reset by using different addresses.

Edit: Bundling the bootloader:

It's been a while since I have done this, so hopefully I remember everything.

You need to add your bootloader .bin file to Linker -> Input -> Raw binary image . Also define symbol bootloader , and section .bootloader . (I think alignment needs to be specified too, even if you use absolute placement.)

Add your bootloader symbol to Keep symbols: box above. This should make sure that bootloader is always included.

In your linker file, add line

place at address mem:0x00000000 { section .bootloader };

to place bootloader at specific address (change address to match your bootloader address).