Jumping Flash locations inside a single application

If you want to place code at a known address, you can define a code segment and tell the linker to locate that segment in a specific location. The specifics on how to do this, #pragmas and the like, should be easy enough to determine from your toolchain documentation. The advantage of this approach is you won't be playing tricks on your toolchain so it will be able to take care of all the housekeeping details for you.

Hi all ,

I know its a bad idea but badly we need that for testing purpose. I want to test IAP commands.Actually iam using IAP for my updation of code. With IAP i can flash the new code in new flash sector apart from the currently running main(). Once the IAP process gets finished I will jump to the new location from main(). This is the purpose.

And I have checked ((void (*)(void))0x12345678)();which helps in jumping to that flash location .

Just forgot the above and now

what i need for my testing is how to instruct the keil compiler to flash the various instructions at various locations.

For eg: consider the same program at the thread starting.

In that i want to flash printf("Hai") in one flash location(eg:0x00006000) and the second printf("Bye") in another flash location(0x00008000).

I will use the((void (*)(void))0x12345678)();for jumping from to theseinstructions.

Just i need to know how to make/flash those printf instructions to reside in that particular Flash locations using the KEIL compiler.???????????????????

In that i want to flash printf("Hai") in one flash location(eg:0x00006000) and the second printf("Bye") in another flash location(0x00008000).

Either you are bad at explaining what you are trying to do, or you are trying to do it horribly wrong.
The right way to build firmware update functionality is to split your firmware into two separate programs: the bootloader and the main application.
I believe this has been discussed here a number of times. Just use search.

simply the algorithm for main function.

                  main()
                      {
                       statement 1
                       Branch to flash location 1(0x00002000).
                       statement 2 at flash location 1(0x00002000)
                       Branch to flash location 2(0x00003000)
                       statement 3 at flash location 2(0x00003000).
                       }

Simply my question is how to put those statement 2 & 3 in those flash locations??

I can use IAP to put those stmts but is there any other way through keil ??

If possible guide me to the correct link for my understanding.

In reality, you are trying to solve an invalid problem.

You can have the linker place a function at a specific memory address. But that function will be part of your program so the program will just be fragmented. That is why the linker configuration file is called a scatter file.

But your example program is not applicable for a real program spreading downloadable modules to different regions of the code memory. You just have too huge issues with implementing it for real since the compiler/linker will make use of runtime library functions, global variables etc that will move around for different builds.

If you do want bootloader + application then read up on that. But that is completely different from what you outline above. The concept of callable functions (note the difference between jump and call...) works best when the functions are written in assembler, giving you 100% control of the assumptions each function makes.

I thionk this is the old nugget "sharing routines between boot and app"

there is only one answer: DONT

Erik

As I did write in previous post: Sharing routines normally requires assembler code to make sure that the developer don't have to suffer from unknown global variables or helper library functions that are linked at different locations in the different builds.

Sharing routines can work. But it so very often fails badly. When it works, it wasn't developed by someone who starts the project by asking on a forum how to do it.

Just such a thing as printf("hello world"). printf() sounds like one function. But it has a large backend of helper functions. And depending on implementation, it may not be fully reentrant but may have global state variables that must be stored at a specific address.

And why have a printf("hello world") stored at a specific location when it's enough to just store the string "hello world"?

Sharing routines can work. But it so very often fails badly

an assumed situation:

someone ask me "to save memory, can we share routines between boot and app"

with decades of experience, my answer will be:
"sure, but first you must sign this document stating that I am not responsible for whatever ill effects that may pop up resulting from this"

Erik