Hello
I'm using Cortex-M3, and because of speed and peripherals, I want to use a dual core MCU.
I realized I have to write two separate code and make two separate executable file.
But I don't know how to merge these executable files.
I have to write down the executable files in separate specific region of flash?
Can anyone help me? I'm a little confused
Thank you
As allenwillson already mentioned, you can build two different executables:
You convert the Cortex-M0 executable to a hex-file and from your Cortex-M4 code, you load the image and start the Cortex-M0 core.
But there is a different way, which has not been covered in any documentation I know of.
I write all the code in assembly language; sometimes I write some files in C for the Cortex-M4, though.
But I write the Cortex-M0 code in assembly language, and I use GCC and GAS for building my project.
I recommend that the first line of your assembly file is...
.syntax unified
Somewhere you want to tell the assembler, that you're about to write Cortex-M0 code, so before your Cortex-M0 code, write the following line:
.cpu cortex-m0
... If you at some point want to write cortex-m4 code in the same source file, just switch ...
.cpu cortex-m4
Then you do not need to convert the code to a hex-file, you still need to start up the Cortex-M0 core from your Cortex-M4 code, but I find it a lot easier this way myself.
Remember: You can share your Cortex-M0 code with the Cortex-M4. The Cortex-M4 can run the Cortex-M0 code, but the Cortex-M0 cannot run the Cortex-M4 code. But you should be careful. If the Cortex-M4 is running the Cortex-M0 code, then the Cortex-M4 is stalling the Cortex-M0, because they're suddenly accessing the same memory space.
-So it's a good idea to keep the Cortex-M0 code in one Flash bank, and the Cortex-M4 code in the other Flash-bank.
(Or: You may want to run some of the code from SRAM, if it needs to run extra fast)
-See "Using GNU Assembler" for more information about what it can do.
Hi jensbauer
Sorry for the latency
How can I add M0 image(Hex file) to M4 project?
Can you please explain how to do that in assembly?
You write a text file ending in .s (or .S), and add it to your Cortex-M4 project like you would add a .c file there.
This file will now be built using the assembler instead of the compiler (.s files are built using the assembler, .c and .cpp files by the compiler).
A short example file showing most of the assembler-directives you would be using:
;/* File: example.s */
.syntax unified /* this makes the assembler automatically generate IT instructions for you */
.cpu cortex-m0 /* this selects the cortex-m0 architecture and helps you avoid using cortex-m3/cortex-m4 instructions */
.text /* this makes sure the code goes into the .text section */
.global m0vectors
.word 0x20004000 /* this defines the initial stack pointer for the Cortex-M0 */
.word m0reset /* the reset exception vector */
/* here you should place your other exception vectors. There are too many to include in this example */
.global m0test /* this exports the symbol m0test, so you can reference it from for instance C */
.func m0test,m0test /* this names the symbol m0test as a function (for the debug-info) */
.type m0test,%function /* this tells the assembler (and linker) what kind of symbol we're generating */
.thumb_func /* this is necessary if pointers use the symbol */
.align /* this makes sure the code is positioned on a 16-bit boundary */
m0test: /* this defines the actual symbol */
ldr r0,=0x01234567 /* example code, load a value into r0 */
bx lr /* return to the calling function */
m0reset:
bl m0test /* this is the startup-code, call our function */
lockup: wfi /* sleep the CPU; it'll wake up if an interrupt occurs */
b lockup /* go back to sleep */
.size m0test, . - m0test /* this tells the linker how big this function is, so it can correctly exclude it if it's unused */
.endfunc /* this marks the end of the function (for the debug-info) */
You can then refer to the code from your C file...
/* File: main.c */
#include <ipc_queue.h>
/* Note: you don't need argc and argv on a microcontroller. */
int main(int argc, const char *argv[])
{
IPC_haltSlave();
SET_SLAVE_SHADOWREG(m0vectors);
IPC_startSlave();
while(1)
asm volatile("wfi");
}
return(0);
I'm not completely sure about the .c file; I haven't tested the code, so expect a lot of errors. It would be something in that direction, though.