topic AN4329 Copy function to RAM and execute from RAM (frdm-k64 example project) in Kinetis Microcontrollers

AN4329 Copy function to RAM and execute from RAM (frdm-k64 example project)

jacobjennings — Fri, 13 May 2016 02:43:58 GMT

Hello,

Based on AN-4329, I assembled a test project (attached) for the FRDM-K64F which attempts to copy a function to RAM and run it, but I am getting a fault when attempting to call the function. The Source and Destiny variables seem to be in the correct ranges in copyToMyRam, but the call fails.

AN4329 - NXP

Note changes in the ProcessorExpert.ld file, and main.c

Any advice is appreciated! It seems very close.

Thanks,

Jake

Original Attachment has been moved to: test-run-from-memory-frdm-k64f.zip

Re: AN4329 Copy function to RAM and execute from RAM (frdm-k64 example project)

mjbcswitzerland — Fri, 13 May 2016 10:56:48 GMT

Make sure that you are creating a thumb-comform copy of the code in SRAM since if it i not correctly aligned it will fail.

Below is an example where fnFlashRoutine() is a small subroutine to be copied to SRAM and later executed by calling fnRAM_code()

Regards

Mark

	#define PROG_WORD_SIZE 30	// adequate space for the small program
	int i = 0;
	unsigned char ptrThumb2 = (unsigned char )fnFlashRoutine;
	static unsigned short usProgSpace[PROG_WORD_SIZE] = {0};	// make space for the routine on stack (this will have an even boundary)

	ptrThumb2 = (unsigned char *)(((CAST_POINTER_ARITHMETIC)ptrThumb2) & ~0x1); // thumb 2 address
	while (i < PROG_WORD_SIZE) {	// copy program to SRAM
	usProgSpace[i++] = (unsigned short )ptrThumb2;
	ptrThumb2 += sizeof (unsigned short);
	}
	ptrThumb2 = (unsigned char *)usProgSpace;
	ptrThumb2++;	// create a thumb 2 call
	fnRAM_code = (void()(volatile unsigned char ))(ptrThumb2);

Re: AN4329 Copy function to RAM and execute from RAM (frdm-k64 example project)

jacobjennings — Fri, 13 May 2016 23:23:49 GMT

I got things working and wrote up a summary here:

Jake Jennings on Twitter: "Leverage the GNU ARM linker to relocate and execute code from RAM https://t.co/r2NOcOnZsM"

Jacob Jennings Tech • Leverage the GNU ARM linker to relocate and...

Code here: GitHub - jacobjennings/gnu-arm-execute-from-ram-example: Demonstrate linker file and process for selectively moving func…