M4/M0 dual core application. M0 fails to start

Hello everyone,

I have an LPC4337 running uCLinux. I'm trying to get code to run in the M0 in parallell.

I load the code to 0x10080000, set the M0APPMEMMAP to 0x10080000, release the M0APP Reset and nothing happens. I have to reset the M0-core using J-link debugger to get it running.

This is my code for loading and storing the M0-code:

main()
{
 // Testing to run code in M0
 uint8_t *CM0image_start = (uint8_t *)0x10080000;

 RGU_RESET_CTRL1 = (1u << 24); // Put the M0-core in RESET

 int fd = open("m0.bin", O_RDONLY);
 if (fd)
 {
 while (read(fd, CM0image_start, 256) > 0) // Read the executable into internal SRAM area
 {
 ;
 }
 }

 unsigned int *pCREG_M0APPMAP = (unsigned int *) 0x40043404;
 *pCREG_M0APPMAP = (unsigned int) CM0image_start;
 RGU_RESET_CTRL1 = 0x0; // Release the M0 core from RESET

 while (1)
 {
 ; // Halt here, and let M0 execute.
 }
}

I can confirm that the code gets to its destination at 0x10080000.

This is my M0-code, just toggling one of my event-lines, at GPIO3[8]:

#include <stdint.h>

#define GPIO_PORT3_DIR (*((volatile uint32_t *) 0x400f600c)) #define GPIO_PORT3_TOGGLE (*((volatile uint32_t *) 0x400f630c))

void main() __attribute__ ((naked));
void main(void)
{
 GPIO_PORT3_DIR |= 0x0100; // Set 8th bit to output
 while (1)
 {
 GPIO_PORT3_TOGGLE = 0x0100; // Toggle bit 8 on GPIO3.
 }
}

My reset-vector is setup like this:

.syntax unified
.cpu cortex-m0

.thumb
.section resetvector
.word   0x10087ff0  /* stack top address */
.word   _start      /* 1 Reset */
.word   _start        /* 2 NMI */
.word   _start        /* 3 HardFault */
.word   _start        /* 4 MemManage */
.word   _start        /* 5 BusFault */
.word   _start        /* 6 UsageFault */
.word   _start        /* 7 RESERVED */
.word   _start        /* 8 RESERVED */
.word   _start        /* 9 RESERVED*/
.word   _start        /* 10 RESERVED */
.word   _start        /* 11 SVCall */
.word   _start        /* 12 Debug Monitor */
.word   _start        /* 13 RESERVED */
.word   _start        /* 14 PendSV */
.word   _start        /* 15 SysTick */
.word   _start        /* 16 External Interrupt(0) */
.word   _start        /* 17 External Interrupt(1) */
.word   _start        /* 18 External Interrupt(2) */
.word   _start        /* 19 ...   */

_start:
     bl main
     b hang

hang:   b .

And finally, my linker script:

SECTIONS
{
 . = 0x10080000;
     .text : {
 startup.o (resetvector)
 *(.text*)
 }
}

My problem is that the code execution wont start, even though I can verify that the M0-core is not in reset (by reading the RGU_RESET_ACTIVE_STATUS1 register) . The only way to start the code is to attach to the cpu using my J-Link debugger, and issuing a "reset and halt" (to step forward) or "reset and run" to run it.

If I exit my linux-app, the M0 code continues to run (if started as above), but as soon as I start my linux-app again, the execution of the M0-core stops.

If you have any pointers, please let me know.

Thanks,

Message was edited by: Bo Mellberg. Reason: formatting code sections.