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Hardfault on LPC4357 when external Ram used as heap

Posted by meowww1988 on April 12, 2016

Hi,

I am using MT48LC4M32B2P-128MBit ram on the board. It is interfaced with 32bit databus. I am able to write and read from the ram, hence I am sure the initialisation is proper.

When I use internal ram with heap4.c my code runs perfectly fine, but when I use heap5.c to use the external ram as heap, I get a hardfault. I did step by step debugging and found that whenever there is a xTaskCreate or xQueueCreate call, there is some activity in the Ram, I can see it in the memory window, I am assuming there is no problem in creation of Queues and Task. On further stepping through I found that the code goes to hard fault at the svc 0 instruction in prvStartFirstTask.

I am initialising the heap as below and then calling the function in main before any calls to RTOS functions.

static void prvInitialiseHeap( void ) { const HeapRegion_t xHeapRegions[] = {

	{(uint8_t*)0x28000000UL,0x20000},
	{ NULL, 0 }

};

vPortDefineHeapRegions( xHeapRegions );

}

Hardfault come here

__asm void prvStartFirstTask( void ) { PRESERVE8

/* Use the NVIC offset register to locate the stack. */
ldr r0, =0xE000ED08
ldr r0, [r0]
ldr r0, [r0]
/* Set the msp back to the start of the stack. */
msr msp, r0
/* Globally enable interrupts. */
cpsie i
cpsie f
dsb
isb
/* Call SVC to start the first task. */
svc 0   <--------<--------<-------<-------<--------<
nop
nop

}

Can anybody help regarding the issue? Thanks.


Hardfault on LPC4357 when external Ram used as heap

Posted by rtel on April 12, 2016

static void prvInitialiseHeap( void ) { const HeapRegion_t xHeapRegions[] = {

 {(uint8_t*)0x28000000UL,0x20000},
 { NULL, 0 }

};

If you only have one memory region then you can do this with heap4.c too - look at the configAPPLICATIONALLOCATED_HEAP configuration constant, which allows you to declare the array used as the heap yourself, and so place it where you like. HOWEVER, if you place it in external RAM, make sure you do not place it in a linker segment that means the C start up code tries to access it (to, for example, clear it to 0) before the external RAM has been configured.

/* Call SVC to start the first task. */ svc0<--------<--------<-------<-------<--------<

Normally this would be because the SVC handler was not installed in the vector table correctly, but the fact that the code runs with the heap in internal RAM discounts that possibility (assuming everything else is the same).

Two thoughts come to mind:

1) If the heap is in external RAM then the stack will be in external RAM too. Is it permitted to have the stack in external RAM with regards to speed, access cycles, etc.?

2) The SVC instruction might not be the place where the error actually occurs - but the instruction is jumping to a task and the abort happens in the task instead. Have you tried debugging the abort using the code fragment on this page: http://www.freertos.org/Debugging-Hard-Faults-On-Cortex-M-Microcontrollers.html Also, determine which task is going to run first, and place a break point at the very top of that task (before the function prologue code executes) to see if the break point is ever hit.


Hardfault on LPC4357 when external Ram used as heap

Posted by meowww1988 on April 12, 2016

I tried the first option of using heap_4.c, but getting the same results as earlier. As of now I am trying with only one task without any block statements/conditions. To confirm ram write speeds, I made a task and wrote 1MB of data as below, my tick rate is 1000Hz

~~~~ ramdata = (uint32t *)SDRAMADDR_BASE; for(;;) {

		timeFrame = xTaskGetTickCount();
		for(i=0;i<0x40000;i++)
		{
			*ramdata++=i;
		}
		timeFrame = xTaskGetTickCount() - timeFrame;	
		ramdata = (uint32_t *)SDRAM_ADDR_BASE;
		tinySprintf(txBuffer,"\r\nW %0d",timeFrame);
		printString(txBuffer);

		timeFrame = xTaskGetTickCount();
		for(i=0;i<0x40000;i++)
		{
			*ramdata++=0;
		}
		timeFrame = xTaskGetTickCount() - timeFrame;	
		ramdata = (uint32_t *)SDRAM_ADDR_BASE;
		tinySprintf(txBuffer,"\r\nO %0d",timeFrame);
		printString(txBuffer);			

}

~~~~

This gives me values of 1MB of data per 8ms if I use a uint32t pointer and 1MB of data per 30ms if I use uint8t pointer. So 125MB/s for 32 bit writes and 33MB/s for 8 bit writes. My microcontroller is running at 204MHz. Are the write speeds good enough for the requirement.

I am trying to implement your 2nd suggestion of using the hard fault exception to catch some data. Will get back with the results.


Hardfault on LPC4357 when external Ram used as heap

Posted by davedoors on April 12, 2016

Try also a breakpoint on vPortSVCHandler() in port.c. If it executes you can step from there to see where the fault comes.


Hardfault on LPC4357 when external Ram used as heap

Posted by meowww1988 on April 12, 2016

After a lot of single stepping, I think I figured where the code is actually hanging. It is hanging in this function. Although the same function was called many times during the single stepping, didn't count at what call it managed to cause a fault.

~~~~ static portFORCEINLINE void vPortRaiseBASEPRI( void ) { uint32t ulNewBASEPRI = configMAXSYSCALLINTERRUPT_PRIORITY;

__asm
{
	/* Set BASEPRI to the max syscall priority to effect a critical
	section. */
	msr basepri, ulNewBASEPRI
	dsb
	isb
}

} ~~~~

Any clues why it might be happening?


Hardfault on LPC4357 when external Ram used as heap

Posted by davedoors on April 12, 2016

Do you have the MPU turned on? Maybe you dropped out of privileged mode and fault when accessing the basepri register?


Hardfault on LPC4357 when external Ram used as heap

Posted by meowww1988 on April 12, 2016

No, I have not turned ON the MPU, by default it is Off I presume.


Hardfault on LPC4357 when external Ram used as heap

Posted by meowww1988 on April 13, 2016

I tried compiling the code given at the link. Got this code from a friend, will this work. I am not well versed in assembly.

~~~~ void HardFaultHandler(unsigned long *hardfaultargs){ volatile unsigned long stackedr0 ; volatile unsigned long stackedr1 ; volatile unsigned long stackedr2 ; volatile unsigned long stackedr3 ; volatile unsigned long stackedr12 ; volatile unsigned long stackedlr ; volatile unsigned long stackedpc ; volatile unsigned long stackedpsr ; volatile unsigned long _CFSR ; volatile unsigned long _HFSR ; volatile unsigned long _DFSR ; volatile unsigned long _AFSR ; volatile unsigned long _BFAR ; volatile unsigned long _MMAR ;

            stacked_r0 = ((unsigned long)hardfault_args[0]) ;
            stacked_r1 = ((unsigned long)hardfault_args[1]) ;
            stacked_r2 = ((unsigned long)hardfault_args[2]) ;
            stacked_r3 = ((unsigned long)hardfault_args[3]) ;
            stacked_r12 = ((unsigned long)hardfault_args[4]) ;
            stacked_lr = ((unsigned long)hardfault_args[5]) ;
            stacked_pc = ((unsigned long)hardfault_args[6]) ;
            stacked_psr = ((unsigned long)hardfault_args[7]) ;

    // Configurable Fault Status Register
    // Consists of MMSR, BFSR and UFSR
            _CFSR = (*((volatile unsigned long *)(0xE000ED28))) ;     

            // Hard Fault Status Register
            _HFSR = (*((volatile unsigned long *)(0xE000ED2C))) ;

            // Debug Fault Status Register
            _DFSR = (*((volatile unsigned long *)(0xE000ED30))) ;

            // Auxiliary Fault Status Register
            _AFSR = (*((volatile unsigned long *)(0xE000ED3C))) ;

            // Read the Fault Address Registers. These may not contain valid values.
            // Check BFARVALID/MMARVALID to see if they are valid values
            // MemManage Fault Address Register
            _MMAR = (*((volatile unsigned long *)(0xE000ED34))) ;
            // Bus Fault Address Register
            _BFAR = (*((volatile unsigned long *)(0xE000ED38))) ;

            __asm("BKPT #0\n") ; // Break into the debugger

} ~~~~


Hardfault on LPC4357 when external Ram used as heap

Posted by meowww1988 on April 18, 2016

I captured the data as required from the hard fault. My external ram is situated at 0x28000000

Captured values as below

stackedr0 = 0x28000978 stackedr1 = 0x00000000 stackedr2 = 0x00000003 stackedr3 = 0x00000000 stackedr12 = 0x00000003 stackedlr = 0x00000001 stackedpc = 0x00000000 stackedpsr = 0x00000000

CFSR = 0x00000400 HFSR = 0x40000000 DFSR = 0x00000000 AFSR = 0x00000000 BFAR = 0xE000ED38 MMAR = 0xE000ED34

Attachments

code.zip (17908642 bytes)


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