How to access memory registers

Hello Sravan,

CPU registers are intrinsic to the CPU and cannot be read to a memory, You would need to use instructions to Push them into a memory e.g. on a Fault condition by using PUSH to stack.

Regards
Amit

Hi Amit,

Ok. How can I push it to stack ??
Is it possible by writing a c code?

Regards
Sravan

Hi Amit,

Ok got it. I want to know whether is there any way to access without assembly code.
Thank you


Regards
Sravan

Hello Sravan

C code will not do Push of all the registers

Regards
Amit

Hi Amit,

Actually I don't know how to use assembly in c.
I just know asm(""); instruction , I can use MOV or LDR or PUSH to read registers. But after that how can I assign it to variables (int ..etc)

Where can I get information about using assmebly in c for TIVA microcontrollers


Thanks
Regards

Hi Amit,

Thank you now I am able to read pc and lr values .

Regards
Sravan

Hello Sravan,

Do post back the final code, it would be of tremendous use for other members

Regards
Amit

Hi Amit,

www.freertos.org/Debugging-Hard-Faults-On-Cortex-M-Microcontrollers.html

The same code I am using which was mentioned in the above link

Regards
Sravan

Hello Sravan,

Thank you.

Regards
Amit

Hi Amit,

Please find the code snippet

int lr;
__asm(" str r14, [r13, #4] ");
sprintf(word,"LR = %x",lr);

/* Display Link Register*/
for(lr = 0; word[lr] != '\0' ;lr++)
UARTCharPut(UART0_BASE,word[lr]);
__asm(" mrs r4,psp \n");
__asm(" str r4, [sp, #4] \n");

/* Next line*/
UARTCharPut(UART0_BASE,'\n');
UARTCharPut(UART0_BASE,'\r');

/* Display PSP*/
memcpy(registerMap,(unsigned int *)lr,100);

sprintf(word,"PSP--dump R0= %x R1= %x R2= %x R3 = %x R12= %xLR= %x PC =%x", \
registerMap[0],registerMap[1],registerMap[2], \
registerMap[3],registerMap[4],registerMap[5],registerMap[6]);
for(lr = 0; word[lr] != '\0' ;lr++)
UARTCharPut(UART0_BASE,word[lr]);

/* Display MSP*/
UARTCharPut(UART0_BASE,'\n');
UARTCharPut(UART0_BASE,'\r');
__asm(" mrs r4,msp \n");
__asm(" str r4, [sp, #4] \n");
memcpy(registerMap,(unsigned int *)lr,100);


sprintf(word,"MSP--dump R0= %x R1= %x R2= %x R3 = %x R12= %xLR= %x PC =%x", \
registerMap[0],registerMap[1],registerMap[2], \
registerMap[3],registerMap[4],registerMap[5],registerMap[6]);
for(lr = 0; word[lr] != '\0' ;lr++)
UARTCharPut(UART0_BASE,word[lr]);

UARTCharPut(UART0_BASE,'\n');
UARTCharPut(UART0_BASE,'\r');

As of now I am copying it to lr(c variable) through stack pointer which is r13. I am getting expected values.

I am curious to know that is there any other way.
If I want to take all sram dump this goes in messy way that why, is there any alternative way??


Regards
Sravan

Hello Sravan

The CPU register dump is critical when there is a bus fault or device OS crash and it can be used to provide debug information
Other than that I would not recommend it as part of a regular debug (JTAG exempted)

Regards
Amit

Hi Amit,

Actually I am using TM4C129DNCPDT MCU and TI-RTOS .
My MCU is crashing when I kept it idle and because of watchdog it is rebooting and it is not consistent.
If I am about to debug it is not happening and if I make huge changes in my code then this issue I am unable to reproduce.

I suspect on the interrupt handling, hence I want to take the psp,lr value when it got fault exceptions.
That's why I want to take the dump , so it is only way for me to find the cause of this exception.

Regards
Sravan

Hello Sravan

Instrumentation for crash handling must be there in TI-RTOS. May be send a post on the TI-RTOS forum for the easier way out.

Regards
Amit