CC1352R: How to Save Task Call Stacks to Debug Watchdog

I have noted that some links to old E2E threads is not working. It looks like an extra number has been added to the address. Could it be this thread: https://e2e.ti.com/support/wireless-connectivity/bluetooth-group/bluetooth/f/bluetooth-forum/543079/cc2640-write-to-the-flash-from-hwi-thread that you are looking for? Generally it could be difficult to store data since you risk that the watchdog reset is executed before you manage to store data since the flash access is time consuming.

Could you describe your setup for keeping the watchdog alive and (ideally) not time out? Which other output methods do you have on the production units, do you have LEDs, UART, SPI?

Yeah, that looks like the correct thread! Thank you.
Based on Aslak N.'s post from that conversation, the stack pointer (SP) for each Task_Object is stored in the context variable. What about the program counter (PC)? How can I determine the PC value for each task?

I want to save the PC, SP, and LR registers for each task so that I can load them into CCS as described in Decoding An Exception Dump in CCS Using The Register View: e2e.ti.com/.../faq-how-do-i-trace-backward-to-the-code-that-caused-an-exception-in-my-ti-rtos-app 

I already have code set up to write log messages to the external flash when the watchdog fires. I just need to know where to get the PC, SP, and LR registers for each task so I can figure out where the program is getting hung up.

Thank you!
Peter

I will let a SW expert to follow up on this one. 

Hi Peter,

I don't think there is any variable for SP stored for the task. Here is the TI-RTOS7 definition of the Task struct in Task.h:

struct Task_Struct {
    Queue_Elem qElem;
    Queue_Elem objElem;
    char * name;
    volatile int priority;
    unsigned int mask;
    void * context;
    Task_Mode mode;
    Task_PendElem *pendElem;
    size_t stackSize;
    char *stack;
    IHeap_Handle stackHeap;
    Task_FuncPtr fxn;
    uintptr_t arg0;
    uintptr_t arg1;
    void * env;
    void * *hookEnv;
    bool vitalTaskFlag;
    Queue_Handle readyQ;
    uint32_t checkValue;
    void * tls;
};

Cheers,

Marie H

How does the ROV show a backtrace for each task? It must read the state of each task from RAM, correct?

Whatever information the ROV uses to produce these program counter (PC) values for each task, that's what I want to save. Please tell me where this information is stored.

Thank you,
Peter

Hello,

I will escalate this to the ROV experts for more insight. I will pass on any updates as I receive them

Thanks

ki

I am still waiting for feedback. Thank you for your patience.

I have gotten some more details from engineering.

Peter Crowley said:

How does the ROV show a backtrace for each task? It must read the state of each task from RAM, correct?

Your assumption is correct in that the data is being read from RAM.

The SP pointer is stored in the Task_stat data structure. 

It may not be so simple to walk the stack to construct a function call

More details should be documented in the TI-RTOS user's guide

Hope this helps

ki