How to use hardfault exception library ?

RE: How to use hardfault exception library ?

Vidar Berg — Wed, 27 Jun 2018 08:22:51 GMT

Unfortunately, it is going to require changes to the interrupt forwarding implementation inside the softdevice. However, this problem only seems to occur when some specific condition(s) are met, I haven't experienced it before I tried hardfault_genhf_invalid_fp() that branches to address 0. So the fault exception should be forwarded to the application in most cases.

RE: How to use hardfault exception library ?

dlip — Tue, 26 Jun 2018 21:11:51 GMT

Is there a workaround for this that will allow the application to process hardfaults?

RE: How to use hardfault exception library ?

Vidar Berg — Wed, 20 Jun 2018 08:28:29 GMT

Hi,

I've replicated the behavior you saw with hardfault_genhf_invalid_fp(). The softdevice should forward hardfault exceptions to the application, which it's not working in this particular case. The forwarding mechanism triggers another hardfault inside the fault handler that leads to a CPU lockup reset. This has been reported as a bug internally. Note that lockup reset is disabled while the device is in debug interface mode, that is why the program hangs inside the softdevice when you try to debug it (lockup reset).

"Also, how did you know the program is stuck in soft device's handle"

It was based on the CPU registers from your screenshot:

Here's the example I used for test:

devzone.nordicsemi.com/.../ble_5F00_app_5F00_hrs_5F00_hf_5F00_test.zip

RE: How to use hardfault exception library ?

Salman Azmat — Wed, 20 Jun 2018 05:19:17 GMT

Hi,

I'm using hardfault_genhf_invalid_fp() function to generate the hardfault as shown in the picture in my previous comment. Also, how did you know the program is stuck in soft device's handler ? Also, I'm generating the fault before initializing the ble_stack and other modules.

RE: How to use hardfault exception library ?

Vidar Berg — Thu, 14 Jun 2018 07:03:30 GMT

Hi,

Did you write to address 0x80000000 to trigger this hardfault? Your screenshot shows the program being stuck in the softdevice's hardfault handler. This may happen if the app returns from app_error_fault_handler() after a softdevice assert.

RE: How to use hardfault exception library ?

Salman Azmat — Wed, 13 Jun 2018 10:44:37 GMT

Hi, I tried disbaling all the V7M breakpoints, but still it doesn't work.

RE: How to use hardfault exception library ?

Vidar Berg — Wed, 13 Jun 2018 07:39:56 GMT

Segger Embedded studio halts the CPU when a fault exception occurs (shown as "vector catch" in console window). Maybe that is why the program is not reaching the hardfault handler in your application. You can disable vector catch for hardfault in the breakpoint view (press ctrl + alt + b to open)

RE: How to use hardfault exception library ?

Salman Azmat — Wed, 13 Jun 2018 06:18:03 GMT

Hi, I included the gcc file as I'm using seggers embedded studio. But still the handlers don't get invoked. Currently my project path contains hardfault_handler_gcc.c and hardfault_implmenetation.c files, and I did "#include "hardfault.h"" in my main.c.

Though, I was able to generate hardfaults with "hardfault_genhf_invalid_fp()" function after doing #include "hardfault_genhf.h". But still no luck with the handler.

RE: How to use hardfault exception library ?

Vidar Berg — Mon, 11 Jun 2018 13:05:04 GMT

Hi,

hardfault_handler_<toolchain>.c needs to be included in order for HardFault_c_handler() to be invoked on a fault exception. Did you include one of the handler files from \components\libraries\hardfault\nrf52\handler (different versions depending on toolchain)?

RE: How to use hardfault exception library ?

Salman Azmat — Mon, 11 Jun 2018 12:33:03 GMT

Also, according to following link, a hardfault_handler is called upon the fault, which has a while(forever), and we can modify it to reset the chip or get the stack pointer, where is this handler implemented(in some .c file, I don't think I'll be able to modify the .s file) ?

devzone.nordicsemi.com/.../an-introduction-to-error-handling-in-nrf5-projects