Debug BLE "Softdevice"

RE: Debug BLE "Softdevice"

awneil — Thu, 08 Oct 2020 16:27:23 GMT

I don't think it's guaranteed that volatile will stop the compiler from removing an entirely useless variable?

RE: Debug BLE "Softdevice"

awneil — Thu, 08 Oct 2020 16:25:03 GMT

You need to show a complete example which illustrates the issue.

If p_local_evt is static, and is never read, then it is certainly up for optimisation.

By removing static, you make it global; so the compiler cannot know if it is referenced elsewhere or not - so cannot optimise it away.

RE: Debug BLE "Softdevice"

Kenneth — Wed, 07 Oct 2020 19:48:58 GMT

Typically if you don't want the compiler to optimize away the variable you can use volatile when declaring the variable;

https://stackoverflow.com/questions/246127/why-is-volatile-needed-in-c

Kenneth

RE: Debug BLE "Softdevice"

dilbert168 — Wed, 07 Oct 2020 15:36:55 GMT

my mistake , I meant to refer to "static variable".

In below example :

static ble_evt_t const *p_local_evt;

static void ble_evt_handler(ble_evt_t const * p_ble_evt, void * p_context)
{
// For readability.
p_local_evt = p_ble_evt;
}

The "p_local_evt" will not able to perform "Quick Watch". But it works if I removed "static".

I know this has nothing to do with Nordic or firmware.

Just wonder this is known issue in Segger as well... As I am using TI (CCStudio) has same issue.

RE: Debug BLE "Softdevice"

awneil — Wed, 07 Oct 2020 09:17:38 GMT

[quote userid="94049" url="~/f/nordic-q-a/66805/debug-ble-softdevice"]debugger cannot be used when "Stop" and "Continue" as BLE Stack is using same CPU to run. Is this still the limitation now ?[/quote]

Yes - you still need the Monitor Mode Debug.

[quote userid="94049" url="~/f/nordic-q-a/66805/debug-ble-softdevice"]the local variable cannot be added to watch[/quote]

That's not true.

However - as for any modern compiler and any IDE - you have to beware of compiler optimisation. This is a standard 'C' programming thing; not specific to Nordic or Segger - or even embedded.