esb with softdevice - clock initialization failes (urgent)

[Michal]

Hi,

For my application I was using ESB without softdevice and just recently I wanted to add dfu so I had to add softdevice as well.

After adding softdevice I found out that my piece of code that is starting lfclk and hfclk is now failing.

void clocks_start( void )
{
    nrfx_clock_enable();

    nrfx_clock_hfclk_start();
    while (!nrfx_clock_hfclk_is_running())
                 ;

    nrfx_clock_lfclk_start();
    while (!nrfx_clock_lfclk_is_running())
                 ;
}

First symptom is that hfclk_is_running function never returns true. After commenting out that while() loop when application reach lfclk_start it simply stops execution - I think it gets stuck somewhere in softdevice.

I already tried to use softdevice api for requesting clocks and added softdevice enabling, but then I got some other weird errors - probably softdevice was clashing with ESB, but didn't invetigate it much further. Then I read somewhere that if application does not use softdevice - like in my case - I can just ignore it. But then the question is why this clock function is failing?

Hoping for a quick answer !

Michał

[ovrebekk]

Hi Michał

When using the SoftDevice you shouldn't access the clock peripheral directly, which is what the nrfx_clock driver is doing. 

Starting LF clock is not necessary, since the SoftDevice starts this automatically, but if you want to change the LF clock source you have to do this as a part of the SoftDevice initialization. 

Starting the external HF clock can be done by calling sd_clock_hfclk_request(), after you have enabled the SoftDevice. 

Best regards
Torbjørn 

[Michal]

Hi Torbjørn,

I am a bit confused: I don't want to use softdevice in my main application so I am not enabling softdevice at all. Shouldn't in that case  "standard" nrfx_clock api be fine as suggested by Nguyen? I tried that but it doesn't work for me.

I tried to add softdevice to my application by using softdevice handler module, because I also need flash access. Then I am only requesting hfclk and that works fine. Unfortunately when initializing ESB protocol, exactly when accesing first RADIO register (which is TXPOWER but I don't this matters) application hangs. Is using ESB with softdevice enabled a valid use case? I guess all RADIO registers should be accessed via SD api when it is enabled but there no such ESB implementation which uses SD api.

Best regards

[ovrebekk]

Hi Michał

I assume you are using sleep modes occasionally?

If so, which ones?

Any chance you are disabling RAM retention in sleep to reduce current draw? 

Michal said:

0x00000A60  is not mysterious anymore it is MBR's hardfault handler function address right?

That is correct, but this should forward to the hardfault handler or app_error_handler of the application. Will the code execution not continue after reaching 0x00000A60?

Best regards
Torbjørn 

[Michal]

Hi Torbjørn,

I am calling __WFE() in main loop but the code seems to enter hardfault even if I remove that. Also I don't configure RAM retention in my application, I don't know if it is enabled by default?

Code goes to A60 and then enters Hardfault from ses_startup_nrf52840.s.

Best regards,
Michał

[Krzysztof Chruscinski]

Could it be some stack size? As now interrupt goes through mbr and softdevice a bit more stack is needed.

[Michal]

Hi,

Turns out I changed something in nrf_esb.c when testing in the beginning and that change only affected RX part. After reverting all changes in nrf_esb.c everything works smooth. So after all looks like only change I needed was to make an offset in linker for those 8 bytes used by softdevice.

Thank you all for the support!

Best regards,
Michał

[ovrebekk]

That is excellent news Michał, I will close the case then