nRF51822: adjust Bootloader space

RE: nRF51822: adjust Bootloader space

Amanda Hsieh — Fri, 20 May 2022 09:08:30 GMT

Hi,

The bootloader handles this scenario(starting from SDK v15/v16). It will check if the WDT is already running or not, and feed all channels that are enabled. But if you are using an older SDK version, you need to backport this feature yourself. You can take a look at nrf_bootloader_wdt.c from the newest SDK version to see how you should do this.

-Amanda

RE: nRF51822: adjust Bootloader space

bojan — Thu, 19 May 2022 13:07:57 GMT

I can try to initialize watchdog from Bootloader but what will happen in the case it is already initialized from the main Application?

It can be that WDT channel 0 will be used in the main application and WDT channel 1 in the Bootloader. If I feed channel 1 instead of channel 0 from the Bootloader, that might restart the CPU. What do you think?

RE: nRF51822: adjust Bootloader space

Amanda Hsieh — Thu, 19 May 2022 13:03:44 GMT

Hi,

nrf_drv_wdt_channel_feed is used to feed the invidual watchdog channel.

Could you try to initialize the Watchdog timer with nrf_drv_wdt_init?

-Amanda

RE: nRF51822: adjust Bootloader space

bojan — Thu, 19 May 2022 12:52:05 GMT

Hello, Amanda Hsieh.

Thanks for the reply. It seems it is working fine.

One more question... I don't initialize the Watchdog timer within the Bootloader, I just feed it periodically with

nrf_drv_wdt_channel_feed(0);

This is basically writing a 0x6E524635UL magic number into NRF_WDT->RR[0] register. Do you see any issue with that in the case our main Application does not use (initialize) Watchdog timer?

Regards,

Bojan.

RE: nRF51822: adjust Bootloader space

Amanda Hsieh — Thu, 19 May 2022 11:07:53 GMT

Hi,

[quote user=""]Is it safe that we increase the Bootloader area for ~2KB and take this space from the Application area (so that now we have 127-2 = 125KB for the Application code)?[/quote]

Yes, as long as the rest space is enough for your application.

The modification looks fine. Can it work without issue?

Regards,
Amanda