OTA DFU hardware resources

[JohnBrown]

I have a strange problem trying to use timer1 in a trivial app that's loaded via DFU. I can't get delays longer than about 1 second, despite having the prescaler set to 9. So I am wondering if the DFU initialization has changed some register associated with timer1.

Also, I would like to modify the DFU code such that the LED flashes, instead of being on solidly, and I wondered if I can use a timer and PPI channel to do this without screwing the bootloader.

[JohnBrown]

OK, answering part 1 of my question, I hadn't realised that only timer0 has the 32 bit capability.

Still like to know if I can use a timer and PPI to flash the LED for DFU, though.

[Wojtek]

Why don't you just use app_timer which is implemented on RTC? It is perfect for longer (i use it to generate events from 3ms up to few minutes) delays...

[JohnBrown]

Because I'm doing this prior to starting the soft device. Anyway, as I said above, I found the problem.

[Stefan Birnir Sverrisson]

Hi JohnBrown

I dont think the bootloader uses any PPI channels or TIMER peripherals. There are only limitations of the softdevice that apply. The softdevice blocks TIMER0 but the other timers should be available. Take a look in the softdevice specification (SDS) for the softdevice you are using to find out what PPI channels are occupied by the softdevice. You should anyhow be free to use all TIMERs and PPI channels before enabling the softdevice.

[JohnBrown]

Thanks, Stefan. I had looked at the soft device spec., but wasn't sure if the DFU code used any extra hardware resources. I tried it anyway, and it seems to work fine.