We have two xtimer-like RTC-based timers implemented on STM32L1:
* https://github.com/unwireddevices/RIOT/tree/loralan-public/sys/rtctimers — rtctimers for ~1 second to 1 week delays, it uses regular RTC calendar
* https://github.com/unwireddevices/RIOT/tree/loralan-public/sys/rtctimers-millis — rtctimers-millis for ~1 ms to 1 min delays, it uses RTC_SSR subseconds register (not available on some devices) and RTC calendar seconds register
* RTC_SSR driver implementation — https://github.com/unwireddevices/RIOT/blob/loralan-public/cpu/stm32l1/periph/rtc.c
P.S. On STM32L1, regular XTIMER can not run from 32 kHz clock in stop or standby mode, as all TIMx timers need APB1 clocking. Switching xtimer to RTC clock will degrade its resolution.
--
Sincerely yours,
Oleg Artamonov
+7 (916) 631-34-90
21.11.2017, 19:27, "Daniel Evans" <photonthun...@gmail.com>:
,First, I should add that I currently have a working samd21 low power implementation but to accomplish that I use rtt.c for my always running clock and then standby sleep the module whenever it gets to the idle task. This is a hack and is not a clean implementation and means you don’t use XTIMER and no use of the nice built in protocols, I have my own hacked LoRa mesh network.Referring specifically to the samd21, which includes the samr21 and loosely the saml21, this is the path as I see it for getting low power working natively with RIOT:1) Add a method to make setting up the generic clocks that includes run in standby and on demand options.2) Add flags for peripherals so that you can set the clock and run in standby3) Tweak XTIMER so that it can be run by a low power 32kHz clock when sleepingAll of these things have been discussed and are in the works and are on the list but not currently top priority. Low power is critical for my application and I am a little surprised it isn’t for more users, but I imagine others just hack around it as well?Hope that helps a little,DanOn Nov 21, 2017, at 6:07 AM, Francisco Molina <francisco.mol...@inria.cl> wrote:_______________________________________________
>Issues #7743 and #7332 both discuss the problem.
>
>DanI saw those issues but they only refer to the fact that xtimer doesn't run during sleep modes, is that the only issue? CheersFrancisco
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