[riot-devel] How to properly use cortexm_sleep

Robert Hartung hartung at ibr.cs.tu-bs.de
Wed May 29 13:02:52 CEST 2019


Hey everyone,

let me say a few words as Kaspar and I have been driving the
implementation of this. In general there is no need to manually go to
sleep, as the deepest sleep mode will always be selected from the idle
thread depending on the deepest mode possible.
Which mode is possible depends on the used periphs. For STM32 sleep was
long not possible, as PM_BLOCKER_INITIAL was initialized with 1 for each
mode, which resulted in never going to a sleep mode.
>From what I can see is that it is still initialized with ones?
Nevertheless, to make us of it PM_BLOCKER_INITIAL should be initialized
with 0. All periph modules should then individually block the sleep
modes they can not operate in. For now the biggest problem was the
shell/uart, as it would always block any sleep modes.
An exception are some platforms, as they have a Uart which can wake them
up from sleep modes.

I have modified the atmega1284p implementation to make use of it [0] and
[1].

Best Regards
Robert

[0]
https://github.com/ibr-cm/RIOT/blob/idealvolting-rc1/cpu/atmega1284p/periph/pm.c
[1]
https://github.com/ibr-cm/RIOT/blob/idealvolting-rc1/cpu/atmega_common/periph/

On 28.05.19 20:01, Kees Bakker wrote:
> Nice,
> 
> Thanks for sharing
> 
> On 28-05-19 08:48, Oleg Artamonov wrote:
>> Hi.
>>
>> Yes, but for emergency reboots only.
>>  
>> Implementations:
>> https://github.com/unwireddevices/RIOT/blob/loralan-public/cpu/stm32_common/periph/iwdg.c
>> and
>> https://github.com/unwireddevices/RIOT/blob/loralan-public/cpu/nrf5x_common/periph/iwdg.c
>>  
>> For task scheduling on sleepy devices we use RTC-based timers with 1
>> ms resolution and 1 week max period
>> (https://github.com/unwireddevices/RIOT/tree/loralan-public/sys/rtctimers-millis;
>> on STM32L, we use regular HW RTC with SSR register, on nRF52 —
>> "software" RTC implemented on top of HW RTT unit).
>>  
>> -- 
>> /Sincerely yours,/
>> /Oleg Artamonov/
>> /+7 (916) 631-34-90/
>> /www.unwds.com/ <http://www.unwireddevices.com>
>>  
>>  
>>  
>> 27.05.2019, 21:57, "Kees Bakker" <kees at sodaq.com>:
>>
>>     Hey Oleg,
>>
>>     Are you using the watchdog?
>>      
>>     On 27-05-19 07:30, Oleg Artamonov wrote:
>>
>>         Hi
>>          
>>         We do. On STM32L0, STM32L1, nRF52, etc.
>>          
>>         Checking for interrupt flags is absolutely useless here - 1)
>>         WFI checks for any relevant interrupt flags, 2) interrupt
>>         still can happen between check and WFI.
>>          
>>         -- 
>>         /Sincerely yours,/
>>         /Oleg Artamonov/
>>         /+7 (916) 631-34-90/
>>         /www.unwds.com/ <http://www.unwireddevices.com/>
>>          
>>          
>>          
>>         26.05.2019, 18:40, "Kees Bakker" <kees at sodaq.com>
>>         <mailto:kees at sodaq.com>:
>>
>>             Hey
>>
>>             Is there anyone using cortexm_sleep for a real
>>             application? And if
>>             yes, would you want to share how exactly that's done?
>>
>>             Let me say that I've never written a real application with
>>             RIOT, but
>>             I would like to. One of the important requirements is that
>>             the app
>>             must be in sleep (deep sleep) and only wake up to do some
>>             work.
>>             And another requirement is to use the watchdog.
>>
>>             That said, I'm familiar with the following Arduino pseudo
>>             code.
>>
>>                  while (forever) {
>>                      do stuff
>>
>>                      disable interrupts
>>                      if !certain condition
>>                          __WFI();
>>                      enable interrupts
>>                  }
>>
>>             That "certain condition" is mostly checking that no WDT or
>>             RTC interrupt
>>             occurred before disabling the interrupts. These interrupts
>>             are handled
>>             by ISR's and they set a flag. This is a fairly common
>>             thing to do, I think.
>>
>>             I don't see (or understand) how this can be achieved with
>>             RIOT-OS and
>>             cortexm_sleep. It is essential to check the condition
>>             AFTER disabling the
>>             interrupts.
>>
>>             --
>>             Kees Bakker
>>             _______________________________________________
>>             devel mailing list
>>             devel at riot-os.org <mailto:devel at riot-os.org>
>>             https://lists.riot-os.org/mailman/listinfo/devel
>>
>>          
>>
>>         _______________________________________________
>>         devel mailing list
>>         devel at riot-os.org <mailto:devel at riot-os.org>
>>         https://lists.riot-os.org/mailman/listinfo/devel
>>
>>     ,
>>
>>     _______________________________________________
>>     devel mailing list
>>     devel at riot-os.org <mailto:devel at riot-os.org>
>>     https://lists.riot-os.org/mailman/listinfo/devel
>>
>>
>> _______________________________________________
>> devel mailing list
>> devel at riot-os.org
>> https://lists.riot-os.org/mailman/listinfo/devel
> 
> 
> _______________________________________________
> devel mailing list
> devel at riot-os.org
> https://lists.riot-os.org/mailman/listinfo/devel
> 

-- 
Robert Hartung, M.Sc.

Technische Universität Braunschweig
Institut für Betriebssysteme und Rechnerverbund
Mühlenpfordtstr. 23, Raum 115
38106 Braunschweig

Fon: +49 (531) 391 - 3264
Fax: +49 (531) 391 - 5936
E-Mail: hartung at ibr.cs.tu-bs.de


More information about the devel mailing list