Sleep until WDT timesout

RE: Sleep until WDT timesout

rshankle — Thu, 01 Aug 2019 11:38:48 GMT

thanks for all the help.

I appreciate it.

Bob

RE: Sleep until WDT timesout

Susheel Nuguru — Thu, 01 Aug 2019 08:12:26 GMT

Then systemoff will not suit you. That is, you won't be able to go to deepest sleep mode if any external sensor/input is not involved.

RTC is your good bet, it will run on LFCLK and the example you can see in SDK15.3\examples\peripheral\rtc\main.c

RE: Sleep until WDT timesout

rshankle — Wed, 31 Jul 2019 13:35:29 GMT

We don't have the luxury of having something external running to wake up the nRF52832 device. We need the device to wake itself up.

RE: Sleep until WDT timesout

Susheel Nuguru — Wed, 31 Jul 2019 13:30:33 GMT

[quote user="rshankle"]The device is a remote sensor and just needs to wake up read some IO, phone home, shut everything off and go back to sleep. Maintaining connectivity with other devices isn't needed.[/quote]

Then SystemOFF (deepest sleep mode) seems to suit your needs. You just need a proper wakeup mechanism configured with one GPIO pin, which could be an interrupt line from the externally powered sensor.

RE: Sleep until WDT timesout

rshankle — Wed, 31 Jul 2019 13:23:29 GMT

I'm looking for ideas. What is the deepest sleep and still have the device wake itself up. The device is a remote sensor and just needs to wake up read some IO, phone home, shut everything off and go back to sleep. Maintaining connectivity with other devices isn't needed.

The device does write to NVRAM before going to sleep so it can read that data on the next wakeup cycle.

There is an external 32Khz crystal connected if that helps minimize power.

(Under 20uA would probably be a solution.)

thanks,

Bob

RE: Sleep until WDT timesout

Susheel Nuguru — Wed, 31 Jul 2019 13:08:51 GMT

Bob,

Waking up from system off mode is different than WFE. How are you intending to wake the chip from SystemOFF?
What is the acceptable power consumption in sleep mode you are aiming for?
Being in deep sleep will make your devices lose connection with each other

[quote user="rshankle"]What is the deepest sleep mode I can put the nrf52832 into and leverage this crystal? Goal being to wake up after a given time period (in seconds to minutes.)[/quote]

The timers in the chip will be off, so you cannot reply on-chip timers to wake the chip here. Please read carefully the four ways that can wake the chip from system off mode.

RE: Sleep until WDT timesout

rshankle — Mon, 29 Jul 2019 17:16:45 GMT

Hi Susheel,

I wanted to rule out that my hardware is drawing the high current, so I created a software build that just has:

#define RAM_RETENTION_OFF       (0x00000003UL)  /**< The flag used to turn off RAM retention on nRF52. */

int main( void )
{
#ifdef NRF51
    NRF_POWER->RAMON |= (POWER_RAMON_OFFRAM0_RAM0Off << POWER_RAMON_OFFRAM0_Pos) |
                        (POWER_RAMON_OFFRAM1_RAM1Off << POWER_RAMON_OFFRAM1_Pos);
#endif //NRF51
#ifdef NRF52
    NRF_POWER->RAM[0].POWER = RAM_RETENTION_OFF;
    NRF_POWER->RAM[1].POWER = RAM_RETENTION_OFF;
    NRF_POWER->RAM[2].POWER = RAM_RETENTION_OFF;
    NRF_POWER->RAM[3].POWER = RAM_RETENTION_OFF;
    NRF_POWER->RAM[4].POWER = RAM_RETENTION_OFF;
    NRF_POWER->RAM[5].POWER = RAM_RETENTION_OFF;
    NRF_POWER->RAM[6].POWER = RAM_RETENTION_OFF;
    NRF_POWER->RAM[7].POWER = RAM_RETENTION_OFF;
#endif //NRF52

    // Set nRF5 into System OFF. Reading out value and looping after setting the register
    // to guarantee System OFF in nRF52.
    NRF_POWER->SYSTEMOFF = 0x1;
    (void) NRF_POWER->SYSTEMOFF;
    while (true);
}

The current draw in this mode is 12uA.

So I know I'm close just missing a setting somewhere.

thanks,

Bob

(ps I couldn't get the insert code feature to make the window larger above, if you click on it there is more.)

RE: Sleep until WDT timesout

rshankle — Mon, 29 Jul 2019 14:50:45 GMT

Hi Susheel,

My board has an external 32KHz crystal. What is the deepest sleep mode I can put the nrf52832 into and leverage this crystal? Goal being to wake up after a given time period (in seconds to minutes.)

Thanks much for any pointers. I have a multi-meter on my board measuring current and I can't get it to stay below 170uA in sleep mode. (I think I'm missing a power down mode of some sort.)

thanks,

Bob

RE: Sleep until WDT timesout

Susheel Nuguru — Wed, 24 Jul 2019 07:16:11 GMT

You can use an RTC to wake the system up from WFE sleep, the watchdog timeout inserts an unnecessary reset in between, which if I understood correctly is something you could avoid. Look at the example provided at nRF5_SDK_15.3.0_59ac345\examples\peripheral\rtc\main.c

RE: Sleep until WDT timesout

Otso Jousimaa — Tue, 23 Jul 2019 15:22:47 GMT

Hello,

Someone from Nordic can point you to their official examples, here's how I did it at Ruuvi:

https://blog.ruuvi.com/ruuvi-firmware-part-11-scheduler-c95836f3105c

That blog is a part of lot larger series and quite heavy to grasp it on its own.

In essence the timer interrupt adds call to data update function to Nordic scheduler, and the timer interrupt brings the tag out of the sleep.

First thing once tag is out of the sleep is to execute scheduled function, including data update scheduled above.

After scheduler has run the main loop calls yield() which in turn will call the Nordic power management function. In your case I'd add calls to switch off the mofsets in yield and switch on once the tag has exited Nordic power management.

You don't necessarily need to use the scheduler, just having timer interrupt is enough to bring tag out of the sleep. However I'd prefer to not run the sensor reads in timer interrupt context, as it could mask other interrupts such as SPI data ready and lock your program.

RE: Sleep until WDT timesout

rshankle — Tue, 23 Jul 2019 15:09:27 GMT

Ok, so I'm working on adding nrf_pwr_mgmt_run() to my project, which obviously needs nrf_pwr_mgmt.h, when I start compiling it starts complaining about wanting nrf_section_iter.... so I add that. The latest complain is it wants __start_pwr_mgmt_data and __stop_pwr_mgmt_data defined. (Digging into that I find I need sections_placement.xml file updated, but I only see flash_placement.xml file.)

So before I tunnel down this rabbit hole any further. Is there a simple example that just puts the device in the lowest power mode (with some internal timer or WDT that will bring it out of sleep mode after a set period. External input is not an option.)

Thanks much!
Bob

FYI my current setup puts the device in sleep mode drawing 210uAmps (When the device is awake it draws about 8mAmps.)

RE: Sleep until WDT timesout

rshankle — Tue, 23 Jul 2019 11:44:12 GMT

Hi Otso,

Thanks for the response, we have mosfets that turn on/off the sensors so I'm not thinking the problem is sensors draining batteries.

Can you point to an example using nrf_pwr_mgmt_run() with timer triggering it?

thanks again!
Bob

RE: Sleep until WDT timesout

Otso Jousimaa — Mon, 22 Jul 2019 21:45:05 GMT

Hello,

First thing I'd check is if the external sensors are in low-power mode during sleep, if some sensor stays in measuring mode it can drain your battery regardless of what your device does.

Second, I'd use `nrf_pwr_mgmt_run();` instead of direct call to `__WFE();`

Third, nRF52 can spend relatively long time in active mode during boot, I'd rather use timer interrupt to wake up from sleep and let watchdog handle only the cases where program has hanged.