System on and keep RTC running in ultra-low power

RE: System on and keep RTC running in ultra-low power

Jørgen Holmefjord — Fri, 22 Jul 2022 12:05:31 GMT

[quote user="Countach"]In current code, I disable timer 2 and change function to app_timer_create (like ble_app_hrs example) in our agent FAE's suggestion.[/quote]

Good, TIMER will have high current consumption. RTC/app_timer is low power.

[quote user="Countach"]In current code, it costs near 3uA. It looks like to spend some time reaching 3uA.[/quote]

Yes, 3uA should be good, but I see in your video that it takes some time to reach this current. Could there be some averaging configuration of the Keysight unit that makes it take this long? I do not have any experience with this instrument myself. You should check the manual.

[quote user="Countach"]I've ordered the PPK2 in one month ago. But, the lead time is too long which needs 3 month. In current, I'm using keysight 34470A to measure it. The sample rate is 50kHz. If it's not enough, I should find another one before PPK2 arrival.[/quote]

That is unfortunate. I believe 50 kHz should be enough, the PPK2 have maximum 100kHz sampling. Please check the manual of your instrument to make sure it is not configured in some averaging mode.

RE: System on and keep RTC running in ultra-low power

Ben — Mon, 04 Jul 2022 07:48:46 GMT

[quote userid="14926" url="~/f/nordic-q-a/88774/system-on-and-keep-rtc-running-in-ultra-low-power/374961"]I do not know what is inside your timer2_init function. Is this using the TIMER peripheral, or is it an RTC timer? [/quote]

Yes, timer2_init is using TIMER 2 peripheral. The code of timer2_init is as below:

void timer2_init(void)
{
  ret_code_t err_code;
  
  nrf_drv_timer_config_t timer2_cfg;
  timer2_cfg.bit_width = NRF_TIMER_BIT_WIDTH_16;
  timer2_cfg.frequency = NRF_TIMER_FREQ_31250Hz;
  timer2_cfg.interrupt_priority = APP_IRQ_PRIORITY_LOW; // Do not set high, that will impact setting up sleep mode
  timer2_cfg.mode = NRF_TIMER_MODE_TIMER;
  
  err_code = nrf_drv_timer_init(&m_timer2, &timer2_cfg, timer2_handler);
  APP_ERROR_CHECK(err_code);
  
  nrf_drv_timer_extended_compare(
         &m_timer2, NRF_TIMER_CC_CHANNEL0, nrf_drv_timer_ms_to_ticks(&m_timer2 ,TIMER2_TICKS), 
         NRF_TIMER_SHORT_COMPARE0_CLEAR_MASK, true);
  
  nrf_drv_timer_enable(&m_timer2);
}

In current code, I disable timer 2 and change function to app_timer_create (like ble_app_hrs example) in our agent FAE's suggestion.

[quote userid="14926" url="~/f/nordic-q-a/88774/system-on-and-keep-rtc-running-in-ultra-low-power/374961"]How did you configure the pin for wakeup? Enabling sense on the pin may not generate any events unless GPIOTE PORT event is also cleared. You may have a look at this example.[/quote]

I change wakeup method with your tips and use sd_power_mode_set(NRF_POWER_MODE_LOWPWR).

It still has some problem with RTC. When I remove RTC function, it can wake up quickly.

devzone.nordicsemi.com/.../drv_5F00_calendar.c devzone.nordicsemi.com/.../08685.main.c

Yellow (Channel 1) is button pin. Press one times (Low) to enter some process, and press again to enter idle mode.

In first wake up, it should be pressed twice. But in second wake up, it should pressed few times to wake up. Please see below video.

devzone.nordicsemi.com/.../idle-mode-with-RTC.mp4

[quote userid="14926" url="~/f/nordic-q-a/88774/system-on-and-keep-rtc-running-in-ultra-low-power/374961"]Other parts of the application, like logger, PWM, etc may also contribute to the current. If you should get lowest current, you need to disable all peripherals in your application.[/quote]

In current code, it costs near 3uA. It looks like to spend some time reaching 3uA.

[quote userid="14926" url="~/f/nordic-q-a/88774/system-on-and-keep-rtc-running-in-ultra-low-power/374961"]If you start the softdevice and advertising, the current will depend on the advertising interval and/or connection interval if any connections are established. What are you using to measure the current consumption? If your equipment does not have high enough sample rate, the current may not be correctly measured. If you do not have it already, I would highly recommend you to get a PPK 2 for current measurements.[/quote]

I've ordered the PPK2 in one month ago. But, the lead time is too long which needs 3 month. In current, I'm using keysight 34470A to measure it. The sample rate is 50kHz. If it's not enough, I should find another one before PPK2 arrival.

Thank you.

RE: System on and keep RTC running in ultra-low power

Jørgen Holmefjord — Thu, 30 Jun 2022 15:46:28 GMT

[quote user="Countach"]Before this, I don't run timer2_init() function (means comment timer2_init()), sleep current can be near 1uA. When I remove comment on timer2_init() (means run timer2_init()), and I disable and run un-initial timer2 before sleep. It's measured about 45uA. How do I close it?[/quote]

I do not know what is inside your timer2_init function. Is this using the TIMER peripheral, or is it an RTC timer?

[quote user="Countach"]2. Base on above code, I can't wake up SoC after entering system on mode. In previous wake up code, it works in system off. Instead of sd_power_system_off() to using WFE and WFI, it is ARM low-power standby mode. It should be triggered by events for waking up. But, it looks like not working in my GPIO wake up pin.[/quote]

How did you configure the pin for wakeup? Enabling sense on the pin may not generate any events unless GPIOTE PORT event is also cleared. You may have a look at this example.

[quote user="Countach"]3. Enable comments at Question 3 block (RTC) and comment timer2_init() in above code. The current measured 11uA. It is not near 1.9 uA. [/quote]

Other parts of the application, like logger, PWM, etc may also contribute to the current. If you should get lowest current, you need to disable all peripherals in your application.

[quote user="Countach"]4. Reserve RTC function (Question 3) and enable Question 4, and I don't enable advertising in this part. It has 820uA. Which function should be disabled?[/quote]

If you start the softdevice and advertising, the current will depend on the advertising interval and/or connection interval if any connections are established. What are you using to measure the current consumption? If your equipment does not have high enough sample rate, the current may not be correctly measured. If you do not have it already, I would highly recommend you to get a PPK 2 for current measurements.

RE: System on and keep RTC running in ultra-low power

Ben — Fri, 10 Jun 2022 12:04:56 GMT

Hi Jørgen,

I try to disable peripheral function. Power saving is under 1mA. But, it's still too high. I try to separate some code to check sleep current. Therefore, I still have few questions.

1. I comment BLE initial function code as below:

Before this, I don't run timer2_init() function (means comment timer2_init()), sleep current can be near 1uA. When I remove comment on timer2_init() (means run timer2_init()), and I disable and run un-initial timer2 before sleep. It's measured about 45uA. How do I close it?

//uart_init();
  log_init();

  timers_init();

  drv_gpio_configuration();
  
  pwm_init();
  
  saadc_sampling_event_init();
  saadc_init();
  timer2_init();      // Question 1
  
  /* Question 3
  sync_rtc(22, 6, 8, 20, 02, 55);
  lfclk_config();
  rtc_config();*/
  
  power_management_init();
  /* Question 4 comment for checking peripheral sleep current
  ble_stack_init();
  gap_params_init();
  gatt_init();
  services_init();
  advertising_init();
  conn_params_init();*/

2. Base on above code, I can't wake up SoC after entering system on mode. In previous wake up code, it works in system off. Instead of sd_power_system_off() to using WFE and WFI, it is ARM low-power standby mode. It should be triggered by events for waking up. But, it looks like not working in my GPIO wake up pin.

3. Enable comments at Question 3 block (RTC) and comment timer2_init() in above code. The current measured 11uA. It is not near 1.9 uA.

4. Reserve RTC function (Question 3) and enable Question 4, and I don't enable advertising in this part. It has 820uA. Which function should be disabled?

Please assistance me to solve it.

Thank you.

RE: System on and keep RTC running in ultra-low power

Jørgen Holmefjord — Thu, 09 Jun 2022 13:22:06 GMT

Hi,

It is possible to run the RTC in System ON mode, but not in System OFF. The expected current consumption is given by I_{ON_RAMOFF_RTC} in Current consumption: Ultra-low power, but note that any additional running peripheral will increase the current consumption, as entering System ON mode will not automatically power down peripherals.

If you are measuring 2.x mA current, some additional peripherals must be running. The usual suspects at this current-level is for instance UARTE in receive mode, or the SAADC peripheral.

Best regards,
Jørgen