Enter in SYSTEM ON doest not work

RE: Enter in SYSTEM ON doest not work

Louis Hatte — Tue, 23 Jul 2019 09:36:02 GMT

Hi Simon

Your post resolved my issue. I have now 6µA consumption in SYSTEM ON mode on my main project.

Thanks for your help!

RE: Enter in SYSTEM ON doest not work

Simonr — Mon, 22 Jul 2019 06:24:41 GMT

Are you struggling to disable the UART properly, because you won't be able to transmit over UART and keep a current consumption below 10uA?

What UART do you have enabled? Erratum 89 describes a problem where you have to power cycle some of the peripherals using EasyDMA in order to disable them properly, please see this post for instructions on that with UARTE or UARTE1. Keep in mind that you have to reinitialize the UARTE peripheral again in order to turn it back on.

You could also use UART without EasyDMA in order to avoid this altogether.

Best regards,

Simon

RE: Enter in SYSTEM ON doest not work

Louis Hatte — Fri, 19 Jul 2019 16:35:08 GMT

Hey Simonr,

Thanks for your help

We have switched back to the NRF52 DK to reproduce your test and we had 4µA with RTT logging only. It's still not the 2.3µA you have, but it's good enough for us.
From this solid base, we have tried to gradually re-implement our project in this template to see what draws current.

When using the UART Driver (APP_UART_FIFO_INIT) followed by app_uart_close to the peripheral, we have about 890µA when we expect to have the 4µA measured just before.

We have found many post on this subject, but none answered....

How to correctly use the UART Driver for low power consumption ?

Thanks

RE: Enter in SYSTEM ON doest not work

Simonr — Fri, 19 Jul 2019 06:09:13 GMT

Hi Louis

The culprits of current consumption in the pwr_mgmt example are these functions:

APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
NRF_LOG_DEFAULT_BACKENDS_INIT();

NRF_LOG_INFO("Power Management example");

Logging does use power, as it initializes a few peripherals, I.E. UART or RTT depending on which one you use for logging. You can check by "un-commenting" these three lines from your main, and you'll see the 570uA draw again.

Best regards,

Simon

RE: Enter in SYSTEM ON doest not work

Louis Hatte — Thu, 18 Jul 2019 14:39:05 GMT

Hi Simonr

I returned into my application project code and:

1. Set DCDC mode in my main

2. Enable NRF_PWR_MGMT_CONFIG_USE_SCHEDULER in my SDK config

3. Fix an external peripheral problem ( which was drawning the 2 mA .... )

Now I measure ~580µA when I'm in SYSTEM ON just like you in your pwr_mgmt project.

I would like to go below 10µA, but i don't understand how the lines i have commented out in the pwr_mgmt project brought you from 570µA to 2.3µA.
From my understanding, i have only commented Logs and AppScheduler which are not supposed to consume extra power.

Why do you get 2.3µA instead of 570µA when commenting lines I commented in pwr_mgmt example ?

Thanks

RE: Enter in SYSTEM ON doest not work

Simonr — Thu, 18 Jul 2019 06:15:05 GMT

Hi Louis

How are you measuring your current consumption? I just tested the pwr_mgmt example myself and were able to measure ~570uA when the application was running, and ~0.3uA when I pressed button 1 to go to sleep mode using the PPK and an nRF52840DK. Additionally, when commenting out the same lines as you, I get a constant 2.3uA current using the same measurement setup.

Best regards,

Simon

RE: Enter in SYSTEM ON doest not work

Louis Hatte — Wed, 17 Jul 2019 14:11:58 GMT

If I unplug my JLink from my custom board I get 2.6 mA on pwr_mgmt example too.

RE: Enter in SYSTEM ON doest not work

Louis Hatte — Wed, 17 Jul 2019 13:41:02 GMT

Hi Simonr

I tried with idle_state_handle function and now I have 2.6 mA instead of 1.5 uA.

I compiled and run the pwr_mgmt example with no modification except commenting some lines like so:

int main(void)
{
    // APP_ERROR_CHECK(NRF_LOG_INIT(NULL));
    // NRF_LOG_DEFAULT_BACKENDS_INIT();

    // NRF_LOG_INFO("Power Management example");

    lfclk_config();

    uint32_t err_code = app_timer_init();
    APP_ERROR_CHECK(err_code);

// #if NRF_PWR_MGMT_CONFIG_USE_SCHEDULER
//     APP_SCHED_INIT(APP_SCHED_MAX_EVENT_SIZE, APP_SCHED_QUEUE_SIZE);
// #endif // NRF_PWR_MGMT_CONFIG_USE_SCHEDULER
    // bsp_configuration();

    ret_code_t ret_code = nrf_pwr_mgmt_init();
    APP_ERROR_CHECK(ret_code);

    while (true)
    {
// #if NRF_PWR_MGMT_CONFIG_USE_SCHEDULER
//         app_sched_execute();
// #endif // NRF_PWR_MGMT_CONFIG_USE_SCHEDULER

        if (NRF_LOG_PROCESS() == false)
        {
            nrf_pwr_mgmt_run();
        }
    }
}

and my consommation is 4 mA..

I don't know how to get 1.5 uA.

Any ideas?

RE: Enter in SYSTEM ON doest not work

Simonr — Wed, 17 Jul 2019 12:15:08 GMT

Hi Louis

As stated in the link you provided, this means the CPU is still running for some reason. Seeing as you're using a logger, I assume your application doesn't handle pending log operations before it goes to sleep, which causes the CPU to keep running.

Could you try adding the idle_state_handle(); in your for loop instead of the nrf_pwr_mgmt_run(); as idle_state_handle(); handles pending log operations, then sleeps until the next event occurs.

/**@brief Function for handling the idle state (main loop).
 *
 * @details Handle any pending log operation(s), then sleep until the next event occurs.
 */
static void idle_state_handle(void)
{
    if (NRF_LOG_PROCESS() == false)
    {
        nrf_pwr_mgmt_run();
    }
}

Due to the summer holidays in Norway, our support team is understaffed this week, and delayed replies must be expected. Sorry for the inconvenience!

Best regards,

Simon