cpu idle and sd_app_event_wait in NRF51

[steven]

hi,

According to nRF51_reference_manual doc and Relate Discuss. I think that power mode have system on(run/idle) and system off and at system on idle(sleep) mode which contain Constant Latency and Low Power(default).

how to select the system on idle mode is Constant Latency or Low Power? automatically select depending on peripheral ?or how much power is needed .? when i save power ,so we should be into idle mode? in the idle mode the power how to Calculate? (spi' rtc(app timer)'pwm(gpiote)..at adversting modle and connect mode.)

when idle mode the current should be Ion+Irtc+Ix32 about 5uA. right? In this mode should need softdevice or other setting? why i Measure 4mA.

int main(void)
{
    // Initialize
   int i=0;
    for (;;)
    {
        //app_sched_execute();
        power_manage();
    }
}

/**@brief Function for the Power manager.
 */
static void power_manage(void)
{
	uint32_t err_code;
	uint8_t softdevice_enabled;
	err_code=sd_softdevice_is_enabled(&softdevice_enabled);
	if(softdevice_enabled)
	{		
    err_code = sd_app_event_wait();
    APP_ERROR_CHECK(err_code);
	}
	else
	{
		__WFE();  
    __SEV();
    __WFE();
	}
}

run ble sample , and set long ADVERTISING interval time 1s. It should be at idle mode . that get 210uA.

int main(void)
{
    // Initialize
    leds_init();
    timers_init();
    gpiote_init();
    buttons_init();
    ble_stack_init();
    scheduler_init();
    gap_params_init();
    advertising_init();
    services_init();
    conn_params_init();
    sec_params_init();
    
    // Start execution
    timers_start();
    advertising_start();
    
    // Enter main loop
    for (;;)
    {
        app_sched_execute();
        power_manage();
        nrf_gpio_pin_toggle(ADVERTISING_LED_PIN_NO);
    }
}

ble_app_template.zip

[Ole Morten]

You can switch between constant latency and low power by triggering the tasks in NRF_POWER, TASKS_CONSTLAT and TASKS_LOWPWR

If you measure 4 mA, the CPU doesn't actually go to sleep, but stays in an infinite loop somewhere. I'd recommend you to try running the project with a debugger to see where it hangs.

To measure low currents you should also make sure to disconnect the Segger, either by removing the cable or by turning off the switch on the Evaluation Kit. On the Development Kit, you should also not use header K1 for measuring < 100 µA currents, as that will be very imprecise due to the opamp.

[steven]

hi, about the idle mode current. the i erase the Flash , and re-program the flash. rebuild the project optimization(keil c, compiler -O3,use microLIB and Cross-Module Optimization)

i have get the low power.

why the compiler option make current variance?

[Ole Morten]

It would be expected to see some lower average current when having optimizations enabled, but the idle currents should not be affected. If they are I suspect that there is something odd about your code, but it's impossible to say for sure without seeing your complete project.

[steven]

thank your reply. i see it .