Sleep when the button is pressed, and wake up after releasing the button?

[HelloWorld]

I am trying to stop RTC by pressing one button and wake up again by releasing the same button. My RTC now runs around 4 uA while being on system-on sleep mode by __SEV(); __WFE(); __WFE(); However, the current goes to around 200 uA when the button is being hold after pressing. It only goes back to 4 uA if I release the button.

I realized the line below makes the current go to 200 uA.

nrf_gpio_cfg_sense_input(BUTTON_2, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_HIGH);

Is there a way to truely go to sleep when the button is pressed (not released), and wake up after releasing the button?

// Configure BUTTON 2 with SENSE enabled 
nrf_gpio_cfg_sense_input(BUTTON_2, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_HIGH);

while(true)
{     
__SEV();
__WFE();
__WFE();

    // If BUTTON 2 is pressed..
    if(nrf_gpio_pin_read(BUTTON_2) == 0)
    {
        NRF_POWER->SYSTEMOFF = 1;
    }
}

[Jørgen Holmefjord]

Hi,

The increased current is due to the pin being configured with pull-up resistor. When button is pressed, this will cause current draw of ~200 uA. Could you change your application to avoid having to hold the button, for instance by pressing once to stop RTC and one more time to wake from sleep?

Best regards,

Jørgen

[HelloWorld]

If I can't change my requirement, is there a way to solve the problem to lower current draw of ~200 uA? e.g. like the current goes up for the sense but immediately goes back down to less than 10uA

[Jørgen Holmefjord]

You can use an external pullup resistor. Configure the GPIO using NRF_GPIO_PIN_NOPULL:

nrf_gpio_cfg_sense_input(BUTTON_2, NRF_GPIO_PIN_NOPULL, NRF_GPIO_PIN_SENSE_HIGH);

Connect large resistor from GPIO to VDD. 1 MΩ will give you ~3 uA current draw (with VDD = 3V), when pushing the button.