Controller sleep mode and wake up

[PMichael]

Dear Sirs!

I use SDK 12.2. I need without RTOS to put controller in sleep mode (but not OFF mode) and be able to wake it up by pressing button, connected to GPIO.

GPIO with interrupt. I am confused how to do it? Please explain how to set it in deep sleep?.

Will controller perform next instruction after wake up and interrupt processing?

Additional question.

In all examples I see code 

// Activate deep sleep mode
SCB->SCR |= SCB_SCR_SLEEPDEEP_Msk;

But I cannot find in datasheet SCB register and its bits. Where is system control register in datasheet? Different name?

Best regards

[Vidar Berg]

Hello,

Regarding the SCB register, please see my reply in this post:  RE: nrf_pwr_mgmt_run impact of SCB_SCR_SLEEPDEEP_Msk . SCB is an ARM Cortex-specific register. Therefore, it is covered by the ARM documentation and not by our product specification.

GPIO with interrupt. I am confused how to do it? Please explain how to set it in deep sleep?.

You can call power_manage() from your main loop as we do in our examples. This will make the chip enter System ON mode when there is no work to do.

Will controller perform next instruction after wake up and interrupt processing?

The program will return to the code following your sleep function after processing the interrupt(s).

In all examples I see code 

Isn't it only in the FreeRTOS example? Setting this bit is redundant anyway.

Best regards,

Vidar

[PMichael]

Thank you. But function 

static void power_manage(void)
{
uint32_t err_code = sd_app_evt_wait();
APP_ERROR_CHECK(err_code);
}

call softdevice function. I need to do it really in the beginning of start immediately after battery insertion. I need to set controller in sleep mode until button pressed. Pressing button shall switch the device on.

I cannot call any soft device functions.

How to do it without RTOS and without soft device functions?

Thank you

[Vidar Berg]

Thanks for the clarification. But can you also explain why you don't want the chip to enter System OFF mode?

[PMichael]

Because as I know in OFF mode chip cannot wake up from GPIO interrupt. Only reset. May be I am wrong. Please explain

[Vidar Berg]

You can have the device wake-up from a GPIO input event in System OFF mode. The implementation may look something like this:

#include "nrf_gpio.h"


void enter_system_off(void) 
{
    /* Configure wake-up pin */
    nrf_gpio_cfg_sense_input(BUTTON_1, GPIO_PIN_CNF_PULL_Pullup, NRF_GPIO_PIN_SENSE_LOW);

    NRF_POWER->SYSTEMOFF = 1;
    while(1);
}

/**@brief Application main function.
 */
int main(void)
{
    /* Enter system OFF mode after POR/BOR reset and wait for button press to trigger wake-up */
    if (NRF_POWER->RESETREAS == 0)
    {
        enter_system_off();
    }
    ...

[PMichael]

This may be a good solution. But when device wake up from OFF mode, what happen? Reset with RESETREAS register bit RW OFF = 1 ? Is it correct?

[PMichael]

And additional question. What happen with internal pull up resistors in OFF mode? Will it work or I need to add external pull up resistor?

[Vidar Berg]

The GPIO configurations, including the pull-up setting are retained in system OFF.  Please try the code I posted and read the linked documentation.

[PMichael]

Thanks. It was a good idea. It works

[PMichael]

But regarding to all this there is additional question. Is in nRF52832 any general purpose register that I can init with any value before software reset and after software reset read correct value from this register. I need it  to prevent OFF mode after firmware upgrade via BLE