nrf52832 sleep mode from android app

[mialo_5]

I am currently looking at how to put the nrf52 development board to sleep (and wake up) by sending a command from an android application (with SDK v15.2).

I have been experimenting with the nrfBlinky app and wanted to know if anyone has some advice on how one would go about doing this.

I have searched the forums but couldn't find a similar question although there are posts about calling __WFE() to put the board in low power mode from the firmware (or calling an event like sd_app_evt_wait()). I did read there are two sleep mode for this board a SYSTEM ON and SYSTEM OFF mode. I am not certain which mode suits the use case best, although I assume we would want the SYSTEM ON mode as the app would need to send an event to wake it up. Although I wouldn't be against a SYSTEM OFF mode where the reset button would need to be pressed to wake it up (so just sending a "put to sleep" command from the app). 

Any advice would be much appreciated.

[Simon]

mialo_5 said:

Therefore based on your reply for Question 1, you mention looking at the ble_uart example which uses a softdevice which I don't believe I am using. Is this then the only way to get the device to sleep in a System OFF mode and why my test didn't work or have I missed something? 

Why does it not work? Have you tried to debug and see what error messages you get?

mialo_5 said:

Therefore based on your reply for Question 1, you mention looking at the ble_uart example which uses a softdevice which I don't believe I am using. Is this then the only way to get the device to sleep in a System OFF mode and why my test didn't work or have I missed something? 

If you want control your device from an android app you need a SoftDevice (which handles all low level BLE activity). The reason I recommended you the ble_app_uart example is because it is a quite simple example which uses the SoftDevice.

[mialo_5]

Thanks for your help although I don't believe I am getting to the answer I'm looking for.

Maybe if I rephrase the question as follows:

I am using the nrfBlinky Android app with an nrf52832. I would like to press a button on the dev board to put the board into a system off (sd_power_system_off() or nrf_pwr_mgmt._shutdown()) sleep mode where I can only recover by pressing RESET button on the board.

If I create a static variable "m_is_sleep_mode" to store if BSP_BUTTON_1 is pressed and check that it is true in the main function (in the for(;;) loop I assume), see code snippet, the board seems to perform a reset (the connection drops and comes back up immediately) but has not gone into a power down mode.

Thoughts this time?

static void button_event_handler(uint8_t pin_no, uint8_t button_action)
{
    ret_code_t err_code;

    switch (pin_no)
    {
        case LEDBUTTON_BUTTON:
            NRF_LOG_INFO("Send button state change.");
            err_code = ble_lbs_on_button_change(m_conn_handle, &m_lbs, button_action);
            if (err_code != NRF_SUCCESS &&
                err_code != BLE_ERROR_INVALID_CONN_HANDLE &&
                err_code != NRF_ERROR_INVALID_STATE &&
                err_code != BLE_ERROR_GATTS_SYS_ATTR_MISSING)
            {
                APP_ERROR_CHECK(err_code);
            }
            break;

        case SLEEPBUTTON_BUTTON:
            m_is_sleep_mode = true;
            break;

        default:
            APP_ERROR_HANDLER(pin_no);
            break;
    }
}

static void buttons_init(void)
{
    ret_code_t err_code;

    //The array must be static because a pointer to it will be saved in the button handler module.
    static app_button_cfg_t buttons[] =
    {
        {LEDBUTTON_BUTTON, false, BUTTON_PULL, button_event_handler},
        {SLEEPBUTTON_BUTTON, false, BUTTON_PULL, button_event_handler}
    };

    err_code = app_button_init(buttons, ARRAY_SIZE(buttons),
                               BUTTON_DETECTION_DELAY);
    APP_ERROR_CHECK(err_code);
}

int main(void)
{
    // Initialize.
    ....

    // Enter main loop.
    for (;;)
    {
        if (m_is_sleep_mode)
        {
            nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF);
        }
        else
        {
            idle_state_handle();        
        }
    }
}

[Simon]

Have you taken a look at the nrf_pwr_mgmt example? That might give you a better understanding of the System OFF sleep mode.

[mialo_5]

Yes

[Simon]

Try changing NRF_PWR_MGMT_SHUTDOWN_GOTO_SYSOFF  with NRF_PWR_MGMT_SHUTDOWN_STAY_IN_SYSOFF.