No wake up after LPCOMP set in SYSTEM OFF nrf52 SDK12.1

[Sergy]

Hi,

Im trying to wake up from SYSTEM OFF using LPCOMP.

Im using the following code to power off:

nrf_drv_lpcomp_config_t config = NRF_DRV_LPCONF_DEFAULT_CONFIG;
config.hal.detection=1;
config.hal.reference=1;
config.input = NRF_LPCOMP_INPUT_2;
// initialize LPCOMP driver, from this point LPCOMP will be active and provided
// event handler will be executed when defined action is detected
err_code = nrf_drv_lpcomp_init(&config, wakeUp);
APP_ERROR_CHECK(err_code);
nrf_drv_lpcomp_enable();
sd_power_system_off();

For some reason there is no wake up triggered. Debugger is disconnected.

I know the pin is correct and LPCOMP works in active mode because I use LPCOMP to detect going under voltage to initiate powering off.

Thanks!

[Sigurd]

Hi,

Before going to System OFF mode, you will need to wait for the LPCOMP to be ready. In the product specification its stated that:

After a start-up time of t_LPCOMP,STARTUP the LPCOMP will generate a READY event to indicate
that the comparator is ready to use and the output of the LPCOMP is correct

So change your code to:

nrf_drv_lpcomp_config_t config = NRF_DRV_LPCONF_DEFAULT_CONFIG;
config.hal.detection=1;
config.hal.reference=1;
config.input = NRF_LPCOMP_INPUT_2;
// initialize LPCOMP driver, from this point LPCOMP will be active and provided
// event handler will be executed when defined action is detected
err_code = nrf_drv_lpcomp_init(&config, wakeUp);
APP_ERROR_CHECK(err_code);
nrf_drv_lpcomp_enable();
while(NRF_LPCOMP->EVENTS_READY == 0);
NRF_LPCOMP->EVENTS_READY = 0;
sd_power_system_off();

[Sergy]

Thanks very much Sigurd, that was the problem indeed!