LIS2DW can not wake nRF52805 module up!

[paul0208]

Hi,

I'm using nRF52805 with LIS2DW, accelerometer.

LIS2DW is controlled by I2C protocol. but I do not use nrf I2C driver. I am using two GPIO port emulating I2C. It works well.

After program is started, I set LIS2DW register to make interrupt when some movement is sensed.

When I set nRF52 as follow when go to deep sleep.

    nrf_gpio_pin_sense_t sens = NRF_GPIO_PIN_SENSE_HIGH;

    nrf_gpio_cfg_sense_set (LIS2DW_INT1_PIN, sens);

I shake my board, nRF52 is wake up properly. But, normally, my module consume the power about 100uA.

To reduce the power consumption, I use one GPIO to pull-up resister;s Voltage of I2C SDA and SCL line.

Before set LIS2DW registers, I set SDA and SCL port to output, and do set LIS2DW register.

After setting LIS2DW, I set SDA and SCL port to input to reduce the power consumption,

At this state, about 8~9uA is consumed.

After for a while, Module go to deep sleep, current is change to 1~2uA.

And when I shake my module, my module does not wake up.

When I do not set SDA and SCL pin to input, my module is wake up.

For SDA and SCL is set to outport, current is about 100uA and wakeup is working.

For SDA and SCL is set to input just before deep sleep, current is about 1~2uA, but no wake up.

What is problem?

BR

Paul

[Simonr]

Hi Paul

What sleep mode are you entering exactly? If it's in system off it needs an external event to be woken up? Does the LIS2DW generate an event on these pins that is able to wake the nRF from system OFF mode? 

This case on wake up issues may be helpful as some users and my colleague Einar has a long and in-depth discussion on reasons why the device isn't waking up as predicted in all cases.

Best regards,

Simon

[paul0208]

Hi,

I use as like:

nrf_gpio_pin_sense_t sens = NRF_GPIO_PIN_SENSE_HIGH;
nrf_gpio_cfg_sense_set (LIS2DW_INT1_PIN, sens);
sd_power_system_off();

Yes. I need external event.

I want this event is from LIS2DW.

THX