Wakeup from sleep with GPIO

[Marco Russi]

Hi, I would like to put a nrf51822 device into system off mode and wake it up with a GPIO transition from high to low. I would like to measure the press time of the button after wake up but it seems that software doesn't run properly until the button is pressed. So, does the software run normally after the reset transition even if the button is still pressed? I hope it is clear. Thanks.

[RK]

Well the software doesn't run properly until the button is pressed because it's off. After you press the button and the chip resets then of course it will run normally, from the very start of your code. If you want to measure the press time of the button, then you'll have to detect at the start of your code if the button is currently pressed and start timing it, and you'll miss the time it takse for the system to reset itself.

[Marco Russi]

Hi, I did other tests and I can confirm that the software doesn't run during the button is pressed (low pin state started with a high to low transition). It will start to run at the consecutive release event (low to high transition). The button is configure as follow: nrf_gpio_cfg_sense_input(BUTTON_PIN_NUMBER, NRF_GPIO_PIN_PULLUP, NRF_GPIO_PIN_SENSE_LOW);