zunoEM4EnablePinWakeup()
Enables pin to wake up Z-Uno from most efficient energy saving mode. Only some pins are available in EM4 mode. The full list of suitable pins is #2, #4(A1), #11, #16(PW4), #18, #23(BTN). Pins #18 and #23(BTN) are enabled by default. You have to call this function on every boot (every time setup() function was called). Look at ZUNO_SETUP_SLEEPING_MODE() for code example and details.zunoEM4EnablePinWakeup(pin)