I use mbed to write the application on to the board FRDM-KL46Z.
The board is powered with Vin 5-9V.
Application runs, but reading the time with
time_t seconds = time(NULL);
will get the same result until the board is powered
with the USB cable at the OpenSDA port in addition.
Is there a chance to power up the board without
the USB cable to keep RTC running?