public RTC_Controller(string I2Cbus, int SQW_pin_n,
IPinFunctionPolicy i2c_pin_policy)
{
i2c_pin_policy.SetPinAlternate();
clock = DS1307.CreateDevice(I2Cbus);
SQW_pin = GpioController.GetDefault().OpenPin(SQW_pin_n);
SQW_pin.SetDriveMode(GpioPinDriveMode.Input);
Sync_clocks();
Enable_SQW();
}