allocatePin method
Check that the pin can be used for GPIO and that is has not already been allocated. This should be called by subclasses not clients.
Implementation
void allocatePin(int physicalPin) {
if (physicalPin < 0 ||
physicalPin >= physToBcmGpioRPi2.length ||
physToBcmGpioRPi2[physicalPin] < 0) {
throw GpioException('Invalid pin', physicalPin);
}
if (_allocatedPins.contains(physicalPin)) {
throwPinAlreadyAllocated(physicalPin);
}
_allocatedPins.add(physicalPin);
}