So far the system consists mostly of  I2C devices, which can be easily controlled with the Arduino Nano, libraries for most sensors exist. A minor challenge is that both GPS and Bluetooth use the serial port, one of them has therefore to revert to a software serial port. Since GPS will be checked if needed, while the Bluetooth communication can be also triggered from outside, the Software Serial port will be used for the GPS module. The Bluetooth module can therefore listen with Hardware-Read if messages arrive, while messages from the GPS module should only arrive if requested.

This setup might change if we switch to a another wireless communication method. ZigBee would still use the serial connection, but other mesh network able communication devices (RFM 70) use other serial protocols, which might allow to get away from this software solution