diode. For the supply a DC-DC converter is used with an
input voltage range from 0.5V to 5V to enable operation from
different battery cell types and even from nearly discharged
cells. The wireless connection is provided by an RF-IC for
433 MHz ISM band. An OOK modulation with a proprietary
protocol is used for the uplink communication. This RF-IC
[20] has no need for an external Chrystal-Oscillator. It is
intended to integrate all the sensor hardware in a single IC
in the future of the project.