A reader for an RFID system includes an internal power source, a signal generator for generating a detection signal containing analog data and an excitation signal, a transmitting antenna for transmitting the detection and excitation signals, and a receiving antenna for receiving a transponder data signal from a transponder containing digital data. Receiver electronics are coupled with the receiving antenna for conditioning the transponder data signal before reading the digital data. The reader further includes a single-chip microcontroller coupled with the internal power source and the receiver electronics. The single-chip microcontroller has an analog to digital converter to measure the declining power level of the internal power source and to acquire the analog data from the detection signal and the digital data from the transponder data signal. The single-chip microcontroller also includes a firmware and/or software-based demodulator for demodulating the transponder data signal to read the digital data.