**2.2.4 MCU data controller**

26 Health Management – Different Approaches and Solutions

 (a) (b)

(c)

Fig. 7. Biosignal recorder (a) recorder with case closed, (b) recorder with case opened, (c)

portable recorder with wires attached to user's body

Fig. 8. Block diagram of developed biosignal recorder

The data controller consists of a MCU (Philips P89C51RD2HBP microcontroller), a multiplexer (Hitachi HD74LS153P, Dual 4-line to one-line Data Selectors), a demultiplexer (SN74LS156N, Dual one-line to 4-line Data Decoder), and a RS232-TTL voltage conversion IC (Intersil HIN232CP). Fig. 9 shows the developed data controller circuit on a breadboard. The function of this data controller is like a data switch to bridge the biosignal recorder and additional sensor to the Bluetooth adaptor. It alternately transmits the data from these two different sensors to the smart phone via Bluetooth.

Fig. 9. MCU Data Controller
