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7. Interfacing to computer

 

It is important to read memory contents of ITDL through a computer for future improvement and further expansions of the system by software modifications. Therefore, to facilitate that and to download the stored data to a computer, an RS232 serial Driver/Receiver is associated to the system. Hence, analysis report of telephone calls together with call charges can be calculated and printed with an application software.

 

Fig. 5 Illustration of computer interfacing to ITDL 

 

Fig.5 depicts the link between Z80 PIO and RS232 serial port of computer. The capacitors C7, C8, C9 and C10 form a voltage-doubling network together with internal converters of MAX232 to satisfy its operational conditions.

 

One pair of Driver/Receiver has been chosen for the application and PA6 and PA7 of Z80 PIO establish transmitter and receiver path respectively. Further, 9 pin serial port of the computer is connected via a cable to the ITDL serial port as shown in the diagram. The transistor T1 and associated LED circuit provide visual indication of proper connection between ITDL and computer while blinking LED signifies that the data are being downloaded.  

 

 

 

 

 

 

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Last modified: July 13, 2002