Design On Visiting Phone System Based On Micro-controller

With the development of modern society, the practical needs of societyconstantly updated, intelligent facilities and equipments abound. The prison is one ofthe judicial systems which is an important part of, is also gradually towardsmodernization. And the prison visiting phone system, which plays a very importantrole of supervise and manage inmates, is an essential part of the prison managementsystem. In this paper, according to some problems of the conventional visiting phonesystem existed, and the actual requirements of the customers, two kinds of visitingphone system base on micro-controller has been designed. That is the sub-wirevisiting phone system and the bus visiting phone system.The sub-wire visiting phone system is with the MCU control at the core,designs on the constant current source power supply circuit, the visiting substationcircuit, the LED display circuit, the power conversion circuits, the monitor andchime in circuit, the recording interface circuit and the appropriate control softwareto control the visiting process, which is a visiting phone system base on the analogsignal transmission.The bus visiting phone system uses the MC145480PCM Codec-Filter for voiceA/D, D/A conversion to digitize the voice, uses the PIC18FXXK80MCU as thesystem control core and constitutes the CAN bus system by the embedded CANcontroller, all the voice digital signal and the control commands are transmitted onthe CAN bus, which is digital and intelligent voice visiting phone systems.And the sub-wire visiting phone system has been produced in large numbers,and is well received in the market. The bus visiting phone system has completed thedebugging of the main functions and has a good foundation for production. The busvisiting phone system, compared with the the sub-wire visiting phone system, ismore humane in the management and monitoring operations, has evident advantagein the cost and installation.