Patent ID: 6640338
Filing Date: 2003-10-28
Classification: G06F,H04H

Abstract:
An electronic device for a cable broadcasting system for processing transmission signals passing through a transmission line and provided on the transmission line from a center equipment to a terminal device, comprising:a receiving circuit connected from the transmission line for receiving broadcast signals including command signals, a control circuit including a microcomputer for setting and controlling an operating mode of the electronic device, including distribution of the broadcast signals to recipients according to command signals, the microcomputer including a microcomputer timer counting an input stop period and generating a periodic pulse signal, the periodic pulse signal indicating normal operation of the microcomputer and cessation of the periodic pulse signal indicating a malfunction of the microcomputer, and determining a command signal interval between receiving command signals from the receiving circuit, the microcomputer terminating operation microcomputer when a command signal is not received within the predetermined command signal interval, thereby terminating generating of the periodic pulse signal generated by the microcomputer, and a watchdog timer counting an output stop period and generating a microcomputer reset signal to the microcomputer when a pulse signal is not received within an output stop period abnormality time, wherein the output stop period count is reset to a beginning of the output stop period upon each occurrence of the pulse signal generated by the microcomputer, and the generation of the pulse signal within the input stop period represents normal operation of the input from the receiving circuit to the microcomputer and the generation of the pulse signal within the output stop period abnormality time indicates normal operation of the microcomputer.