Patent ID: 6914884
Filing Date: 2005-07-05
Classification: H04B,H04L

Abstract:
1. A communication control circuit having a physical layer circuit in conformity with IEEE Standard 1394, wherein said physical layer circuit is provided with: cable drive means for driving an IEEE 1394 cable pursuant to said IEEE Standard 1394 and receiving a signal from said cable, said cable drive means having first and second cable drive means for driving first and second twisted pair cables of said IEEE 1394 cable, said first cable drive means having first terminals for communicating with said first twisted pair cable, first driver for driving said first twisted pair cable through said first terminals, first receiver for receiving signals applied to said first terminals, and a first arbitration comparator for detecting a state of a line connected with said first terminals, the result of detection being a first arbitration control signal, and said second cable drive means having second terminals for communicating with said second twisted pair cable, a second driver for driving said second twisted pair cable through said second terminals, second receiver for receiving signals applied to said second terminals, and a second arbitration comparator for detecting a state of a line connected with said second terminals, the result of detection being a second arbitration control signal; bus arbitration means for controlling transmission and reception of packet data to manage bus arbitration in accordance with said IEEE Standard 1394 based on said first and second arbitration control signals; transmission means for generating a transmission strobe signal and a transmission data signal to transmit through said first and second drivers respectively under control of said bus arbitration means; and reception means for receiving outputs of said first and second receivers under control of said bus arbitration means and supplying predetermined one of said outputs of said first and second receivers as an output; and wherein said physical layer circuit is further provided with a self-diagnosis circuit for diagnosing said physical layer circuit, said self-diagnosis circuit comprising: