Communication control circuit

摘要

The invention provides a communication control device that includes a self-diagnostic test circuit capable of executing an operation test. The communication control circuit includes a PHY circuit on an LSI with little trouble, and at a operating speed that is equivalent to actual operation. The self-diagnostic test circuit includes: test data creation circuit for creating test data; expected value data creation circuit for creating expected values of the test data after processing; an arbitration signal switching circuit that switches arbitration signals such that test data supplied from the output driver can be received by a receiver of the same twisted-pair drive block as the output driver; and a comparison circuit that compares test data supplied from an output driver and received by a receiver of the same twisted-pair drive block as the output driver with the expected value data and creates match flags.