Test circuit with physical layer device and test circuit with link layer device

摘要

PROBLEM TO BE SOLVED: To provide a link layer device with testing circuit for eliminating usual inconvenience by enabling to measure the AC timing by a link layer device single body and enabling to measure by changing measuring conditions such as temperature and source voltage by using a general purpose board. SOLUTION: When a testing circuit 21 generates a testing signal by a testing mode signal, this testing signal is supplied to a sequencer 15. The sequencer 15 controls so that a transmitting circuit 18 periodically forms a cycle start packet by linking with a cycle timer-monitor 17 on the basis of the testing signal. As a result, the transmitting circuit 18 forms the cycle start packet in synchronism with a system clock SC1k. A signal applied to this formed cycle start packet is outputted outside via a physical layer interface 20.