| 摘要 |
An integrated circuit comprises a connection port having a serial data input pin and a serial data output pin, on-chip functional circuitry and test logic, and a test access port controller connected to effect communication of serial data across the chip boundary via said input and output pins. The test access port controller is connectable to the test logic in a first mode of operation to effect communication of serial test data under control of an incoming clock signal and being operable in a second mode of operation to communication data as a sequence of serial bits according to a predetermined protocol between the connection port and the on-chip functional circuitry. The integrated circuit includes error detection means for detecting an error condition in the protocol and gating circuitry responsive to detection of the error condition to prevent communication of subsequent data until the error condition is detected as having been removed. <IMAGE> |
