| 摘要 |
PURPOSE:To diagnose exactly transmitting and receiving circuits for serial interface, by shifting-in again a shift-out data to a transmitting and receiving both use shift register through a closed loop, and making the shift quantity larger than the number of bits of a data set to the transmitting and receiving body use shift register. CONSTITUTION:When diagnosing a transmitting and receiving both use shift register 6 and a sampling circuit 5, first of all, a data, for instance, a data A ''10111000P'' (P denotes a parity bit generated by a hardware) is set to the transmitting and receiving both use shift register 6, and thereafter, the shift quantity is set to 10 being more than data length (9 bits) by one by a shift quantity controlling circuit 7, and the data A is shifted and sent out from the transmitting and receiving both use shift register 6. The data sent to the sampling circuit 5 is converted in this circuit, and thereafter, 1 bit each is set to the transmitting and receiving both use shift register 6. As for the data at the point of time when the shift quantity becomes 10, the contents are equal to those of the data A, but the bit position is different and is shifted by one bit. Accordingly, the diagnosis can be executed. |
