| 摘要 |
PURPOSE:To judge the normality of a barrel shifter by itself and to prevent the output of an erroneous shift result by providing a self-test circuit to the barrel shifter. CONSTITUTION:A comparator 6 is provided to execute the test of a barrel shifter 4 and a test enable signal TE is sent to an output latch 5 and the comparator 6. Thus, the latch returns the shift result and further, the shift result is inputted to the comparator 6. On the other hand, the storage output of an input latch 3 is sent to the comparator 6. In the circuit 6, the two inputs are compared and the comparison result is sent as a signal EER to a CPU 1 in response to the signal TE. Consequently, the CPU 1 can decide the normality of the action of the shifter 4 to shifted data and shift control data of an arbitrary pattern. |
