| 摘要 |
PURPOSE:To perform the test of a single chip microcomputer in real time by inputting an external input signal to a latch circuit in response to the test mode setting signal and deciding the type of the test based on the contents of the latch circuit. CONSTITUTION:When a test is started, a test mode setting signal is inputted to release the reset states of latch circuits 204 - 207. When a CPU 2, a memory 3, and a peripheral circuit 4 are reset by an input reset signal, at the same time, the circuits 204 - 207 are set under the input states to fetch the test instruction signals received from the input terminal I0 - I3. When the reset signal is released, the input states of the circuits 204 - 207 are automatically inhibited and then set under the memory states. Thus an internal resetting action can be carried out simultaneously with a setting action of the test instruction signal. Furthermore the terminals I0 - I3 can be used as the original input ports in a test mode. Thus a single chip microcomputer is tested in real time. |
