| 摘要 |
PURPOSE:To obtain stable operational conditions without any malfunction by detecting the malfunction of a programmable IC and by informing it to the CPU side. CONSTITUTION:An output port P1 of a pogrammable IC5 set to an output port at a normal condition, and its output level changes an H and an L. When noise enters and an action mode of the IC5 is released, the port P1 becomes high impedance; therefore it stops at a voltage V0 divided by voltage-dividing resistances R1 and R2. If an action voltage of a window comparator 6 is set to V1>V0>V2, an output of an AND gate 13 becomes a high level only when a voltage of the port P1 is between V1-V2. After delay time by a CR delay circuit 14 elapses, a high level signal is transmitted to a CPU1. By this signal the CPU1 executes action mode setting of the IC5 again. Thus malfunctions due to noises can be detected, and automatic restoration can be possible. |
