| 摘要 |
PURPOSE:To improve the reliability of a control action by setting a program counter in an unpresettable state, applying a loop control structure to a program memory and executing a no-operating instruction when the voltage of a low level of a power supply is detected. CONSTITUTION:A microcomputer contains an address bus 11, a program counter 14, a program memory 15, an arithmetic unit 17, etc. The counter 14 performs its counting action with the clock signal and is set in a preset unable state. A low voltage detecting circuit 21 is also provided to the microcomputer for monitor of the power supply voltage Vdd. Then a no-operating instruction is supplied to an instruction decoder 16 when the Vdd is lowered less than the specific voltage level. Furthermore, the microcomputer is reset when the Vdd has a big drop. The contents of the memory 15 which are read out when the Vdd is reset are carried out. |
