| 摘要 |
PURPOSE:To surely detect a data error by comparing a parity check code calculated immediately after the turning-OFF of power and the parity check code calculated immediately after the turning-ON of the power. CONSTITUTION:The power is supplied to the power input terminal 1a of a microcomputer 1 from a DC power source +B through a diode 4. The power input terminal 1a is connected to a holding capacitor 2 as well, and back-up power is supplied to it from a back-up power source 3 through the diode 5. The DC power +B is supplied to an electricity decrease detector 6 too, and its detected output is supplied to a back-up mode control terminal 1b. In this case, when the power is turned OFF, the parity check code is calculated so as to meet necessary data in a memory, and is recorded in the same memory, and a device is turned into a back-up mode. Afterward, when the power is turned ON, the parity check code is calculated again so as to meet the held necessary data, and is compared with the parity check code calculated at the time of the turning-OFF of the power. Thus, the breakdown of the data is surely detected. |
