| 摘要 |
PROBLEM TO BE SOLVED: To provide a nonvolatile memory writer capable of preventing the erroneous write of a nonvolatile memory. SOLUTION: An ECU 1 is provided with a power source IC 2, a main microcomputer 3, a sub-microcomputer 4 and an EEPROM 7 or the like. When a power supply voltage Vcc becomes equal to or lower than a prescribed reset voltage, the power source IC 2 outputs a reset signal S2 to the main microcomputer 3. Data are written on the EEPROM 7 by the sub-microcomputer 4. In the ECU 1, the bottom operating voltage of the main microcomputer 3 is lower than the reset voltage and the bottom operating voltage of the sub- microcomputer 4 is higher than the reset voltage. When lowering the power supply voltage Vcc to the bottom operating voltage of the sub-microcomputer 4, the main microcomputer 3 inhibits the write of the EEPROM 7 from the sub-microcomputer 4 by turning an output terminal CS1 into 'L' level. |
