CONTROLLER

PURPOSE:To attain the high speed of the processing of a microprocessor by performing an access to a peripheral I/O at an appropriate timing corresponding to a battery voltage by the microprocessor. CONSTITUTION:The output voltage of a reference voltage preparing means 7 which prepares a certain reference voltage from the output of a battery 5 is compared with the output voltage of a voltage dividing means 8 which voltage-divides the output voltage of the battery 5 at a certain rate by a voltage comparing means 9, and the active time width of a weight signal inputted from a weight signal generating means 10 to a microprocessor 1 is changed according to an output signal from the voltage comparing means 9. Therefore, the change of the battery voltage can be detected by the weight signal generating means 10, and the active time width of the weight signal inputted to the microprocessor 1 can be changed according to the change of the battery voltage. Thus, the access to a peripheral I/O 2 can be performed at the appropriate timing corresponding to the battery voltage by the microprocessor 1.