Patent ID: 8265890

Claim:
A microcomputer-equipped system for electric power tool, the system comprising: a microcomputer that includes an AD (analog-to-digital) converter and at least one AD port to which an analog signal to be AD converted by the AD converter is inputted; a reference voltage generator that is separately provided from an operation power source of the microcomputer and generates and inputs to the AD port a reference voltage having a predetermined value; a reference data storage unit that prestores reference data which is digital data corresponding to the reference voltage; a first determiner that is provided inside the microcomputer and compares diagnostic data obtained by AD conversion by the AD converter of the reference voltage inputted to the AD port with the reference data stored in the reference data storage unit to determine, in case that difference between the diagnostic data and the reference data is out of a predefined allowable range, that an AD abnormal state has occurred in which a correct result of the AD conversion is unable to be obtained from the AD converter; a signal voltage divider that is provided on a signal path before the analog signal to be AD converted is inputted to the AD converter, and generates a diagnostic analog signal by voltage division of the analog signal at a predefined voltage dividing ratio when an execution command is inputted; and a second determiner that is provided inside the microcomputer, obtains the diagnostic data by directing the AD converter to AD convert the diagnostic analog signal when the voltage division is executed by the signal voltage divider, obtains a comparative data by directing the AD converter to AD convert the analog signal when the voltage division is not executed by the signal voltage divider, compares the obtained diagnostic data and the comparative data, and determines whether the AD abnormal state has occurred based on a result of the comparison.