| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a control processor for accurately measuring clock frequencies in a short time without interrupting miniaturization or low costs. SOLUTION: This processor is provided with a normal operation mode and a frequency measurement mode. In this frequency measuring mode, a dimmer control terminal IOT1 originally assigned to a dimmer control signal 54 for controlling the brightness of the back light of a liquid crystal display screen is temporarily used as the output of a 1/n frequency-division signal 53 outputted from a programmable frequency-divider 24. Thus, it is not necessary to especially provide any terminal pin for measuring clock frequencies, and a clock signal 52 can be directly recognized by measuring the 1/n frequency-divided signal 53. Therefore, the clock frequencies can be measured in a sharply short time compared with a conventional manner for checking the clock frequencies for several days by using clock display, and the increase of the number of terminal pins can be escaped so that the miniaturization of a device size and low costs can be attained.</p> |
