| 摘要 |
<p>PURPOSE:To secure the correctness of a frequency even in an oscillation circuit whose start-up time is short by controlling the frequency by measuring the operating clock of a timer/counter itself by the timer/counter including a crystal oscillator. CONSTITUTION:A clock signal generating part 3 includes a self-running oscillation circuit consisting of a resistor and a capacitor and generates a reference clock signal, and the timer/counter 13 includes a crystal oscillation circuit, and selects the oscillation signal, the reference clock signal, and an external signal, then, counts the pulses of them. In such a state, the number of pulses of self-running oscillation in the cycle of crystal oscillation or that of pulses of the crystal oscillation in the cycle of the self-running oscillation is counted, and an error for a targeted value is detected from a count value, then, the frequency of the self-running oscillation can be controlled. In such a way, it is possible to obtain a clock generator most suitable for a microcomputer which performs the stoppage and the start-up of the operating clock and with the high correctness of the frequency and the short start-up time of oscillation.</p> |
