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CHAPTER 10 TIME-BASE TIMER
10.1
Overview of the Time-base Timer
The time-base timer is an 18-bit free-run counter (time-base counter) that counts up in
synchronization with the internal count clock (one-half of the source oscillation). The
timer has an interval timer function that can select four intervals.
The time-base timer also has functions for timer output of the oscillation stabilization
time and for supplying the clocks for the watchdog timer.
■ Interval Timer Function
The interval timer function repeatedly generates an interrupt request at a given interval.
• An interrupt request is generated when the interval timer bit for the time-base counter overflows.
• The interval timer bit (interval) can be selected from four types. Table 10.1-1 lists the intervals for the
time-base timer.
Table 10.1-1 Intervals for the Time-base Timer
HCLK: Oscillation clock
Values in parentheses are for a 4 MHz oscillation clock.
206
Internal count clock cycle
2 / HCLK (0.5 µs)
Interval cycle
12
2
/ HCLK (Approx. 1.0 ms)
14
2
/ HCLK (Approx. 4.1 ms)
16
2
/ HCLK (Approx. 16.4 ms)
19
2
/ HCLK (Approx. 131.1 ms)
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