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CHAPTER 11 TIMEBASE TIMER
11.1 Overview of Timebase Timer
The timebase timer is an 18-bit free-run counter (timebase timer counter) that
increments in synchronization with the main clock (half frequency of main oscillation
clock).
• Four interval times can be selected and an interrupt request can be generated for
each interval time.
• An operation clock is supplied to the oscillation stabilization wait time timer and
other peripherals.
■ Interval Timer Function
• When the timebase timer counter reaches the interval time set by the interval time select bits (TBTC:
TBC1, TBC0), an overflow (carrying) occurs (TBTC: TBOF = 1) and an interrupt request is generated.
• When an interrupt is enabled when an overflow occurs (TBTC: TBIE = 1), an overflow occurs (TBTC:
TBOF = 1) and an interrupt is generated.
• The timebase timer has four interval times that can be selected. Table 11.1-1 shows the interval times of
the timebase timer.
Table 11.1-1 Interval Times of Timebase Timer
Count clock Interval time
2/HCLK(0.5 µs)
2
12
/HCLK (approx. 1.0 ms)
2
14
/HCLK (approx. 4.1 ms)
2
16
/HCLK (approx. 16.4 ms)
2
19
/HCLK (approx. 131.1 ms)
HCLK: Oscillation clock
The parenthesized values are provided at 4-MHz oscillation clock.