Timebase Timer Operation - Fujitsu F2MC-16LX Hardware Manual

9.5

Timebase Timer Operation

The timebase timer has the interval timer function as well as the clock supplying
function for some peripheral functions.
I Operation of interval timer function (timebase timer)
The interval timer function generates interrupt requests at any defined interval times. For its
operation as an interval timer, the settings shown in Figure 9.5-1 "Timebase timer settings" are
required.
Address
0000A9
: Bits in use
- : Unused bits
0 : 0 is set
1 : 1 is set
• The timebase timer counter continues counting up in synchronization with the internal count
clock (the source clock frequency divided by 2) as long as the clock is oscillating.
• When the counter has been cleared, the up-count starts from "0", and an overflow of the bit
used for the interval timer sets the interrupt request flag bit (TBOF) to "1". In this event, if the
interrupt request output is permitted (TBIE = 1), interrupts are generated at the selected
interval times with the clearing time used as a reference time point.
• The interval time may become longer than the specified time, e, when the timebase timer
was cleared.
I Timer function for Oscillation Stabilization Wait Time
The timebase timer can also be used as the main clock as well as the timer for the oscillation
stabilization wait time of the PLL clock. The oscillation stabilization wait time is the time in which
counting starts when the counter is set to "0" (clearing of counter) and continues until an
overflow occurs in the bit for the oscillation stabilization wait time. However, during return from
the timebase timer mode to the PLL clock mode or main clock mode, the waiting time differs
because the timebase timer counter is not cleared and the time count does not start from zero.
Table 9.5-1 "Timebase timer clear operation and oscillation stabilization wait time" explains the
timebase timer clear operation and oscillation stabilization wait time.
Figure 9.5-1 Timebase timer settings
bit15 bit14 bit13 bit12 bit11 bit10 bit9
RESV
TBTC
H
1
bit8
TBIE TBOF TBR TBC1 TBC0
0 0
CHAPTER 9 TIMEBASE TIMER
bit7 bit15
(WDTC)
197