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5.6 Notes on Using Timebase Timer
5.6
Notes on Using Timebase Timer
This section lists points to note when using the timebase timer.
s Notes on Using Timebase Timer
r Notes on setting bits by program
The system cannot recover from interrupt processing if the overflow interrupt request flag bit
(TBTC: TBOC) is "1" and the interrupt request enable bit is enabled (TBTC: TBIE = "1"). Always
clear the TBOF bit.
r Clearing timebase timer
In addition to being cleared by the timebase timer initialization bit (TBTC: TBR = "0"), the timer
is cleared whenever the main clock oscillation stabilization delay time is required. When the
timebase timer is selected as a count clock of the watchdog timer, clearing the timebase timer
also clears the watchdog timer.
r Using as timer for oscillation stabilization delay time
As the main clock source oscillation is stopped when the power is turned on during main-stop
mode, and during subclock mode, the timebase timer provides the oscillation stabilization delay
time after the oscillator starts.
An appropriate oscillation stabilization delay time must be selected for the type of resonator
connected to the main clock oscillator (clock generator).
Reference:
See Section 3.6.1 "Clock Generator Section".
r Notes on peripheral functions that provided a clock supply from timebase timer
In modes in which the main clock source oscillation is stopped, the timebase timer also stops,
and the counter is cleared. As the clock derived from the timebase timer restarts output from its
initial state when the timebase timer counter is cleared, the "H" level may be shorter or the "L"
level longer by a maximum of half cycle. The clock of the watchdog timer also restarts output
from its initial state. However, as the watchdog timer counter is cleared at the same time, the
watchdog timer operates in normal cycle.
Figure 5.6-1 "Effect on Buzzer Output of Clearing Timebase Timer" shows the effect on the
buzzer output of clearing the timebase timer.