MB90560 Datasheet, PDF (256/581 Pages) Fujitsu Component Limited. – 16-BIT MICROCONTROLLER

9.6 Usage Notes on the Timebase Timer
Notes about the effects on peripheral functions of clearing interrupt requests and the
timebase timer are given below.
s Timebase timer usage notes
q Clearing interrupt requests
The TBOF bit of the timebase timer control register must be cleared while a timebase timer
interrupt is masked by the TBIE bit or the interrupt level mask register (ILM) of the processor
status (PS).
q Effects of timebase timer clearing
Clearing of the timebase timer counter affects the following operations:
• When the timebase timer is using the interval timer function (interval interrupt)
• When the watchdog timer is being used
q Use of the timebase timer as the oscillation settling time timer
At power-on, the source oscillation of the main clock stops in main stop mode. After oscillator
operation starts, the operating clock supplied by the timebase timer is used to take the oscillation
stabilization wait time of the main clock. An appropriate oscillation stabilization wait time must be
selected based on the type of oscillating element connected to the main clock oscillator (clock
generation section). See Section 4.5, "Oscillation Stabilization Wait Time," for details.
q Notes on peripheral functions to which clocks are supplied from the timebase timer
In the mode in which the main clock source oscillation stops, the counter is cleared and
timebase timer operation stops. When the timebase timer counter is cleared, the clock supplied
from the timebase timer is supplied from its initial state. As a result, the H level is shortened and
the L level lengthened 1/2 cycle. Although the clock for the watchdog timer is also supplied from
its initial state; the watchdog timer operates in normal cycles because the watchdog timer
counter is cleared at the same time.
Counter value
00FFFH
00800H
00000H
Clearing the counter by the program (TBTC: TBR = “0”)
Clock supplied to PPG
PPG can be operated by supplying count clock from the timebase timer (Divide-by-512 source oscillation)
Figure 9.6-1 Effect on PPG when clearing timebase timer
232 CHAPTER 9 TIMEBASE TIMER
MB90560 series