FUJITSU Semiconductor Controller MB89950/950A - Manual (Page 170)

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CHAPTER 8 PULSE WIDTH COUNT TIMER (PWC)
8.5 Operation of Interval Timer Function
This section describes the operation of the interval timer function of the pulse width
count timer.
■ Operation of interval timer function
The interval timer function can operate as a continuous timer (reload timer mode), or as a timer that
operates for one timer-cycle and then stops (one-shot mode).
●
Reload timer mode
Figure 8.5-1 "Interval timer function (reload timer mode) settings" shows the settings required to operate in
reload timer mode.
Figure 8.5-1 Interval timer function (reload timer mode) settings
On activation, the RLBR register value is loaded to the counter and the counter starts to count down on the
rising edge of the selected count clock. When the counter value underflows (01
H
--> 00
H
), the PWC inverts
the timer output bit (PCR2: TO) value, reloads the RLBR register value to the counter, and sets the
underflow (01
H
--> 00
H
) interrupt request flag bit (PCR1: UF = "1") on the next rising edge of the count
clock.
Figure 8.5-2 "Operation in reload timer mode" shows the operation in reload timer mode.
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
PCR1 EN IE UF IR BF
1 X X
X X
X
PCR2 FC RM TO C1 C0 W1 W0
0 0
RLBR Sets interval time (counter initial value).
: Used bit
: Unused bit
1 : Set "1".
0 : Set "0".