W741E20X Datasheet, PDF (11/84 Pages) Winbond – 4-BIT FLASH MICROCONTROLLER

Preliminary W741E20X
Timer/Counter
Timer 0 (TM0)
Timer 0 (TM0) is a programmable 8-bit binary down-counter. The specified value can be loaded into
TM0 by executing the MOV TM0L(TM0H), R or MOV TM0, #I instruction. When the MOV TM0L
(TM0H), R instructions are executed, the TM0 will stop down-counting (if the TM0 is down-counting),
the MR0.3 will be reset to 0, and the specified value is loaded into TM0. If MR0.3 is set to 1, the event
flag 1 (EVF.1) is reset and the TM0 starts to count. When it decrements to FFH, Timer 0 stops
operating and generates an underflow (EVF.1 = 1). The interrupt is executed if the Timer 0 interrupt
enable flag has been set (IEF.1 = 1); and the hold state is terminated if the hold release enable flag 1
has been set (HEF.1 = 1). The Timer 0 clock input can be set as FOSC/1024 or FOSC/4 by setting
MR0.0 to 1 or by resetting MR0.0 to 0. The default timer value is FOSC/4. The organization of Timer 0
is shown in Figure 5.
If the Timer 0 clock input is Fosc/4, then:
Desired time 0 interval = (preset value +1) × 4 × 1/Fosc
If the Timer 0 clock input is Fosc/1024, then:
Desired time 0 interval = (preset value +1) × 1024 × 1/Fosc
Preset value: Decimal number of Timer 0 preset value
Fosc: Clock oscillation frequency
Fosc/1024
Fosc/4
1. Reset
2. CLR EVF, #02H
3. Reset MR0.3 to 0
4. MOV TM0L, R or MOV TM0H, R
MR0.0
Disable
Enable
1. Set MR0.3 to 1
2. MOV TM0, #I
8-bit Binary
Down Counter
(Timer 0)
4
4
8
SQ
R _EVF.1
MOV TM0H, R
MOV TM0L, R
MOV TM0, #I
HEF.1
IEF.1
Hold mode release (HCF.1)
Timer 0 interrupt (INT1)
1. Reset
2. CLR EVF, #02H
3. Set MR0.3 to 1
4. MOV TM0, #I
Figure 5. Organization of Timer 0
Timer 1 (TM1)
Timer 1 (TM1) is also a programmable 8-bit binary down counter, as shown in Figure 6. Timer 1 can
be used as a counter to count external events or to output an arbitrary frequency to the MFP pin. The
input clock of Timer 1 can be one of three sources: Fosc/64, Fosc, or an external clock from the RC.0
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Publication Release Date: March 1998
Revision A1