W77C58 Datasheet, PDF (49/71 Pages) Winbond – 8 BIT MICROCONTROLLER

Preliminary W77C58
Clock Source
Mode input
div. by 4
osc/1
div. by 64 osc/16
div. by 1024 osc/256
T0 = P3.4
(T1 = P3.5)
TR0 = TCON.4
(TR1 = TCON.6)
T0M = CKCON.3
(T1M = CKCON.4)
1/4
C/T = TMOD.2
1
(C/T = TMOD.6)
1/12
0
0
1
Timer 1 functions are shown in brackets
TL0
(TL1)
0
7
TFx
Interrupt
TF0
(TF1)
GATE = TMOD.3
(GATE = TMOD.7)
INT0 = P3.2
(INT1 = P3.3)
0
7
TH0
(TH1)
Figure 12: Timer/Counter Mode 2
Mode 3
Mode 3 has different operating methods for the two timer/counters. For timer/counter 1, mode 3
simply freezes the counter. Timer/Counter 0, however, configures TL0 and TH0 as two separate 8 bit
count registers in this mode. The logic for this mode is shown in the figure. TL0 uses the
Timer/Counter 0 control bits C/ T , GATE, TR0, INT0 and TF0. The TL0 can be used to count clock
cycles (clock/12 or clock/4) or 1-to-0 transitions on pin T0 as determined by C/ T (TMOD.2). TH0 is
forced as a clock cycle counter (clock/12 or clock/4) and takes over the use of TR1 and TF1 from
Timer/Counter 1. Mode 3 is used in cases where an extra 8 bit timer is needed. With Timer 0 in Mode
3, Timer 1 can still be used in Modes 0, 1 and 2., but its flexibility is somewhat limited. While its basic
functionality is maintained, it no longer has control over its overflow flag TF1 and the enable bit TR1.
Timer 1 can still be used as a timer/counter and retains the use of GATE and INT1 pin. In this
condition it can be turned on and off by switching it out of and into its own Mode 3. It can also be used
as a baud rate generator for the serial port.
Clock Source
Mode input
div. by 4
osc/1
div. by 64 osc/16
div. by 1024 osc/256
T0 = P3.4
TR0 = TCON.4
T0M = CKCON.3
1/4
1
C/T = TMOD.2
0
1/12 0
1
TL0
0
7
GATE = TMOD.3
INT0 = P3.2
TR1 = TCON.6
TH0
0
7
Figure 13. Timer/Counter 0 Mode 3
TF0
Interrupt
TF1
Interrupt
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Publication Release Date: September 1999
Revision A1