W77E058A40DL Datasheet, PDF (55/87 Pages) Nuvotem Talema – GENERAL DESCRIPTION

W77E058A
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)
GATE = TMOD.3
(GATE = TMOD.7)
INT0 = P3.2
(INT1 = P3.3)
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
TF0
(TF1)
Interrupt
0
7
TH0
(TH1)
Figure 12. Timer/Counter Mode 2.
12.2.4 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.
- 55 -
Publication Release Date: April 17, 2007
Revision A10