C508_01 Datasheet, PDF (88/267 Pages) Infineon Technologies AG – 8-Bit CMOS Microcontroller

C508
On-Chip Peripheral Components
6.2.1.5 Mode 3
Mode 3 has different effects on Timer 0 and Timer 1. Timer 1 in mode 3 simply holds its
count. The effect is the same as setting TR1 = 0. Timer 0 in mode 3 establishes TL0 and
TH0 as two separate counters. The logic for mode 3 on Timer 0 is shown in Figure 6-12.
TL0 uses the Timer 0 control bits: C/T, Gate, TR0, INT0 and TF0. TH0 is locked into a
timer function (counting machine cycles) and takes over the use of TR1 and TF1 from
Timer 1. Thus, TH0 now controls the “Timer 1” interrupt.
Mode 3 is provided for applications requiring an extra 8-bit timer or counter. When
Timer 0 is in mode 3 and when TR1 is set, Timer 1 can be turned on by switching it to
any mode other than 3 and off by switching it into its own mode 3, or can still be used by
the serial channel as a baudrate generator, or in fact, in any application not requiring an
interrupt from timer 1 itself.
OSC ÷3
P3.4/T0 ^Pin
=1
Gate
C/T = 0
C/T = 1
TR0
TR0
≥1
Control
&
TL0
(8 Bits)
Timer
Clock
TF0
Interrupt
P3.2/INT0 ^Pin
TR1
TH0
(8 Bits)
TF1
Figure 6-12 Timer/Counter 0, Mode 3: Two 8-Bit Timers/Counters
Interrupt
MCS04053
User’s Manual
6-23
2001-05