C868_02 Datasheet, PDF (62/244 Pages) Infineon Technologies AG – 8 - Bit CMOS Microcontroller

C868
On-Chip Peripheral Components
4.5.1.5 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 seperate counters. The logic for mode 3 on timer 0 is shown in Figure 4-5.
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 baud rate generator, or in fact, in any application not requiring an interrupt
from timer 1 itself.
f_SYS 12
C/T = 0
=1
Gate
INT0/INT1 ^Pin
Control
TR0
TR0
1
TR1
Timer Clock
TL0
(8 Bits)
TF0
Interrupt
TH0
(8 Bits)
TF1
Interrupt
Figure 4-5 Timer 0, Mode 3: Two 8-Bit Timers/Counters
User’s Manual
4-18
V 0.4, 2002-01