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C509-L_97 Datasheet, PDF (105/290 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller
On-Chip Peripheral Components
C509-L
6.2.5 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 6-16. TL0 uses the timer 0 control bits:
C/T, GATE, TR0, INT0, and TF0. TH0 is locked into a timer function 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, timer 1 can be turned on and off by switching it out of and 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.
Figure 6-16
Timer/Counter 0, Mode 3: Two 8-Bit Timer/Counter
Semiconductor Group
6-27
1997-10-01