C505_9708 SIEMENS [Siemens Semiconductor Group], C505_9708 Datasheet - Page 84

• Manufacturer Part Number: C505_9708
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

6.2.1.5
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 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, 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 6-12
Timer/Counter 0, Mode 3: Two 8-Bit Timers/Counters
Semiconductor Group
P3.4/T0
Gate
P3.2/INT0
TR1
Mode 3
= 1
OSC
÷ 6
<
_
1
TR0
f
C/T = 0
C/T = 1
OSC
/6
&
Control
6-22
On-Chip Peripheral Components
(8 Bits)
(8
TH0
TL0
Bits)
Timer Clock
TF0
TF1
C505 / C505C
Interrupt
Interrupt
MCS02729
1997-08-01