C517A_99 Datasheet, PDF (96/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C517A
6.3.1.2 Timer 2 Operating Modes
Figure 6-14 shows a functional block diagram of the timer 2 unit.
Programmable
OSC
Prescaler
T2PS T2PS1
P1.7/T2
T2I1 T2I0 SFR T2CON
00
01
10
11
No input selected
Timer stop
Timer function
Counter function
via ext. input P1.7/T2
Gated timer function
by ext. input P1.7/T2
Timer 2
Input Clock
P1.5/T2EX
TL2
TH2
(8 Bits) (8 Bits)
TF2
Sync
EXF2
EXEN2
1
Interrupt
1
Reload
MCB03328
Figure 6-14
Block Diagram of Timer 2
Timer mode
In timer function, the count rate is derived from the oscillator frequency. A prescaler offers the
possibility of selecting a count rate of 1/12 to 1/96 of the oscillator frequency. Thus, the 16-bit timer
register (consisting of TH2 and TL2) is incremented at maximum in every machine cycle. The
prescaler is selected by the bits T2PS1and T2PS.
Semiconductor Group
6-30