C504 SIEMENS [Siemens Semiconductor Group], C504 Datasheet - Page 20

• Manufacturer Part Number: C504
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Timer / Counter 0 and 1
Timer/Counter 0 and 1 can be used in four operating modes as listed in table 4.
Table 4
Timer/Counter 0 and 1 Operating Modes
Mode
0
1
2
3
In the “timer” function (C/T = ‘0’) the register is incremented every machine cycle. Therefore the
count rate is
In the “counter” function the register is incremented in response to a 1-to-0 transition at its
corresponding external input pin (P3.4/T0, P3.5/T1). Since it takes two machine cycles to detect a
falling edge the max. count rate is
programmed to function as a gate to facilitate pulse width measurements. Figure 5 illustrates the
input clock logic.
Figure 5
Timer/Counter 0 and 1 Input Clock Logic
Semiconductor Group
Description
8-bit timer/counter with a
divide-by-32 prescaler
16-bit timer/counter
8-bit timer/counter with
8-bit autoreload
Timer/counter 0 used as one
8-bit timer/counter and one
8-bit timer
Timer 1 stops
f
OSC
/12.
f
OSC
/24. External inputs INT0 and INT1 (P3.2, P3.3) can be
Gate
X
X
X
X
20
C/T
X
X
X
X
TMOD
M1
0
1
0
1
M0
0
1
0
1
f
internal
OSC
f
f
f
OSC
OSC
OSC
/
12
/
/
/
12
12
12
Input Clock
32
external (max)
f
OSC
f
f
f
OSC
OSC
OSC
/
24
/
/
/
24
24
24
C504
32