MC68HC11F1CFN5 MOTOROLA [Motorola, Inc], MC68HC11F1CFN5 Datasheet - Page 57

• Manufacturer Part Number: MC68HC11F1CFN5
• Description: Technical Summary 8-Bit Microcontroller
• Manufacturer: MOTOROLA [Motorola, Inc]

12 Main Timer
12.1 Timer Operation
MC68HC11F1/FC0
MC68HC11FTS/D
Frequency
E-Clock
The main timer is based on a free-running 16-bit counter with a four-stage programmable prescaler. The
timer drives the three input capture (IC) channels, four output compare (OC) channels, one channel pro-
grammable for either IC or OC, and the pulse accumulator (PA). All of these functions share port A. The
main timer also drives the pulse accumulator, real-time interrupt (RTI), and computer operating properly
(COP) watchdog circuits.
The following tables summarize timing periods for various M68HC11 functions derived from the main
timer for several crystal frequencies.
1 MHz
2 MHz
3 MHz
4 MHz
5 MHz
6 MHz
Any E
1 Count
1.000 s
0.500 s
0.333 s
0.250 s
0.200 s
0.167 s
Frequency
Frequency
E-Clock
E-Clock
1/E
1 MHz
2 MHz
3 MHz
4 MHz
5 MHz
6 MHz
1 MHz
2 MHz
3 MHz
4 MHz
5 MHz
6 MHz
Any E
Any E
PR[1:0] = 00
Table 26 Timer Subsystem Count and Overflow Periods
65.536 ms
32.768 ms
21.845 ms
16.384 ms
13.107 ms
10.923 ms
Overflow
TCNT
2
16
RTR[1:0] = 00
Table 28 COP Watchdog Time-Out Periods
RTR[1:0] = 00
/E
32.768 ms
16.384 ms
10.923 ms
8.192 ms
4.096 ms
2.731 ms
2.048 ms
1.638 ms
1.366 ms
8.192 ms
6.554 ms
5.461 ms
Table 27 Real-Time Interrupt Periods
2
2
13
15
/E
/E
4.000 s
2.000 s
1.333 s
1.000 s
0.800 s
0.667 s
1 Count
4/E
PR[1:0] = 01
RTR[1:0] = 01
RTR[1:0] = 01
262.144 ms
131.072 ms
131.072 ms
87.381 ms
65.536 ms
52.429 ms
43.691 ms
16.384 ms
65.536 ms
43.691 ms
32.768 ms
26.214 ms
21.845 ms
Overflow
8.192 ms
5.461 ms
4.096 ms
3.277 ms
2.731 ms
TCNT
2
2
2
18
14
17
/E
/E
/E
8.000 s
4.000 s
2.667 s
2.000 s
1.600 s
1.333 s
1 Count
RTR[1:0] = 10
RTR[1:0] = 10
8/E
524.288 ms
262.144 ms
174.763 ms
131.072 ms
104.858 ms
32.768 ms
16.384 ms
10.923 ms
87.381 ms
PR[1:0] = 10
8.192 ms
6.554 ms
5.461 ms
2
2
15
19
/E
/E
524.288 ms 16.000 s
262.144 ms
174.763 ms
131.072 ms
104.858 ms
87.381 ms
Overflow
TCNT
2
19
/E
RTR[1:0] = 11
RTR[1:0] = 11
699.051 ms
524.288 ms
419.430 ms
349.525 ms
65.536 ms
32.768 ms
21.845 ms
16.384 ms
13.107 ms
10.923 ms
2.097 s
1.049 s
2
2
8.000 s
5.333 s
4.000 s
3.200 s
2.667 s
1 Count
21
21
16/E
/E
/E
PR[1:0] = 11
MOTOROLA
524.288 ms
349.525 ms
262.144 ms
209.715 ms
174.763 ms
Overflow
1.049 s
TCNT
2
20
/E
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