MC68HC05X4 Datasheet, PDF (112/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
16-Bit Programmable Timer
Counter
The key element in the programmable timer is a 16-bit, free-running
counter, or counter register, preceded by a prescaler that divides the
internal processor clock by four. The prescaler gives the timer a
resolution of 2µs if the internal bus clock is 2MHz. The counter is
incremented during the low portion of the internal bus clock. Software
can read the counter at any time without affecting its value.
Counter registers
Address: $0018
Bit 15
14
13
12
11
10
9
Bit 8
Reset: 1
1
1
1
1
1
1
1
Figure 2. Timer Counter High Register (TCH)
Address: $0019
Bit 7
6
5
4
3
2
1
Bit 0
Reset: 1
1
1
1
1
1
0
0
Figure 3. Timer Counter Low Register (TCL)
MC68HC05X4 Rev 1.0
112
16-Bit Programmable Timer
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4-ptimer
MOTOROLA