MC68HC11KW1 Datasheet, PDF (155/238 Pages) Motorola, Inc – High-density complementary metal oxide semiconductor HCMOS) microcontroller unit

The COP watchdog clock input (E/2¹⁵) is tapped off from the free-running counter chain. The COP
automatically times out unless it is serviced within a specific time by a program reset sequence. If
the COP is allowed to time out, a reset is generated, which drives the RESET pin low to reset the
MCU and the external system. Refer to Table 9-1 for crystal related frequencies and periods.
Table 9-1 Timer 1 resolution and capacity
Clock
16.0MHz 4E
Control bits 4.0MHz
E
PR[1:0] 250ns
1/E
00
250 ns
1/E
16.384ms 2¹⁶/E
01
1.0 µs
4/E
65.536ms 2¹⁸/E
10
2.0 µs
8/E
131.07ms 2¹⁹/E
11
4.0 µs
16/E
262.14ms 2²⁰/E
XTAL
E clock
Period
– resolution
– overflow
– resolution
– overflow
– resolution
– overflow
– resolution
– overflow
9.1.1 Timer 1 structure
The functions of Timer 1 share I/O with the pins of port A as follows:
9
Pin Alternative function
PA0 IC3
PA1 IC2
PA2 IC1
PA3 OC5 and/or OC1, or IC4
PA4 OC4 and/or OC1
PA5 OC3 and/or OC1
PA6 OC2 and/or OC1
PA7 PAI and/or OC1
Figure 9-3 shows the Timer 1 capture/compare system block diagram. The port A pin control block
includes logic for timer functions and for general-purpose I/O. For pins PA3, PA2, PA1 and PA0,
this block contains both the edge-detection logic and the control logic that enables the selection
of which edge triggers an input capture. The digital level on PA[3:0] can be read at any time (read
PORTA register), even if the pin is being used for the input capture function. Pins PA[6:3] are used
either for general-purpose I/O, or as output compare pins. When one of these pins is being used
for an output compare function, it cannot be written directly as if it were a general-purpose output.
Each of the output compare functions (OC[5:2]) is related to one of the port A output pins. Output
MC68HC11KW1
TIMING SYSTEM
9-3