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MOTOROLA
MC68341 USER’S MANUAL
8- 25
PREL1
$60C
15
14
13
12
11
10
9876543210
PR1-15
PR1-14
PR1-13
PR1-12
PR1-11
PR1-10
PR1-9
PR1-8
PR1-7
PR1-6
PR1-5
PR1-4
PR1-3
PR1-2
PR1-1
PR1-0
RESET:
1111111111111111
Supervisor/User
For some modes of operation, this register is also used to reload the counter one falling
clock edge after a time-out occurs. Refer to 8.3 Operating Modes for more information on
the individual modes.
8.4.7 Preload 2 Register (PREL2)
PREL2 is used in addition to PREL1 in the variable duty-cycle square-wave generator and
variable-width single-shot pulse generator modes. When in either of these modes, the
value in PREL1 is loaded into the counter on the first falling edge of the counter clock after
the counter is enabled. After time-out, the value in PREL2 is loaded into the counter. This
register can be read and written when the timer module is enabled (i.e., the STP bit in the
MCR is cleared). However, a write to this register must be completed before time-out for
the new value to be reliably loaded into the counter.
PREL2
$60E
15
14
13
12
11
10
9876543210
PR2-15
PR2-14
PR2-13
PR2-12
PR2-11
PR2-10
PR2-9
PR2-8
PR2-7
PR2-6
PR2-5
PR2-4
PR2-3
PR2-2
PR2-1
PR2-0
RESET:
1111111111111111
Supervisor/User
8.4.8 Compare Register (COM)
The COM can be used in any mode. When the 16-bit counter reaches the value in the
COM, the TC and COM bits in the SR are set. In the input capture/output compare mode,
a compare event can be programmed to set, clear, or toggle TOUT. The register can be
read and written when the timer module is enabled (i.e., the STP bit in the MCR is
cleared).
COM
$610
15
14
13
12
11
10
9876543210
COM15 COM14 COM13 COM12 COM11 COM10
COM9
COM8
COM7
COM6
COM5
COM4
COM3
COM2
COM1
COM0
RESET:
0000000000000000
Supervisor/User
The COM can be used to produce an interrupt when the SR TC bit has been enabled to
produce an interrupt and the counter counts down to a preselected value. The COM can
also be used to indicate that the timer is approaching time-out.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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