
MOTOROLA
8-12
CTM
REFERENCE
DOUBLE ACTION SUBMODULE (DASM)
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8
When using 16 bits of resolution on the comparator (MODE[2:0] = 000), the output can vary from
a 0% duty cycle up to a duty cycle of 65535/65536. In this case it is not possible to have a 100%
duty cycle. In cases where 16-bit resolution is not needed, it is possible to have a duty cycle
ranging from 0% to 100%. Setting bit 15 of the value stored in register B to one results in the output
being ‘a(chǎn)lways set’. Clearing bit 15 (to zero) allows normal comparisons to occur and the normal
output waveform is obtained. Changes to and from the 100% duty cycle are done synchronously,
as are all other width changes.
In the OPWM mode, the WOR bit selects whether the output is totem pole driven or open-drain.
8.4
DASM interrupts
When the FLAG bit is set, an interrupt request is generated on one of eight levels as defined by
the interrupt level bits (IL[2:0]) in the DASMSIC register. If the interrupt level is set to zero,
interrupts are disabled.
(1) This table is valid only if the DASMis connected to a free-running counter.
Table 8-2
DASM PWM example output frequencies/resolutions at f
SYS
= 16 MHz
N
CPSM
N
DASM(1)
PWMoutput
frequency (Hz)
0.48
122.07
0.95
244.14
1.91
488.28
3.81
976.56
7.63
1953.13
15.26
3906.25
31.04
15625.00
244.14
62500.00
Resolution
(bits)
16
16
15
15
14
14
13
13
12
12
11
11
9
9
7
7
512
2
512
2
512
2
512
2
512
2
512
2
512
2
512
2
65536
65536
32768
32768
16384
16384
8192
8192
4096
4096
2048
2048
512
512
128
128
F
.
Freescale Semiconductor, Inc.