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MC68F375
CONFIGURABLE TIMER MODULE (CTM9)
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
13-37
13.5.5.2 DASMA — DASM Data Register A
DASMA is the data register associated with channel A; its use varies with the different
modes of operation:
In the DIS mode, DASMA can be accessed to prepare a value for a subsequent
mode selection.
In the IPWM mode, DASMA contains the captured value corresponding to the
trailing edge of the measured pulse.
In the IPM and IC modes, DASMA contains the captured value corresponding to
the most recently detected dedicated edge (rising or falling edge).
In the OCB and OCAB modes, DASMA is loaded with the value corresponding to
the leading edge of the pulse to be generated. Writing to DASMA in the OCB and
OCAB modes also enables the corresponding channel A comparator until the
next successful comparison.
In the OPWM mode, DASMA is loaded with the value corresponding to the lead-
ing edge of the PWM pulse to be generated.
4EDPOL
Edge polarity. In the DIS mode, this bit is not used; reading it returns the last value written.
In the IPWM mode, this bit is used to select the capture edge sensitivity of channels A and B.
0 = Channel A captures on a rising edge.
Channel B captures on a falling edge.
1 = Channel A captures on a falling edge.
Channel B captures on a rising edge.
In the IPM and IC modes, the EDPOL bit is used to select the input capture edge sensitivity of
channel A.
0 = Channel A captures on a rising edge.
1 = Channel A captures on a rising edge.
In the OCB, OCAB and OPWM modes, the EDPOL bit is used to select the voltage level on the
output pin.
0 = The output flip-flop logic level appears on the output pin: a compare on channel A sets the
output pin, a compare on channel B resets the output pin.
1 = The complement of the output flip-flop logic level appears on the output pin: a compare on
channel A resets the output pin; a compare on channel B sets the output pin.
3:0
MODE[3:0
]
Mode select. The four mode select bits select the mode of operation of the DASM. To avoid spu-
rious interrupts, it is recommended that DASM interrupts are disabled before changing the
operating mode.
DASM3A — DASM Data Register A
0xYF F21A
DASM4A
0xYF F222
DASM9A
0xYF F24A
DASM10A
0xYF F252
MSB
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
LSB
0
MSB
LSB
RESET:
0
Table 13-11 DASMSIC Bit Settings (Continued)
Bit(s)
Name
Description
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Freescale Semiconductor, Inc.
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