參數(shù)資料
型號: CTMRM
英文描述: Configurable Timer Module Reference Manual
中文描述: 配置定時器模塊參考手冊
文件頁數(shù): 81/164頁
文件大小: 1148K
代理商: CTMRM
CTM
REFERENCE
MOTOROLA
8-11
DOUBLE ACTION SUBMODULE (DASM)
For More Information On This Product,
Go to: www.freescale.com
8
Warning:
There is no hardware protection to disable comparator B while comparator A is enabled.
It is the user’s responsibility to load data registers A and B with the values needed to
produce the desired PWM output pulse.
Note:
If both channels are loaded with the same value they will try to force different levels on
the output flip-flop. Hardware protection circuitry ensures that no contention occurs and
the output flip-flop provides a logic zero level output.
Figure 8-7 provides an example of how the DASM can be used for pulse width modulation.
To generate PWM output pulses of different frequencies, the 16-bit comparator can have some of
its bits masked. This is controlled by bits MODE2, MODE1 and MODE0. The frequency of the
PWM output (f
PWM
) is given by the following equation (assuming the DASM is connected to a free
running counter):
[1]
where N
CPSM
is the overall CPSM clock divide ratio (
÷
2 to
÷
512 or
÷
3 to
÷
768) and N
DASM
is the
DASM divide ratio.
A few examples of frequencies and resolutions that can be obtained are shown in Table 8-2.
Figure 8-7
DASM output pulse width modulation example
Time base bus
$1000
$1100
$0000
$1000
$1500
$1700
FLAG bit
DASMA value
1
B1 value
1
B2 value
2
$xxxx
$1500
$1500
$1700
$1700
$1000
$1000
$1000
$1000
$1000
$xxxx
$xxxx
$1500
$1700
$1700
PWMoutput
EDPOL = 0
FLAG reset
by software
FLAG reset
by software
B2 comparison
matches
Write
A comparison
matches
B2 comparison
matches
B1 = $1700
Write
B1 = $1500
A comparison
matches
$1000
$1700
$1700
1. These values are accessible to the software.
2. These values are internal and are not accessible.
Notes:
f
PWM
f
CPSM
N
DASM
N
=
F
.
Freescale Semiconductor, Inc.
相關(guān)PDF資料
PDF描述
CTN368 TRANSISTOR | BJT | NPN | 20V V(BR)CEO | 1A I(C) | TO-237AA
CTN369 TRANSISTOR | BJT | PNP | 20V V(BR)CEO | 500MA I(C) | TO-237
CTO1065 Analog IC
CTS0003IB Analog IC
CTS0024GB Voltage-Feedback Operational Amplifier
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
CTMT001A 制造商:Richco 功能描述:CABLE TIE SCREW MOUNT:NYL NATURA
CTMT002A 制造商:Richco 功能描述:CABLE TIE SCREW MOUNT:NYL NATURA
CTMT003A 制造商:Richco 功能描述:CABLE TIE SCREW MOUNT:NYL NATURA
CTMT004A 制造商:Richco 功能描述:CABLE TIE SCREW MOUNT:NYL NATURA
CT-MVS.12P 制造商:ABB Control 功能描述:Multi-function Timer 1C/O