Texas Instruments TMS320DM355 사용자 설명서
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PRODUCT PREVIEW
5.16
Pulse Width Modulator (PWM)
5.16.1 PWM0/1/2/3 Electrical/Timing Data
PWM0/1/2/3
1
3
3
2
TMS320DM355
Digital Media System-on-Chip (DMSoC)
SPRS463A – SEPTEMBER 2007 – REVISED SEPTEMBER 2007
The DM355 contains 4 separate Pulse Width Modulator (PWM) modules. The pulse width modulator
(PWM) feature is very common in embedded systems. It provides a way to generate a pulse periodic
waveform for motor control or can act as a digital-to-analog converter with some external components.
This PWM peripheral is basically a timer with a period counter and a first-phase duration comparator,
where bit width of the period and first-phase duration are both programmable. The Pulse Width Modulator
(PWM) modules support the following features:
(PWM) feature is very common in embedded systems. It provides a way to generate a pulse periodic
waveform for motor control or can act as a digital-to-analog converter with some external components.
This PWM peripheral is basically a timer with a period counter and a first-phase duration comparator,
where bit width of the period and first-phase duration are both programmable. The Pulse Width Modulator
(PWM) modules support the following features:
•
32-bit period counter
•
32-bit first-phase duration counter
•
8-bit repeat count for one-shot operation. One-shot operation will produce N + 1 periods of the
waveform, where N is the repeat counter value.
waveform, where N is the repeat counter value.
•
Configurable to operate in either one-shot or continuous mode
•
Buffered period and first-phase duration registers
•
One-shot operation triggerable by hardware events with programmable edge transitions. (low-to-high or
high-to-low).
high-to-low).
•
One-shot operation triggerable by the CCD VSYNC output of the video processing subsystem (VPSS),
which allows any of the PWM instantiations to be used as a CCD timer. This allows the DM355 module
to support the functions provided by the DM320 CCD timer feature (generating strobe and shutter
signals).
which allows any of the PWM instantiations to be used as a CCD timer. This allows the DM355 module
to support the functions provided by the DM320 CCD timer feature (generating strobe and shutter
signals).
•
One-shot operation generates N+1 periods of waveform, N being the repeat count register value
•
Configurable PWM output pin inactive state
•
Interrupt and EDMA synchronization events
Table 5-46. Switching Characteristics Over Recommended Operating Conditions for PWM0/1/2/3
Outputs
(1)
(see
and
DM355
NO.
PARAMETER
UNIT
MIN
MAX
1
t
w(PWMH)
Pulse duration, PWMx high
P
ns
2
t
w(PWML)
Pulse duration, PWMx low
P
ns
3
t
t(PWM)
Transition time, PWMx
.05P
ns
4
t
d(CCDC-PWMV)
Delay time, CCDC(VD) trigger event to PWMx valid
10
ns
(1)
P = MXI1/CLKIN cycle time in ns. For example, when MXI1/CLKIN frequency is 24 MHz use P = 41.6 ns.
Figure 5-47. PWM Output Timing
Peripheral Information and Electrical Specifications
145