ADSP-214xx SHARC Processor Hardware Reference
16-11
Peripheral Timers
To control the assertion sense of the
TIMERx_O
signal, the
PULSE
bit in the
corresponding
TMxCTL
register is either cleared (causes a low assertion
level) or set (causes a high assertion level).
When enabled, a timer interrupt is generated at the end of each period. An
ISR must clear the interrupt latch bit
TIMxIRQ
and might alter period
and/or width values. In pulse width modulation applications, the program
can update the period and pulse width values while the timer is running.
When a program updates the timer configuration, the
TMxW
register
must always be written to last, even if it is necessary to update only
one of the registers. When the
TMxW
value is not subject to change,
the ISR reads the current value of the
TMxW
register and rewrite it
again. On the next counter reload, all of the timer control registers
are read by the timer.
To generate the maximum frequency on the
TIMERx_O
output signal, set
the period value to two and the pulse width to one. This makes the
TIMERx
signal toggle every 2
PCLK
clock cycles as shown in
PCLK
= 133 MHz:
Maximum period = 2
×
(2
31
– 1)
×
7.5 ns = 32 seconds.
If your application requires a more sophisticated PWM output
generator, refer to
Chapter 7, Pulse Width Modulation
.
Single-Pulse Generation
If the
PRDCNT
bit is cleared, the
PWM_OUT
mode generates a single pulse on
the
TIMERx_O
signal. This mode can also be used to implement a well
defined software delay that is often required by state machines. The pulse
width (= 2 ×
TMxW
) is defined by the width register and the period register
should be set to a value greater than the pulse width register.
At the end of the pulse, the interrupt latch bit (
TIMxIRQ
) is set and the
timer is stopped automatically. If the
PULSE
bit is set, an active high pulse
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Содержание SHARC ADSP-214 Series
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Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
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Страница 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...