Functional Description
7-10
ADSP-214xx SHARC Processor Hardware Reference
The range of T
AL
is:
and the corresponding duty cycles are:
The minimum permissible value of T
AH
and T
AL
is zero, which corre-
sponds to a 0% duty cycle, and the maximum value is T
S
, the PWM
switching period, which corresponds to a 100% duty cycle. Negative val-
ues are not permitted.
The output signals from the timing unit for operation in double update
mode are shown in
. This illustrates a general case where the
switching frequency, dead time, and duty cycle are all changed in the sec-
ond half of the PWM period. The same value for any or all of these
quantities can be used in both halves of the PWM cycle. However, there is
no guarantee that a symmetrical PWM signal will be produced by the tim-
ing unit in this double update mode. Additionally,
the dead time is inserted into the PWM signals in the same way as in sin-
gle update mode.
In general, the on-times (active low) of the PWM signals over the full
PWM period in double update mode can be defined as:
0
2
–
PWMPERIOD
t
PCLK
]
×
×
[
d
AH
t
AH
T
S
--------
1
2
---
PWMCHA PWMDT
–
PWMPERIOD
--------------------------------------------------------------------
+
=
=
d
AL
t
AL
T
S
-------
1
2
---
PWMCHA PWMDT
–
PWMPERIOD
--------------------------------------------------------------------
+
=
=
T
S
PWMPERIOD
1
PWMPERIOD
2
+
(
)
t
PCLK
×
=
T
A
L
PWMPERIOD
1
2
-----------------------------------------
PWMPERIOD
2
2
-----------------------------------------
PWMCHA
1
–
PWMCHA
2
–
PWMDT
1
PWMDT
2
–
–
+
t
PCLK
×
=
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Содержание SHARC ADSP-214 Series
Страница 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
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...
Страница 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
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...