Operation Modes
7-24
ADSP-214xx SHARC Processor Hardware Reference
in each half period (or 2 x
PCLK
for the full period). In double update
mode, improved accuracy is possible since different values of the duty
cycles registers are used to define the on times in both the first and second
halves of the PWM period. As a result, it is possible to adjust the on-time
over the whole period in increments of
PCLK
. This corresponds to an
effective PWM accuracy of
PCLK
in double update mode (or 10 ns for a
200 MHz clock). The achievable PWM switching frequency at a given
PWM accuracy is tabulated in
PCLK
= 200 MHz.
Synchronization of PWM Groups
The
PWMGCTL
register enables or disables the four PWM groups in any
combination. This provides synchronization across the four PWM groups.
The
PWM_SYNC_ENx
bits in this register can be used to start the counter
without enabling the outputs through
PWM_EN
. So when
PWM_ENx
is
asserted, the 4 PWM outputs are automatically synced to the initially pro-
grammed period. In most cases, all
SYNC
bits can be initialized to zero,
enabling the
PWM_ENx
bits of the four PWM groups at the same time syn-
chronizes the four groups.
Table 7-4. PWM Accuracy in Single- and Double Update Modes
Resolution (bits)
Single Update Mode PWM
Frequency (kHz)
Double Update Mode PWM Frequency
(kHz)
8
200 MHz ÷ 2
×
2
8
= 390.63
200 MHz ÷ 2
8
= 781.25
9
195.3
390.6
10
97.7
195.3
11
48.8
97.7
12
24.4
48.8
13
12.2
24.4
14
6.1
12.2
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Содержание SHARC ADSP-214 Series
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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...
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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...