
ADSP-214xx SHARC Processor Hardware Reference
7-7
Pulse Width Modulation
PCLK
clock increments in a PWM period (edge aligned mode) or in a half
PWM period (center aligned mode) in half a PWM period.
Therefore, the PWM switching period, T
s
, can be written as:
T
s
= 2 × PWMTM × t
PCLK
(edge aligned)
T
s
= PWMTM × t
PCLK
(center aligned)
For example, for a 200 MHz
PCLK
and a desired PWM center aligned
switching frequency of 10 kHz (T
s
= 100
μ
s), the correct value to load
into the
PWMPERIODx
register is:
The largest value that can be written to the 16-bit
PWMPERIODx
register is
0xFFFF = 65,535 which corresponds to a minimum PWM switching fre-
quency of:
PWMPERIOD
values of 0 and 1 are not defined and should not be used
when the PWM outputs or PWM sync is enabled.
Duty Cycles
The two 16-bit read/write duty cycle registers,
PWMA
and
PWMB
, control the
duty cycles of the four PWM output signals on the PWM pins. The
two’s-complement integer value in the
PWMA
register controls the duty
cycle of the signals on the
PWM_AH
and
PWM_AL
. The two’s-complement
integer value in the
PWMB
register controls the duty cycle of the signals on
PWM_BH
and
PWM_BL
pins. The duty cycle registers are programmed in
two’s-complement integer counts of the fundamental time unit,
PCLK
, and
define the desired on-time of the high-side PWM signal produced by the
PWMPERIOD
200
10
6
×
2
10
×
10
3
×
------------------------------
10000
=
=
f
PWM
(
)
min
,
200
10
6
×
2
65535
×
--------------------------
1523
Hz
=
=
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Summary of Contents for SHARC ADSP-214 Series
Page 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Page 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...