ADSP-BF50x Blackfin Processor Hardware Reference
10-21
General-Purpose Timers
Externally Clocked PWM_OUT
By default, the timer is clocked internally by
SCLK
. Alternatively, if the
CLK_SEL
bit in the
TIMER_CONFIG
register is set, the timer is clocked by
PWM_CLK
. The
PWM_CLK
is normally input from the
TACLK
pin, but may be
taken from the common
TMRCLK
pin regardless of whether the timers are
configured to work with the PPI. Different timers may receive different
signals on their
PWM_CLK
inputs, depending on configuration. As selected
by the
PERIOD_CNT
bit, the
PWM_OUT
mode either generates pulse width
modulation waveforms or generates a single pulse with pulse width
defined by the
TIMER_WIDTH
register.
When
CLK_SEL
is set, the counter resets to 0x0 at startup and increments
on each rising edge of
PWM_CLK
. The
TMR
pin transitions on rising edges of
PWM_CLK
. There is no way to select the falling edges of
PWM_CLK
. In this
mode, the
PULSE_HI
bit controls only the polarity of the pulses produced.
The timer interrupt may occur slightly before the corresponding edge on
the
TMR
pin (the interrupt occurs on an
SCLK
edge, the pin transitions on a
later
PWM_CLK
edge). It is still safe to program new period and pulse width
values as soon as the interrupt occurs. After a period expires, the counter
rolls over to a value of 0x1.
The
PWM_CLK
clock waveform is not required to have a 50% duty cycle, but
the minimum
PWM_CLK
clock low time is one
SCLK
period, and the mini-
mum
PWM_CLK
clock high time is one
SCLK
period. This implies the
maximum
PWM_CLK
clock frequency is
SCLK
/2.
The alternate timer clock inputs (
TACLK
) are enabled when a timer is in
PWM_OUT
mode with
CLK_SEL
= 1 and
TIN_SEL
= 0, without regard to the
content of the multiplexer control and function enable registers.
Using PWM_OUT Mode With the PPI
Some timers may be used to generate frame sync signals for certain PPI
modes. For detailed instructions on how to configure the timers for use
Содержание EZ-KIT Lite ADSP-BF506F
Страница 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 132: ...Unique Information for the ADSP BF50x Processor 4 22 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 342: ...Unique Information for the ADSP BF50x Processor 7 106 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 484: ...Unique Information for the ADSP BF50x Processor 10 60 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 493: ...ADSP BF50x Blackfin Processor Hardware Reference 11 9 Core Timer Unique Information for the ADSP BF50x Processor None ...
Страница 494: ...Unique Information for the ADSP BF50x Processor 11 10 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 506: ...Unique Information for the ADSP BF50x Processor 12 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 544: ...Unique Information for the ADSP BF50x Processor 13 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 712: ...Unique Information for the ADSP BF50x Processor 16 62 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 972: ...Unique Information for the ADSP BF50x Processor 20 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...