Timer Modes
16-14
ADSP-BF535 Blackfin Processor Hardware Reference
If period and width values are valid after the timer is enabled, the Timer
Counter register is loaded with the value (0xFFFF FFFF – width). The
timer counts upward to 0xFFFF FFFE. The timer then reloads the Timer
Counter register with the value (0xFFFF FFFF – (period – width)) and
repeats.
Pulse Width Modulation (PWM) Waveform Generation
If the
PERIOD_CNT
bit in the
TIMERx_CONFIG
register is set, the internally
clocked timer generates rectangular signals with well-defined period and
duty cycle. This mode also generates periodic interrupts for real-time core
processing.
The Timer Period and Timer Width registers are programmed with the
values of the timer count period and the pulse-width-modulated output
pulse width.
When the timer is enabled in this mode, the
TMRx
pin is pulled to a deas-
serted state each time the pulse width expires and the pin is asserted again
when the period expires (or when the timer gets started).
To control the assertion sense of the
TMRx
pin, the
PULSE_HI
bit in the
TIMERx_CONFIG
register is used. For a low assertion level, clear this bit. For
a high assertion level, set this bit.
Writes to
TIMERx_PERIOD_HI
,
TIMERx_PERIOD_LO
, and
TIMERx_WIDTH_HI
do not become active until
TIMERx_WIDTH_LO
is
written. Therefore,
TIMERx_WIDTH_LO
must always be written after
changing
TIMERx_PERIOD
. When the
TIMERx_WIDTH_LO
value is not
subject to change, the ISR may read back the current value of
TIMERx_WIDTH_LO
and write it again.
Summary of Contents for ADSP-BF535 Blackfin
Page 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Page 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Page 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Page 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Page 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Page 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Page 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Page 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Page 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Page 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Page 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...