ADSP-BF535 Blackfin Processor Hardware Reference
16-13
Timers
Timer Modes
The
TMRx
pins function as outputs in PWM_OUT mode and as inputs in
WDTH_CAP and EXT_CLK modes. The timer mode is determined by
the value of the
MODE_FIELD
bits in the
TIMERx_CONFIG
register.
Pulse Width Modulation Mode (PWM_OUT)
Setting the
MODE_FIELD
bits to 01 in
TIMERx_CONFIG
enables PWM Output
mode (PWM_OUT). In PWM_OUT, the timer
TMRx
pin is an output.
In PWM_OUT mode, the
TMRx
pin is always driven low when the
timer is disabled, regardless of the state of the
PULSE_HI
bit. When
the timer is running, however, the
TMRx
pin polarity corresponds to
the
PULSE_HI
bit setting.
The timer is clocked internally by
SCLK
. Depending on the state of the
PERIOD_CNT
bit in
TIMERx_CONFIG
, PWM_OUT either generates pulse
width modulation waveforms or generates a single pulse on the
TMRx
pin.
When the timer is enabled, the timer checks the period and width values
for validity (independent of
PERIOD_CNT
) and does
not
start to count when
any of these invalid conditions is true:
• Width = 0
• Period value is lower than width value
• Width = period
The timer module tests these conditions on writes to the
TIMERx_WIDTH_LO
register. Before writing to
TIMERx_WIDTH_LO
, make sure that the
TIMERx_WIDTH_HI
and the
TIMERx_PERIOD
are set accordingly. On invalid
conditions, the timer sets both the
IRQx
and the
OVF_ERRx
bits in
TIMERx_STATUS
after two
SCLK
cycles. The Timer Counter register is not
altered. Note that after reset, the timer registers are all 0.
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...