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ADSP-BF537 Blackfin Processor Hardware Reference
15-17
General-Purpose Timers
If enabled, a timer interrupt is generated at the end of each period. An
interrupt service routine (ISR) must clear the interrupt latch bit (
TIMILx
)
and might alter period and/or width values. In pulse width modulation
(PWM) applications, the software needs to update period and pulse width
values while the timer is running. When software updates either period or
pulse width registers, the new values are held by special buffer registers
until the period expires. Then the new period and pulse width values
become active simultaneously. Reads from timer period and timer pulse
width registers return the old values until the period expires.
The
TOVF_ERRx
status bit signifies an error condition in
PWM_OUT
mode.
The
TOVF_ERRx
bit is set if
TIMERx_PERIOD = 0
or
TIMERx_PERIOD = 1
at
startup, or when the timer counter register rolls over. It is also set if the
timer pulse width register is greater than or equal to the timer period reg-
ister by the time the counter rolls over. The
ERR_TYP
bits are set when the
TOVF_ERRx
bit is set.
Although the hardware reports an error if the
TIMERx_WIDTH
value equals
the
TIMERx_PERIOD
value, this is still a valid operation to implement PWM
patterns with 100% duty cycle. If doing so, software must generally ignore
Figure 15-6. Timer Enable Timing
SCLK
TIMERx_PERIOD
4
4
4
EXAMPLE TIMER ENABLE TIMING (PWM_OUT MODE, PERIOD_CNT = 1)
1
1
1
X
4
1
2
3
1
2
3
TIMERx_WIDTH
TIMERx_COUNTER
TIMENx
TRUNx
TMRx, PULSE_HI = 0
TMRx, PULSE_HI = 1
W1S TO
TIMER_ENABLE
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...