ADSP-BF537 Blackfin Processor Hardware Reference
15-13
General-Purpose Timers
Modes of Operation
The following sections provide a functional description of the gen-
eral-purpose timers in various operating modes.
Pulse Width Modulation (PWM_OUT) Mode
Use the
PWM_OUT
mode for PWM signal or single-pulse generation, for
interval timing or for periodic interrupt generation.
PWM_OUT
mode.
Setting the
TMODE
field to b#01 in the timer configuration
(
TIMERx_CONFIG
) register enables
PWM_OUT
mode. Here, the timer
TMRx
pin
is an output, but it can be disabled by setting the
OUT_DIS
bit in the timer
configuration register.
In
PWM_OUT
mode, the bits
PULSE_HI
,
PERIOD_CNT
,
IRQ_ENA
,
OUT_DIS
,
CLK_SEL
,
EMU_RUN
, and
TOGGLE_HI
enable orthogonal functionality. They
may be set individually or in any combination, although some combina-
tions are not useful (such as
TOGGLE_HI = 1
with
OUT_DIS = 1
or
PERIOD_CNT = 0
).
Once a timer has been enabled, the timer counter register is loaded with a
starting value. If
CLK_SEL = 0
, the timer counter starts at 0x1. If
CLK_SEL = 1
, it is reset to 0x0 as in
EXT_CLK
mode. The timer counts
upward to the value of the timer period register. For either setting of
CLK_SEL
, when the timer counter equals the timer period, the timer
counter is reset to 0x1 on the next clock.
In
PWM_OUT
mode, the
PERIOD_CNT
bit controls whether the timer generates
one pulse or many pulses. When
PERIOD_CNT
is cleared (
PWM_OUT
single
pulse mode), the timer uses the
TIMERx_WIDTH
register, generates one
asserting and one deasserting edge, then generates an interrupt (if enabled)
and stops. When
PERIOD_CNT
is set (
PWM_OUT
continuous pulse mode), the
timer uses both the
TIMERx_PERIOD
and
TIMERx_WIDTH
registers and
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...