Description of Operation
15-6
ADSP-BF537 Blackfin Processor Hardware Reference
Clock and capture input pins are sampled every
SCLK
cycle. The duration
of every low or high state must be one
SCLK
minimum. The maximum
allowed frequency of timer input signals is
SCLK
/
2
, therefore.
Internal Interface
Timer registers are always accessed by the core through the 16-bit PAB
bus. Hardware ensures that all read and write operations from and to
32-bit timer registers are atomic.
Every timer has its dedicated interrupt request output that connects to the
SIC controller. In total the module has eight interrupt outputs, therefore.
Description of Operation
The core of every timer is a 32-bit counter, that can be interrogated
through the read-only
TIMERx_COUNTER
register. Depending on operation
mode, the counter is reset to either 0x0000 0000 or 0x0000 0001 when
the timer is enabled. The counter always counts upward. Usually, it is
clocked by
SCLK
. In PWM mode it can be clocked by the alternate clock
input
TACLKx
or the common timer clock input
TMRCLK
alternatively. In
counter mode, the counter is clocked by edges on the
TMRx
input. The sig-
nificant edge is programmable.
After 2
32
-1 clocks the counter overflows. In case, this is reported by the
overflow/error bit
TOVF_ERRx
in the global timer status (
TIMER_STATUS
)
register. In PWM and counter mode the counter is reset by hardware
when its content reaches the values stored in the
TIMERx_PERIOD
register.
In capture mode the counter is reset by leading edges on the input pin
TMRx
or
TACIx
. If enabled, these events cause the interrupt latch
TIMILx
in
the
TIMER_STATUS
registers to be set and issue a system interrupt request.
The
TOVF_ERRx
and
TIMILx
latches are sticky and should be cleared by
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 ...