ADSP-BF537 Blackfin Processor Hardware Reference
16-3
Core Timer
When the timer is enabled by setting the
TMREN
bit in the core timer con-
trol register (
TCNTL
), the
TCOUNT
register is decremented once every time
the prescaler
TSCALE
expires, that is, every
TSCALE
+ 1 number of
CCLK
clock cycles. When the value of the
TCOUNT
register reaches 0, an interrupt
is generated and the
TINT
bit is set in the
TCNTL
register.
If the
TAUTORLD
bit in the
TCNTL
register is set, then the
TCOUNT
register is
reloaded with the contents of the
TPERIOD
register and the count begins
again. If the
TAUTORLD
bit is not set, the timer stops operation.
The core timer can be put into low power mode by clearing the
TMPWR
bit
in the
TCNTL
register. Before using the timer, set the
TMPWR
bit. This
restores clocks to the timer unit. When
TMPWR
is set, the core timer may
then be enabled by setting the
TMREN
bit in the
TCNTL
register.
a
Hardware behavior is undefined if
TMREN
is set when
TMPWR
=
0
.
Interrupt Processing
The core timer has its dedicated interrupt request signal which is of higher
priority than all other peripherals’ requests. The requests goes directly to
the Core Event Controller (CEC) and does not pass the System Interrupt
Controller (SIC). Therefore, the interrupt processing is also completely in
the
CCLK
domain.
L
Unlike requests from other Blackfin peripherals, the core interrupt
request is edge sensitive and cleared by hardware automatically as
soon as the interrupt serviced.
The
TINT
bit in the
TCNTL
register indicates that an interrupt has been gen-
erated. Note that this is not a W1C bit. Write a 0 to clear it. However, the
write is optional. It is not required to clear interrupt requests. The core
time module doesn’t provide any further interrupt enable bit. When the
timer is enabled, interrupts can be masked in the CEC controller.
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 ...