
Table 25-5: status Register Bits
Bit Name R/W/C Description
0 TO RC The TO (timeout) bit is set to 1 when the internal counter reaches zero.
Once set by a timeout event, the TO bit stays set until explicitly cleared by a
master peripheral. Write zero to the status register to clear the TO bit.
1 RUN R The RUN bit reads as 1 when the internal counter is running; otherwise this
bit reads as 0. The RUN bit is not changed by a write operation to the
status register.
control Register
The control register has four defined bits.
Table 25-6: control Register Bits
Bit Name R/W/C Description
0 ITO RW If the ITO bit is 1, the interval timer core generates an IRQ when the
status register’s TO bit is 1. When the ITO bit is 0, the timer does not
generate IRQs.
1 CONT RW The CONT (continuous) bit determines how the internal counter behaves
when it reaches zero. If the CONT bit is 1, the counter runs continuously
until it is stopped by the STOP bit. If CONT is 0, the counter stops after it
reaches zero. When the counter reaches zero, it reloads with the value
stored in the period registers, regardless of the CONT bit.
2 START
(1)
W Writing a 1 to the START bit starts the internal counter running
(counting down). The START bit is an event bit that enables the counter
when a write operation is performed. If the timer is stopped, writing a 1
to the START bit causes the timer to restart counting from the number
currently stored in its counter. If the timer is already running, writing a
1 to START has no effect. Writing 0 to the START bit has no effect.
3 STOP
(1)
W Writing a 1 to the STOP bit stops the internal counter. The STOP bit is an
event bit that causes the counter to stop when a write operation is
performed. If the timer is already stopped, writing a 1 to STOP has no
effect. Writing a 0 to the stop bit has no effect.
If the timer hardware is configured with Start/Stop control bits off,
writing the STOP bit has no effect.
Table 25-6 :
1. Writing 1 to both START and STOP bits simultaneously produces an undefined result.
UG-01085
2014.24.07
Register Map
25-7
Interval Timer Core
Altera Corporation
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