AP512 ACROPACK
USER
’S MANUAL
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mode if any interrupts are pending.
5
1
0 = Disable the Receive Xoff Interrupt 1 = Enable the
Receive Xoff Interrupt
When software flow control in enabled, and one or two
sequential receive data characters match the
preprogrammed Xoff 1-2 values an interrupt will be issued.
6
1
0 = Disable RTS Interrupt 1 = Enable RTS Interrupt.
This Interrupt is generated when the RTS pin transitions
from a logic 0 to a logic 1. RTS is not output by this
module. Instead RTS is used to enable the transmitter of
the port. This interrupt should always be disabled.
7
1
0 = Disable CTS Interrupt 1 = Enable CTS Interrupt.
This interrupt will be issued when the CTS pin transitions
from a logic 0 to a logic 1. Since CTS is not used on this
module, this interrupt should always be disabled.
Bits 4 to 7 are only programmable when the EFR
bit 4 is set to “1”. A power
-
up or system reset sets all IER bits to 0 (bits 7-0 forced low).
3.2.6 ISR - Interrupt Status Register (READ Only)
The Interrupt Status Register is used to indicate that a prioritized interrupt is
pending and the type of interrupt that is pending. Six levels of prioritized
interrupts are provided to minimize software interaction. Performing a read
cycle on the ISR will provide the user with the highest pending interrupt
level to be serviced. No other interrupts are acknowledged until the
pending interrupt is serviced. Whenever the interrupt status register is
read, the interrupt status is cleared. Note, only the current pending
interrupt is cleared by the read. A lower level interrupt may be seen after
re-reading the interrupt status bits.
The following interrupt source table shows the data values (bit 0-5) for the
six prioritized interrupt levels and the interrupt sources associated with each
of these interrupts.
Table 3.7 Interrupt source
PRIORITY
LEVEL
ISR BITS
Bit5 to Bit0
Source of the Interrupt
1
000110
Receiver Line Status (see LSR bits 1-4)
2
000100
Received Data Ready or Trigger Level
reached.
2
001100
Receive Data Time Out.