XRT7250 Datasheet, PDF (350/463 Pages) Exar Corporation – DS3/E3 FRAMER IC

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XRT7250
DS3/E3 FRAMER IC
REV. 1.1.1
Writing a “1” into this bit-field enables the Receive
LAPD Message Interrupt. Conversely, writing a “0”
into this bit-field disables the Receive LAPD Message
Interrupt.
Servicing the Receive LAPD Message Interrupt
Whenever the XRT7250 Framer IC generates this in-
terrupt, it will do the following.
• It will assert the Interrupt Request output pin (INT),
by driving it “Low”.
• It will set Bit 0 (RxLAPD Interrupt Status), within the
Rx E3 LAPD Control register to “1”, as indicated
below.
RXE3 LAPD CONTROL REGISTER (ADDRESS = 0X18)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
RxLAPD
Enable
RxLAPD
RxLAPD
Interrupt Enable Interrupt Enable
RO
RO
RO
RO
RO
R/W
R/W
RUR
0
0
0
0
0
0
0
0
• It will write the contents of the newly Received
LAPD Message into the Receive LAPD Message
buffer (located at 0xDE through 0x135).
Whenever the Terminal Equipment encounters the
Receive LAPD Message Interrupt, then it should read
out the contents of the Receive LAPD Message buff-
er, and respond accordingly.
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