
XRT79L71
PRELIMINARY
133
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
The user can do this by writing a "1" into Bit 1 (Enable Interrupt Auto-Clear) within the Operating Mode
Register - Byte 2, as depicted below.
This action will prevent the Transmit LAPD Controller from generating its own one-second interrupts.
2.
Enable the One-Second Interrupt
This can be done by writing a "1" into Bit 0 (One Second Interrupt Enable) within the Block Interrupt Enable
Register, as depicted below.
3.
Write the new message into the Transmit LAPD Message buffer immediately after the occurrence
of the One-Second interrupt.
By timing the writes to the Transmit LAPD Message buffer to occur immediately after the occurrence of the
One-Second interrupt, the user avoids conflicting with the one-second transmissions of the LAPD Message
frame, and will transmit the correct messages to the remote LAPD Receiver.
4.2.4.3
Transmit LAPD Controller Block Interrupt
4.2.5
TRANSMIT DS3 FRAMER BLOCK
The Transmit DS3 Framer block is the fifth functional block within the Transmit Direction of the XRT79L71 that
we will discuss for Clear-Channel Framer Applications. Figure 58 presents an illustration of the Transmit
Direction circuitry whenever the XRT79L71 has been configured to operate in the DS3 Clear-Channel Framer
Mode, with the Transmit DS3/E3 Framer block highlighted.
Operation Control Register - Byte 2 (Address = 0x0101)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
UNUSED
INTERRUPT
WC/INT*
ENABLE
INTERRUPT
AUTO-CLEAR
INTERRUPT
ENABLE
R/O
R/W
0
1
0
Block Interrupt Enable Register (Address = 0x1104)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Receive DS3/E3
Framer Block
Interrupt Enable
Receive PLCP
Processor Block
Interrupt Enable
Unused
Transmit DS3/
E3 Framer
Block Interrupt
Enable
One Second
Interrupt
R/W
R/O
R/W
0
1