XRT79L71_1 Datasheet, PDF (164/434 Pages) Exar Corporation – 1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC -

XRT79L71
1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - REGISTER/MAP DESCRIPTION
REV. 1.0.0
BIT NUMBER
NAME
2
F Bit Mask [2]/NA Bit
(C12)
TYPE
R/W
DESCRIPTION
Transmit F-Bit Error - Bit 3/NA Bit (C12):
The exact function of this register bit depends upon the following
parameters.
• Whether the XRT79L71 has been configured to operate in the
Clear-Channel Framer Mode, or not.
• Whether Bit 7 (TxOHSrc), within the Test Register (Address =
0x110C) is set to "1" or "0".
If the XRT79L71 is NOT configured to operate in the Clear-
Channel Framer Mode, OR if TxOHSrc = "0" - Transmit F-Bit
Error - Bit 3:
This READ/WRITE bit-field permits the user to configure the
Transmit DS3 Framer block to transmit DS3 frames with an
erred F bit.
This F-bit corresponds with the 3rd F-bit, within a given outbound
DS3 frame. The Transmit DS3 Framer block will perform an
XOR operation with the contents of this bit-field and value of the
3rd F-bit. The results of this calculation will be written back into
the 3rd F-bit position, within each outbound DS3 frame.
The user should set this bit-field to "0" for normal (e.g., un-erred)
operation.
If the XRT79L71 is configured to operate in the Clear-Chan-
nel Framer Mode, AND if TxOHSrc = "1" - Insert Enable for
NA or C12 bit:
This READ/WRITE bit-field permits the user to configure the
Transmit Payload Data Input Interface block to externally accept
an overhead bit and insert it into the NA (or C12) bit-field, within
the outbound DS3 data-stream.
0 - Configures the Transmit Direction circuitry to externally
accept and insert data into this overhead bit-field.
1- Configures the Transmit Direction circuitry to NOT externally
accept and insert data into this overhead bit-field.
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