DS3181 Datasheet, PDF (181/389 Pages) Maxim Integrated Products – Single/Dual/Triple/Quad ATM/Packet PHYs with Built-In LIU

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automatically, it is set to one when at least one parity error has been detected on the receive side during the
previous frame.
The payload type is sourced from a register. The three register bits are inserted in the third, fourth, and fifth bits of
the MA byte in each frame.
The multiframe indicator and timing marker bits can be directly inserted from a 3-bit register or generated from a 4-
bit register. The multiframe indicator and timing marker insertion type is programmable (direct or generated). When
the multiframe indicator and timing marker bits are directly inserted, the three register bits are inserted in the last
three bits of the MA byte in each frame. When the multiframe indicator and timing marker bits are generated, the
four timing source indicator bits are transferred in a four-frame multiframe, MSB first. The multiframe indicator bits
(sixth and seventh bits of the MA byte) identify the phase of the multiframe (00, 01, 10, or 11), and the timing
marker bit (eighth bit of the MA byte) contains the corresponding timing source indicator bit (TMABR register bits
TTI3, TTI2, TTI1, or TTI0 respectively). Note: The initial phase of the multiframe is arbitrarily chosen.
The first byte in the fifth row of the frame is overwritten with the NR byte which can be sourced from a register, from
the transmit FEAC controller, or from the transmit HDLC controller. The NR byte source is programmable (register,
FEAC, or HDLC). Note: The HDLC controller will source eight bits per frame period regardless of whether the NR
byte only, GC byte only, or both are programmed to be sourced from the HDLC controller.
The first byte in the sixth row of the frame is overwritten with the GC byte which can be sourced from a register or
from the transmit HDLC controller. The GC byte source is programmable (register or HDLC).
Once all of the E3 overhead bytes have been overwritten, the data stream is passed on to error insertion. If frame
generation is disabled, the incoming E3 signal is passed on directly to error insertion. Frame generation is
programmable (on or off).
10.10.8.3 Transmit G.832 E3 Error Insertion
Error insertion inserts various types of errors into the different E3 overhead bytes. The types of errors that can be
inserted are framing errors, BIP-8 parity errors, and Remote Error Indication (REI) errors.
The type of framing error(s) inserted is programmable (errored frame alignment bit or errored frame alignment
word). A frame alignment bit error is a single bit error in the frame alignment word (FA1 or FA2). A frame alignment
word error is an error in all 16 bits of the frame alignment word (the values 09h and D7h are inserted in the FA1
and FA2 bytes, respectively). Framing error(s) can be inserted one error at a time, or four consecutive frames. The
framing error insertion mode (single or four) is programmable.
The type of BIP-8 error(s) inserted is programmable (errored BIP-8 bit or errored BIP-8 byte). An errored BIP-8 bit
is inverting a single bit error in the EM byte. An errored BIP-8 byte is inverting all eight bits in the EM byte. BIP-8
error(s) can be inserted one error at a time, or continuously. The BIP-8 error insertion mode (single or continuous)
is programmable.
An REI error is generated by forcing the second bit of the MA byte to a one. REI error(s) can be inserted one error
at a time, or continuously. The REI error insertion mode (single or continuous) is programmable.
Each error type (framing, BIP-8, or REI) has a separate enable. Continuous error insertion mode inserts errors at
every opportunity. Single error insertion mode inserts an error at the next opportunity when requested. The framing
multi-error insertion mode inserts the indicated number of errors at the next opportunities when requested. I.e., a
single request will cause multiple errors to be inserted. The requests can be initiated by a register bit (TSEI) or by
the manual error insertion input (TMEI). The error insertion request source (register or input) is programmable. The
insertion of each particular error type is individually enabled. Once all error insertion has been performed, the data
stream is passed on to overhead insertion.
10.10.8.4 Transmit G.832 E3 Overhead Insertion
Overhead insertion can insert any (or all) of the E3 overhead bytes into the E3 frame. The E3 overhead bytes FA1,
FA2, EM, TR, MA, NR, and GC can be sourced from the transmit overhead interface (TOHCLK, TOH, TOHEN, and
TOHSOF). The EM byte is sourced as an error mask (modulo 2 addition of the input EM byte and the generated
EM byte). The E3 overhead insertion is fully controlled by the transmit overhead interface. If the transmit overhead
data enable signal (TOHEN) is driven high, then the bit on the transmit overhead signal (TOH) is inserted into the
output data stream. Insertion of bits using the TOH signal overwrites internal overhead insertion.
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