PM7347 datasheet(75/341 Pages) PMC

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S/UNI®-JET Data Sheet

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Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use

Document ID: PMC-1990267, Issue 3

• Maintaining the transmit FIFO read and write pointers.

• Detecting a FIFO overrun condition.

The FIFO interface is “UTOPIA Level 2” compliant and accepts a write clock (TFCLK), a write

enable signal (TENB), the start of a cell (TSOC) indication, and the parity bit (TPRTY), and the

ATM device address (TADR[4:0]) when data is written to the transmit FIFO (using the rising

edges of TFCLK). The interface provides the transmit cell available status (TCA and

DTCA[4:1]), which can transition from "available" to "unavailable" when the transmit FIFO is

near full (when TCALEVEL0 is logic zero) or when the FIFO is full (when TCALEVEL0 is logic

one) and can accept no more writes. To reduce FIFO latency, the FIFO depth at which TCA and

DTCA[x] indicates "full" can be set to one, two, three, or four cells by the FIFODP[1:0] bits of

TXCP-50 Configuration 2 Register. If the programmed depth is less than four, more than one cell

may be written after TCA or DTCA[x] is asserted as the TXCP-50 still allows four cells to be

stored in its FIFO. This interface also indicates FIFO overruns via a maskable interrupt and

automatically transmits idle cells until a full cell is available to be transmitted.

10.21 TTB Trail Trace Buffer

The Trail Trace Buffer (TTB) extracts and sources the trail trace message carried in the TR byte

of the G.832 E3 stream. The message is used by the OS to prevent delivery of traffic from the

wrong source and is 16 bytes in length.

The 16-byte message is framed by the PTI Multiframe Alignment Signal (TMFAS = 'b10000000

00000000). One bit of the TMFAS is placed in the most significant bit of each message byte. In

the receive direction, the trail trace message is extracted from the serial overhead stream output

by the E3-FRMR. The extracted message is stored in the internal RAM for review by an external

microprocessor. By default, the TTB will write the byte of a 16-byte message with its most

significant bit set high to the first location in the RAM. The extracted trail trace message is

checked for consistency between consecutive multiframes. A message received unchanged three

or five times (programmable) is accepted for comparison with the copy previously written into

the internal RAM by the external microprocessor. Alarms are raised to indicate reception of

unstable and mismatched messages. In the transmit direction, the TTB sources the trail trace

message from the internal RAM for insertion into the TR byte by the E3-TRAN.

The TTB also extracts the Payload Type label carried in the MA byte of the G.832 E3 stream. The

label is used to ensure that the adaptation function at the trail termination sink is compatible with

the adaptation function at the trail termination source. The Payload Type label is check for

consistency between consecutive multiframes. A Payload Type label received unchanged for five

frames is accepted for comparison with the copy previously written into the TTB by the external

microprocessor. Alarms are raised to indicate reception of unstable and mismatched Payload Type

label bits.

10.22 JTAG Test Access Port

The JTAG Test Access Port block provides JTAG support for boundary scan. The standard JTAG

EXTEST, SAMPLE, BYPASS, IDCODE, and STCTEST instructions are supported.

PM7347 Datasheet(PDF) 75 Page - PMC-Sierra, Inc

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