S/UNI®-JET Data Sheet
Released
Pin Name
Type
Pin
No.
Function
DTCA
Output
J17
The Direct Access Transmit Cell Available (DTCA) output
signals indicate when a cell is available in the transmit
FIFO.
When high, DTCA indicates that the corresponding
transmit FIFO is not full and a complete cell may be
written. DTCA can be configured to indicate either that
the corresponding transmit FIFO is near full and can
accept no more than four writes or that the
corresponding transmit FIFO is full. DTCA will thus
transition low on the rising edge of TFCLK which
samples Payload byte 43 (TCALEVEL0=0) or 47
(TCALEVEL0=1) for the 8-bit interface (ATM8=1), or the
rising edge of TFCLK which samples Payload word 19
(TCALEVEL0=0) or 23 (TCALEVEL0=1) for the 16-bit
interface (ATM8=0).
To reduce FIFO latency, the FIFO depth at which DTCA
indicates "full" can be set to one, two, three or four cells.
Note: Regardless of what fill level DTCA is set to indicate
"full" at, the transmit cell processor can store four
complete cells.
The polarity of DTCA (with respect to the description
above) is inverted when the TCAINV register bit is set to
logic one.
The DTCA outputs can be used to support Utopia Direct
Access mode.
RDAT[15]
RDAT[14]
RDAT[13]
RDAT[12]
RDAT[11]
RDAT[10]
RDAT[9]
RDAT[8]
RDAT[7]
RDAT[6]
RDAT[5]
RDAT[4]
RDAT[3]
RDAT[2]
RDAT[1]
RDAT[0]
Output
T20
T19
R17
T18
U20
U19
T17
U18
V17
U16
W17
Y17
V16
U15
W16
Y16
The Receive Cell Data Bus (RDAT[15:0]) bus carries the
ATM cell octets that are read from the receive ATM FIFO
selected by RADR[2:0]. RDAT[15:0] is tri-stated when
RENB is high. RDAT[15:0] is updated on the rising edge
of RFCLK.
The S/UNI-JET can be configured to operate with an 8-
bit wide or 16-bit wide ATM data interface via the ATM8
input pin. RDAT[15:8] will remain tri-stated if ATM8 is set
to logic one.
RDAT[15:0] is tri-stated when either the null-PHY
address (7H) or an address not matching the address
space set by PHY_ADR[2:0] is latched from the
RADR[2:0] inputs when RENB is high.
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990267, Issue 3
46
PMC [ PMC-SIERRA, INC ]
