21
x r
PRELIMINARY
E3 UNI FOR ATM
XRT7234
REV. P1.0.0
24
32
CSB*
I
Chip Select Input:
This active-low input signal selects the Microprocessor
Interface Section of the UNI device and enables Read/Write operations
between the “l(fā)ocal” microprocessor and the UNI on-chip registers and
RAM locations.
25
33
RDB_DS
I
Read Data Strobe (Intel Mode):
If the microprocessor interface is oper-
ating in the Intel Mode, then this input will function as the RD* (READ
STROBE) input signal from the local
μ
P
. Once this active-low signal is
asserted, then the UNI will place the contents of the addressed registers
(within the UNI) on the Microprocessor Data Bus (D[15:0]). When this
signal is negated, the Data Bus will be tri-stated.
Data Strobe (Motorola Mode):
If the microprocessor interface is operating
in the Motorola mode, then this pin will function as the active-low Data
Strobe signal.
34
RxGFC
O
Receive GFC Nibble Field Serial Output pin:
This pin, along with the
RxGFCClk and the RxGFCMSB pins form the “Receive GFC Nibble-Field”
serial output port. This pin will serially output the contents of the GFC
Nibble field of each valid cell that is processed through the Receive Cell
Processor. This data is serially clocked out of this pin on the rising edge
of the RxGFCClk signal. The Most Significant Bit (MSB) of each GFC
value is designated by a pulse at the RxGFCMSB output pin.
Notes:
1. The GFC Nibble Field Serial Output port is only available for the 160 pin
packaged device.
2. The “Receive GFC Nibble-Field” serial output port will only output the
GFC Nibble-field values of “valid” cells; not Idle cells.
26
35
WRB_RW
I
Write Data Strobe (Intel Mode):
If the microprocessor interface is operating
in the Intel Mode, then this active-low input pin functions as the WR*
(Write Strobe) input signal from the
μ
P
. Once this active-low signal is
asserted, then the UNI will latch the contents of the
μ
P
Data Bus, into
the addressed register (or RAM location) within the UNI IC.
R/W Input Pin (Motorola Mode):
When the Microprocessor Interface
Section is operating in the “Motorola Mode”, then this pin is functionally
equivalent to the “R/W*” pin. In the Motorola Mode, a “READ” operation
occurs if this pin is at a logic “1”. Similarly, a WRITE operation occurs if
this pin is at a logic “0”.
36
NC
****
Not Bonded Out
27
37
A8
I
Address Bus Input (Microprocessor Interface—MSB (Most Significant Bit):
This input pin, along with inputs A0–A7 are used to select the on-chip
UNI register and RAM space for READ/WRITE operations with the
“l(fā)ocal” microprocessor.
38
NC
****
Not Bonded Out
PIN DESCRIPTION (CONTINUED)
Pin
No.
100 Pin Package
Pin No. 160
PinPackage
Symbol
Type
Description