msx532 Fairchild Semiconductor, msx532 Datasheet - Page 3

• Manufacturer Part Number: msx532
• Description: 532 Port Digital Crosspoint Switch With Lvttl I/o S
• Manufacturer: Fairchild Semiconductor

Introduction
Input and Output Buffers (I/O buffers)
Each signal in the switch matrix is connected to a program-
mable I/O buffer, which is independently configured
through either the RapidConfigure or JTAG Interface. The
I/O buffer attributes include its signal direction (input, out-
put or bi-directional) and data flow mode (flow-through or
registered). The signal can also be inverted at the output.
Trickle current source (normally 15 A) on the pin side and
I/O Port Function Mode
The following legend describes the various modes of the
Input or Output Ports and the specification used by the
Fairchild Development System Software for bitstream gen-
eration.
Legend:
Ax
Px
IE
OE
CLK
Switch Matrix Signal
I/O Port Signal
Input Enable
Output Enable (Active LOW)
Clock
(Continued)
Sources
Sources
CLK
CLK
Neighbor
Neighbor
OE
Next
Next
Port
IE
I/O
{
V
{
{
{
V
DD
SS
FIGURE 3. MSX I/O Buffer Block Diagram
CLK_OUT
CLK_IN
3
array side for each I/O Port and control pin is used to pull
unused or non-driven circuits to a stable HIGH level. Figure
3 shows a basic block diagram of an I/O buffer with the
sources for the three control signals (IE, OE and CLK). For
any given port number, these three control signals can be
selected from one of two sources. The control signals are
explained in more detail in the following section.
Next-Neighbor Clocking
Included among the clocking options in MSX532 is the abil-
ity to use an adjacent port as a clock source. This is
referred to as a Next-Neighbor Clock. In the MSX532, Port
0 can be clocked by Port 1, which can be clocked by Port 2,
which can be clocked by Port 3, etc. In turn, Port 531 can
be clocked by Port 0. Since each I/O buffer can be pro-
grammed as an input or an output (among other options)
there are four ways to utilize the next neighbor clock
option.
BR
OUT
IN
Switch
Matrix
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