HA457 Datasheet, PDF (8/14 Pages) Intersil Corporation – 95MHz, Low Power, AV = 2, 8 x 8 Video Crosspoint Switch

HA457
32-Bit Serial Mode
In the serial programming mode, all master registers are
loaded with data, making it unnecessary to specify an output
address (A2:0). The input data format is D3-D0, starting with
OUT0 and ending with OUT7 for 32 total bits (i.e., first bit
shifted in is D3 for OUT0, and 32nd bit shifted in is D0 for
OUT7). Only codes 0000 through 1010 are valid serial mode
commands. Code 1010 disables an individual output, while
code 1001 enables it. After data is shifted into the 32-bit
Master Register, it transfers to the Slave Register on the
rising edge of the LATCH line (Edge mode), or when
LATCH = 0 (Level mode, see Figure 10).
Figure 6 shows a typical application of the HA457 for driving
75Ω loads. This application shows the HA457 digital-switch
control interface set up in the 7-bit parallel mode. The HA457
uses 7 data lines and 3 control lines (WR, CE and LATCH).
The input/output information is presented to the chip at A2:0
and D3:0 by a parallel printer port. The data is stored in the
master registers on the rising edge of WR. When the LATCH
line goes high, the switch configuration loads into the slave
registers, and all 8 outputs reconfigure at the same time.
Each 7-bit word updates only one output at a time. If several
outputs are to be updated, the data is individually loaded into
the master registers. Then, a single LATCH pulse can
reconfigure all channels simultaneously.
An IBM compatible PC loads the programming data into the
HA457 via its parallel port (LPT1) using a simple BASIC
program.
A2:0
Selects
Output
Being
Programmed
Address
Inputs are
Irrelevant for
These
Functions
TABLE 1. PARALLEL INTERFACE COMMANDS
D3:0
ACTION
0000 to 0111 Connect the input defined by D3:0 to the output selected by A2:0. Doesn’t enable a disabled output.
1000
Connect the output selected by A2:0 to GND. Doesn’t enable a disabled output.
1011
Asynchronously disable the single output selected by A2:0, and leave the Master Register unchanged.
1100
Asynchronously enable the single output selected by A2:0, and leave the Master Register unchanged.
1101
Asynchronously disable all outputs, and leave the Master Register unchanged.
1110
Asynchronously enable all outputs, and leave the Master Register unchanged.
1111
Send a Software pulse to the Slave Register to load it from the Master Register, iff, the LATCH input=1. If the
LATCH input=0, then this command is a NOP. The Master Register is unchanged by this command.
1001 or 1010 Do not use these codes in the parallel programming mode. These codes are for serial programming only.
D3:0
0000 to 0111
1000
1001
1010
1011 to 1111
TABLE 2. SERIAL INTERFACE COMMANDS
ACTION
Connect the output to the input channel defined by D3:0. Doesn’t enable a disabled output.
Connect the output to GND. Doesn’t enable a disabled output.
Enable the output and connect it to GND. The default power-up state is all outputs disabled, so use this code to enable
outputs after power is applied, but before programming the switch configuration.
Disable the output. The output is no longer associated with any input channel; the desired input must be redefined after
reenabling the output.
Do not use these codes in the serial programming mode.
SER/PAR
H
L
L
TABLE 3. DEFINITION OF DATA AND ADDRESS BIT FUNCTIONS
D3
D2
D1
D0
A2:0
COMMENT
X
X
Serial
Serial
X
32-Bit Serial Mode
Data
Data
Output
Input
H
Parallel Data Parallel Data Parallel Data Output Parallel Mode; D2:0 define the
Input
Input
Input
Address command to be executed.
L
Parallel Data Parallel Data Parallel Data Output Parallel Mode; D2:0 define the
Input
Input
Input
Address Input Channel
8