MC145192EVK Datasheet, PDF (6/48 Pages) Motorola, Inc – Evaluation Board Manual

Up to three EVK boards can operate independently from one printer port. All lines on the printer port are
connected to every EVK. Even with three boards operating, only three output lines (Clock, Data and
Load) from the printer card are used. If two boards are controlled together, data for the second board is
received from the Output A of the first. Output A is a configurable output on ’192/202 devices, which in
this case is used to shift data through chip 1 into chip 2. Output A and Data are connected using a printer
port input line. This was done to avoid connecting extra wires. Fortunately not all port input lines are
needed for computer input. Load and Clock are common to both boards.
A three–board cascade is handled similarly to a two–board cascade. Out A on the first board is fed to
Data on the second. Out A on the second connects to Data on the third. Instructing the program on the
quantity of boards connected together allows it to modify the number of bits sent.
All boards have a DIP switch S1 which gives each a unique address. The configuration menu is used to
tell the program what type of board is connected at a board address. Switch positions for all possible
addresses are given in Figure 2.
Single Board Operation
Closed
1 234 5678
Open
Two– or Three–Board Cascade
Board A
Closed
1 234 5678
Open
Board B
Closed
1 23 4 5 6 78
Open
Board C
Closed
1 23 4 5 6 78
Open
Figure 2. Switch Positions
MC145192EVK • MC145202EVK
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MOTOROLA