VK202-25 rev. 05
6
FF
0x0C
Clears the display and puts the cursor at the top left
BS
0x08
Moves the cursor one position to the left and clears that position.
Note: These command characters are not guaranteed to work on other Matrix Orbital display
modules. If you want your code to be portable, use the appropriate commands listed later in the
manual instead.
If you want to exercise some of the other features of the VK202-25 you'll need to write a program (in any
convenient language such as Basic or C) to issue the required command strings. Most terminal programs are
unable to issue the 0xFE character needed as a command prefix. You probably won't need to do this at the
initial testing stage.
If you've reached this point and operation is normal, you can be confident that your VK202-25 works
properly.
1.6 Trying out a Keypad
Since a number of different keypad types can be connected to the VK202-25, the results you get may be a
little unpredictable. At this point all we need to do is make sure that your keypad and interface work, and
possibly generate an ASCII map for your programming needs.
The keypad interface on the VK202-25 converts a row/column connection to an ASCII character. By
default, a keypress is transmitted as serial data immediately. Keypad buffering can be selected using the
appropriate commands.
1.6.1 Here's what to do:
1. Your PC should be running a terminal program, such as Hyperterm (as in the previous section).
2. With the VK202-25 connected to the PC, plug in your keypad. If your connector has fewer pins than
the one on the VK202-25, center it as well as possible.
Note 1:
The keypad connector must be wired with columns on one side and rows on the other side of
the center of the connector. If your keypad isn't wired this way you will need to make an adapter or
rewire the connector to meet this requirement.
Note 2:
The connector is reversible. Reversing the connector will not damage the keypad or the
VK202-25, but it will change the ASCII character map.
3. Press a key on the keypad. An upper case ASCII character (A-Y) should appear on the PC screen.
Different keys should generate different characters.
If you want to experiment, reverse the connector and see if it generates a more logical set of characters.
Ultimately, the program in your controller will have to "map" these characters to the ones marked on the
keypad, which will likely be different.
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