6 trying out a keypad – Matrix Orbital PK202-25 User Manual
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4. Connect the power connector, making sure that the +5V goes to V+. Turn on the power: the display
should come on.
1.5 Trying Out the PK202-25
The unit should be connected to power. The PC and display should be on. To experiment with typing
text, run a PC terminal program, such as Hyperterm. Make sure it’s configured to use the correct port. Set
the baud rate to 19,200. If characters are typed on the keyboard, they should now appear on the display
screen. Text will wrap around to the next line when the end of a line has been reached.
A few common ASCII control characters work as follows:
Table 1: ASCII Control Characters
Character Hex value Function
CR
0x0D
Moves cursor to beginning of the
current line.
LF
0x0A
Moves cursor to beginning of the
next ( or previous ) line.
FF
0x0C
Clears the display and puts the cur-
sor 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.
To exercise some of the other features of the display, a program (in any convenient language such as Basic
or C) will need to be written in order to issue the required command strings. Most terminal programs are
unable to issue the 0xFE character needed as a command prefix.
1.6 Trying Out a Keypad
Since a number of different keypad types can be connected to the display, the results may be a little
unpredictable. At this point all we need to do is make sure that the keypad and interface work, and possibly
generate an ASCII map for any programming requirements. The keypad interface on the display converts a
row / column connection to an ASCII character. By default, a keypress is transmitted as serial data immedi-
ately. Keypad buffering can be selected using the appropriate commands.
1.6.1 Here’s what to Do
1. The PC should be running a terminal program, such as Hyperterm.
Matrix Orbital
PK202-25
3