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

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