Interfacing a keyboard PS/2 with the Picaxe 21X-1 in 3 easy steps

By Boris
@ October 30, 2008

• CPU: Picaxe 28X-1
• Operating system: Windows XP Pro
• Power source: 5 VDC @ 02 Amps
• Programming language: Picaxe basic
• Sensors / input devices: PS/2 Keyboard

So one thing that I have been wanting to do is connect a keyboard (PS/2) to the Picaxe.

This is the first step to a whole slew of applications. Control Robots with a keyboard, make a computer, etc...

Just offering another source of info on how to do this.

It's pretty easy to do.

Before you get started here's a list of what I used.

Picaxe "Canuck" 28X-1 Kit --bought from HVW Tech Canada

Standard Breadboard

Breadboard Voltage Regulator -- converts 6~18 VDC to 5VDC @ 0.5Amps, bought from HVW Tech Canada

USB Download cable -- (using the serial one won't make a difference)

You NEED two 4.7k resistors on the CLK and DATA line -- I used 20 470ohm resistors soldered together :P

*to make it look cleaner, should only be temporary*

PS/2 Port -- I got mine from an old P2 motherboard

There are several ways to go about this step:

If you don't want to ruin a keyboard or want to use a temporary one (until you can acquire one you're willing to spare) then..

Either desolder a keyboard port from a motherboard or connect pins/clamps to the male end of the plug.

You could also cut the cable really short then solder pins onto the line and plug that directly into a breadboard.

Here is a picture of mine ( notice I used 10 * 470ohm resistors to get a 4.7k resistor )

The keyboard would not transmit data of any sort to the Pic unless I had these in.

The schematic from "Picaxe manual #2, Page 42"

From here if you're on the Picaxe 28X-1 then you have to use the command

"Kbin[timeout, address], variable"

The above command broken down;

Kbin = Keyboard input

Timeout = How long the Pic will wait until moving on to address

Address = Where to go when it timesout

Variable = Value

or

"Kbin variable"

Kbin = Keyboard input

Variable = Value

Here is my test code.

-------------------------------------

'Boris Jovic Keyboard Input Test

main:

kbin[1000,main],b1

debug b1

goto main

-------------------------------------

And that's it, the values that come back in Debug will most likely be wonky until you set each value into eeprom.

Thanks for reading! Good luck.