Introduction

This is a simple project to connect a PS/2 mouse to an Apple ADB system. Right now it is only developed and tested on an Apple IIgs but it might work with ADB Macs as well.

Warning

This code is pre-alpha quality. I threw it together in a couple days and it completely neglects certain aspects of the ADB bus such as collision detection. Lots of debugging bits, used and unused, remain in the code. USE THIS CODE AT YOUR OWN RISK! ASSUME IT WILL CATCH YOUR COMPUTER ON FIRE!

Details

Hardware Configuration

This project should work on any Arduino with an ATMega8 series chip (ATMega8/ATMega168/ATMega328).

First, hook up the ADB and PS/2 ports to the Arduino as follows:

PS/2

|Name |PS/2 pin|Arduino pin|AtMEGA pin| 
|:----|:-------|:----------|:---------| 
|DATA |1       |4          |6 (PD4)   | 
|GND  |3       |GND        |8+22      | 
|VCC  |4       |+5V        |7+21      | 
|CLOCK|5       |3          |5 (PD3)   |

ADB

|Name|ADB pin|Arduino pin|AtMEGA pin| 
|:---|:------|:----------|:---------| 
|ADB |1      |8          |14 (PB0)  | 
|VCC |3      |+5V        |7+21      | 
|GND |4      |GND        |8+22      |

The system will draw power from the ADB bus and supply it to the Arduino and the PS/2 mouse.

Note that you can substitute other pins for PS/2 clock and data if you like, just change the #define PS2CLOCK 3 and #define PS2DATA 4 lines in the code. However, you MUST NOT change the ADB pin. It MUST be connected to Arduino pin 8. This is because the timer interrupt used only works on pin 8.

If you find that your mouse isn't working, particularly if it is a USB mouse with a PS/2 to USB adapter, add 10k pullup resistors to the clock and data lines.

Software configuration

You will need to download the PS/2 mouse library from PS2-Mouse-Arduino and place it in your Arduino/libraries folder. Rename it to something without dashes (like "PS2") or Arduino will complain.

If you are using Arduino 1.0 or above, edit the file PS2Mouse.cpp and change the line #include "WConstants.h" to #include "Arduino.h" .

After that you should be good to go. Upload the code to your Arduino, plug in the PS/2 mouse and the ADB bus, and enjoy!

Bugs

If the PS/2 mouse is not plugged in when the Arduino starts up, the code will hang. Reset your Arduino or power cycle your computer after plugging the PS/2 mouse and it should start working.

This code assumes your Arduino is running at 16MHz. It will not work at other speeds.

Mirror Info

Mirrored from the now-defunct Google Code by [Scott Alfter](mailto:scott at alfter dot us) on 29 November 2018.