NB : Pour Amiga il faut inverser XB et YB (pin 1 et 4 du DB9)
A new atari mouse (from a serial mouse) (top)
What do I need to buy?
- a 3 button serial mouse. I used a Trust-mouse, but the description can easily be adapted for other mouse types.
- a piece of 9-wire cable. This must be as flexible as possible!
- a 9 pin subD connector
- 4 47k resistors 1/8 watt
- an 74HC14 (hex schmitt-trigger)
- maybe an extra resistor (read on...)
What equipment do I need?
- a soldering iron (max. 35Watt, thin point)
- a solder sucker
- some small gauge wire
- a piece of shrink sleeve
- a hobby knife (to cut unwanted PCB tracks)
- some experience in soldering is mandatory
Before making the mouse unusable as a serial mouse, see if you can identify the following items:
- the IR-LEDs
- the photo transistors (there might be 4 of them when they are not integrated as indicated by the dotted box in the schematic).
Also, follow the trace connecting the IR-LEDs. There should be a resistor in this path. The extra resistor you need should have approximately the same value as the resistor you find here.
- start removing the components you don't need (IC, crystal). Keep the traces and holes intact and remove solder from the holes. You might want to re-use the holes.
- find some suitable spots for the power-supply (+5v + GND). These usually have the most wires connected too...
build the circuit for the IR-LEDs, buttons and connect the elco (watch the polarity!). Cut traces if you have to...
- Identify the traces from the photo-transistors that you need to connect to. When you have, put the 74HC14 on its back on the pcb and figure out how you can connect the resistors to the traces and the 74HC14. Put the resistors in place (adding shrink sleeves when you feel it's necessary). When that's done, put a piece of double-sided sticky tape on the back of the 74HC14 and stick it onto the pcb.
- connect the resistors (as shown in the schematic) and the power supply to the 74HC14 (+5 = 14, gnd = 7).
- make a visual inspection of your work. It's much easier to correct things without a few meters of cable attached.
- Connect the 9 pin subD connector to one end of the cable. Write down the colour/pin relations.
- connect the other end of the cable to the various points in the modified mouse.
- attach the mouse to your atari and power on the atari. If the power led on the atari doesn't light-up within a second, turn off your atari immediately and start looking for shorts or other problems.
- start GEM or X to see if your mouse works. There are a few major problem areas:
- none of the buttons work - very unlikely unless you made a cabling error.
- the middle button does not work - the connection between mouse connector pin 5 and joystick pin 1(??) is missing. You will have to make that yourself.
- the mouse movement is flaky - add the extra resistor by soldering it parallel to the existing resistor in the IR-LED circuit. Since the power supply has dropped (from approx. 15V to 5V), the IR-LEDs may not provide enough illumination on the photo transistors.
- one or all of the movements are reversed - exchange XA with XB or YA with YB (dependent on the reversed direction
- frob a bit with the cable throughput. Since the new cable is thicker than the original, check the functioning of the middle button with the cable below it.