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Extra joystick buttons for the minimig

The minimig is a great project designed by only one man: Dennis van Weeren. Today lot's of other people are making imporvements on the publicly released code of the minimig which is great because this means that new functionality is added and bugs (if there were any) will be fixed.

A nice example of the extra functionality of the minimig is extra joystick button(s) to improve usabillity. By adding an extra button to your joystick, you can controll your complete minimig with your joystick from your lazy chair. The joystick below has the left button connected to UP&DOWN, when pressed the minimigs OSD menu pops up (or close if allready open) and then you can easily and navigate through the menu using the normal joystick controls up/down/left/right. To select any option, press fire button. This joystick mod works from version FYQ100818 & PGL100818 and higher.

Because I always like symetrical design I added 2 buttons, one that combines UP & DOWN (pops up the OSD menu) and one the combines LEFT & RIGHT. The last one has no function yet but perhaps in the future this will be added, I do no know. I think the extra buttons look cool. The UP & DOWN button works like a charm and now I never need to walk toward the minimig from my lazy chair to enter the OSD menu to swap/select a disk.

But how do these extra buttons work and how does this look like. Below some photos of my modded joystick.




How does it work:

Well actually it is quite simple, it is impossible for the user to move up and down at the same time. It is also impossbible to move left and right at the same time. So these combinations are unused by every joystick ever used on the Amiga. This is great because this means that we can use these digital combinations of signals to indicate the state of another button. The only thing we require is 2 buttons and 4 shottky diodes (I used the BAT54C, that is a 3 pin device that holds 2 shottky diodes with their Cathodes connected). The diodes are required so that a simple single throw button can be used. But if you have a double trow button lying around then you do not need the diodes. The diodes simply prevent that up and down (or left and right) are shorted during the time that the button isn't pressed. One more thing about the diodes, they have to be shottky. Shottky diodes have a very low voltage drop of approx 0.2V if you use standard diodes the voltage drop across the diode would be too high and the mod simply won't work.