Joymega modification

Por jltursan

Prophet (2164)

imagem de jltursan

01-10-2012, 13:26

I've recently adapted some megadrive pads to MSX following the joymega specs and I must say that I'm great ly impressed. All buttons (A,B,C,X,Y,Z and Start) are scanned!. So far I've only find the following software patched to support the mod:

  • FireHawk-HDD
  • Vampire Killer
  • ASO
  • JoyMega and JoyTest tools

Just out of curiosity, is there any other known software already adapted or being developed?

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Por norakomi

Paladin (982)

imagem de norakomi

01-10-2012, 15:32

hi
fantastic work !!

i am working on a port of streetfighter 2 for the msx.
i have already 7 characters working, and i ordered 3 of those megadrive pads from korea.
i also read the specs about adapting the joypads, however, this is chinese to me, thus this information doesnt
really help me much Smile

i would love to get them to work ingame, i need at least 4 buttons to work, i use 2 buttons for punch
and 2 buttons for kick.

also how do you read the buttons using assembly-code ?

i suppose you did some soldering on the wiring, could you maybe explain how you did this ?

thanks for all the help

Por jltursan

Prophet (2164)

imagem de jltursan

01-10-2012, 17:30

Although easy, some minimal skills are needed to mod a pad, you'll need also a voltmeter and, obviously, a solder iron.
As there're a lot of different pad models, each one has it's own way to be modded. I'll try to explain a bit the mod from a generic point of view.

If you look carefully the colored picture at the above page you'll notice that in the upper side goes the MSX joystick connector and in the bottom the inner connections of the pad are represented. Basically you leave as they are pins from 1 to 6; you're only going to change pins 7-9 as follows:

Inside the pad:

1) Locate solder pads from pin 7 to 9 of pad connector (voltmeter required!) and desolder the wires. Of course, take note of each color and position (7-9) carefully.
2) Now take the old wire 7 and solder it in the old wire 9 place. You've tied Trigger 2.
3) Take the old wire 9 and solder it in the old wire 8 place. You've tied GND.
4) Now, the last desoldered wire (old 8) goes to pin 1 from IC 74LS04 (refer to picture). You can glue the IC somewhere inside the pad. Feel free to bend the IC legs as you need.

Now you need to solder some extra wires:

5) From pin 7 of 74LS04 to the same place where you soldered wire in step 3.
6) From pin 14 of 74LS04 to a source of +5V. You can locate for example, the solder pad of pin 5 of the pad connector.
7) From pin 2 of 74LS04 to old wire 7 place (last free one). Noy you've SELECT signal.

Double check all connections against pinouts!.

Now, setup a MSX-DOS disk with the JOYTEST tool (downloadable in the above page) and check the working of the modded pad :-)

Check also this spanish guide to get some ideas...

The assembly code is really easy. Look for the source code inside the Joymega package at the bottom of the author's page.

Por norakomi

Paladin (982)

imagem de norakomi

05-10-2012, 12:19

thanks ill give it a try