Sega Master System controllers on an Amiga?

[mrknight]

Master System and Mega Drive controllers are compatible in Amiga, but at the same time they are not. Let me explain...

Amiga power the joysticks with pin 7 and Sega power on pin 5. So why does the Sega pads work on Amiga? The answer is that Amiga also have a +5 voltage on pin 5. This pin is used for steering wheels and such. It's essentially reading an analogue signal like the PC gameport (do you remember those?). You can not draw as much current from pin 5 as you can from pin 7. Maybe this is the reason why some people have blown the CIA?

What happens when a Mega Drive drive controller is connected to an Amiga is that the Amiga power pin 7 is acting as the Select signal for Mega Drive and will output button B and C as Amiga button 1 and 2.

What you should do to do things right is to open the Sega controller and swap the wires so the controller is powered from pin 7 instead.

Please see these pinouts for reference:

Amiga:
http://www.allpinouts.org/index.php/Mouse/Joystick_Amiga_9_pin

Master System:
http://www.allpinouts.org/index.php/SegaMaster_System_%28SMS%29_and_MegaDrive_joystick

Mega Drive:
http://pinouts.ru/Game/genesiscontroller_pinout.shtml

[mrknight]

I hereby award you:
Best Message of the Year Award!

Thank you for that! I did some rewiring last months so it's still fresh in my head. The six button Mega Drive controllers are a bit more complicated since they seem to use the timing of the Select signal to read the X, Y and Z buttons. I can't find the link to that article right now...

Or get two 9 pin connectors, one male and one female and wire them up 1:1 apart from pin 5 & 7 which you swap.

I got a DB9 gender change shell for the very same reason. I did my rewiring on some cheap Mega Drive look alike pads that I got 2 of for ~$6 from eBay. Didn't want to rewire my real controllers. I will make a converter for those.

In fact, I bought an AVR programmer and some AVRs not long ago. With this I should be able to read all the buttons from a 6 button Mega Drive controller. And if I add some switches on the converter I can remap buttons and such. I think this project is more realistic than the 2MB chip RAM mod I asked about in another thread.

[mrknight]

The ADoom.readme from ADoom on Aminet directs to swap lines 5 and 7 and put a 470 ohm resistor between them (pins 5 and 7) for both 3 and 6 button Genesis controllers. The ADoom source should have Joe Fenton's code to read a 6 (or 3) button Genesis controller then. I believe the 3 button support is the same as described in the Hired Guns manual as well. It would be nice if we all used the same standards and were compatible .

Interesting. Sounds like it is used as a pull up resistor. I just had a quick look at the schematics for A500 R6A. Pin 1 to 4 (Up, DOWN, LEFT, RIGHT) are controlled by Denise. Pin 6 (FIRE1) is controlled by CIA. Pin 5 and 9 (POTX and POTY) are controlled by Paula. These two pins, as well as pin 6 (FIRE) are bi-directional. I guess ADoom uses pin 5 as a Sega Select and with this manage to read all buttons.

Here is the link to the specs. for 6 button Mega Drive controller I couldn't locate yesterday:
http://www.cs.cmu.edu/~chuck/infopg/segasix.txt