Sega MD Controllers do/don't damage Amigas? - Page 2

happymondays · 28 October 2014, 03:00

Using Megadrive controllers for some time (years) now on A500 and A1200, I have never experienced anything bad, except for the lack of an actual joystick.

Daedalus · 02 December 2014, 11:08

Just wanted to add a little schematic I came up with for a "dumb" adaptor for 3-button Sega Megadrive / Genesis controllers. It was part of a discussion on Jens' new products thread and I don't want to pollute that thread any more with off-topic stuff like this. Basically, pin 5 on the Amiga *is* used as an output for CD32 controllers, and I suspect this is where you're most likely to run into trouble / cause damage. I have a more technical explanation in that thread (Clicky!) but probably best to reply here instead. The C64 is more at risk than the Amiga due to how it re-uses the CIA pins for different things. Anyway, this adaptor should protect both Amiga and C64 from any potentially harmful effects:

Click here!

Edit: I'd add here as well that pin 5 is not set to output for reading the middle mouse button - it's set to input just like the left and right button.

robinsonb5 · 02 December 2014, 13:26

Quote:

Originally Posted by Daedalus

Anyway, this adaptor should protect both Amiga and C64 from any potentially harmful effects:

Looks good - just make sure you don't plug a 3-button mouse into that and press the middle button! For the Amiga it's better to just swap pins 5 and 7 in the adapter because then certain software can actually read the extra buttons.

Quote:

Edit: I'd add here as well that pin 5 is not set to output for reading the middle mouse button - it's set to input just like the left and right button.

<nitpick>
"These lines can also be used for button inputs. A button is a normally open switch that shorts to ground. The Amiga must provide a pull-up resistance on the sense pin. To do this, set the proper pin to output, and drive the line high (set both OUT... and DAT... to 1)."
-- Hardware Reference Manual
</nitpick>

Daedalus · 02 December 2014, 13:46

Yeah, very good point about the 3-button mouse! A 1k resistor inline with that should protect from any problems that might cause and still allow it to be used. Is there any software that will actually read a MD pad with the pins swapped? I was thinking it would be best to not involve pin 5 at all and lock the MD pad to basic mode in case some software tries to read a CD32 controller and messes up your buttons and left/right control, but I guess the chances of that are pretty slim.

Hmmm... Interesting from the hardware reference manual, it's no different from the left or right buttons, they all need to be driven high to detect button presses, and given that pin 5 defaults to high I thought it defaulted to that setup like pins 6 and 9 do. They're all still read as inputs with no output normally required from the software side... I wonder if that's just in case something else was previously using that line and left it in a low state?

robinsonb5 · 02 December 2014, 18:20

Quote:

Originally Posted by Daedalus

Yeah, very good point about the 3-button mouse! A 1k resistor inline with that should protect from any problems that might cause and still allow it to be used. Is there any software that will actually read a MD pad with the pins swapped?

If memory serves, Flashback supports it - and I'm pretty sure there's a DOOM port which does, too.

Quote:

They're all still read as inputs with no output normally required from the software side...

Yes, the "input" mode vs. "output mode" is a bit of a red herring - the distinction is actually "analogue input" vs "digital I/O". And if all you want to do is read the buttons you'd probably not bother writing to POTGO at all, and leave it in the state to which Kickstart initialised it - i.e. digital IO, logic high (pullup enabled).

Toni Wilen · 02 December 2014, 19:00

Quote:

Originally Posted by robinsonb5

And if all you want to do is read the buttons you'd probably not bother writing to POTGO at all, and leave it in the state to which Kickstart initialised it - i.e. digital IO, logic high (pullup enabled).

Only works if reading mouse. Kickstart 1.x sets all pins to output mode. 2.0+ only sets mouse port to output mode by default.

RiP · 09 July 2018, 22:17

Quote:

Originally Posted by vext01

In conclusion, disconnect pin 5 of the MD controller

Is it safe to disconnect pin5 or should I swap 5<=>7 ?

Daedalus · 09 July 2018, 23:28

Swap pins 5 and 7, or for improved compatibility, connect pin 5 of the pad to pin 7 of the Amiga, and connect pin 7 of the pad to pin 7 of the Amiga through a 1K resistor.

th4t1guy · 10 July 2018, 16:02

One of the book that came with Hired Guns contained instructions on how to modify a MD controller to use multiple buttons for the game on the Amiga. Doesn't look like its in HOL though.

lilalurl · 10 July 2018, 18:04

Quote:

Originally Posted by th4t1guy

One of the book that came with Hired Guns contained instructions on how to modify a MD controller to use multiple buttons for the game on the Amiga. Doesn't look like its in HOL though.

Swap lines 5 and 7.

Lemaru · 10 July 2018, 23:38

If you swap pins 5&7 and then bridge them with a 470ohm resistor then you can get 6 button Sega pads working in ADoom. (Explains it in the ADoom guide)

I can't get this to work on a ln A600 though. Vaguely remember seeing it works on other machines fine but for some reason it doesn't work on the A600.

RiP · 11 July 2018, 21:09

Some sega gamepads have IC and some not, does it matter?

Daedalus · 12 July 2018, 01:13

All Megadrive gamepads must have an IC. If it doesn't, it will have a large number of transistors and diodes, and that wouldn't be very cost effective. If you mean Mastersystem pads, they're different. They don't have an IC, and they are 100% compatible with the Atari/Amiga pinout for 2-button controllers.

Hewitson · 12 July 2018, 11:06

Quote:

Originally Posted by Daedalus

All Megadrive gamepads must have an IC. If it doesn't, it will have a large number of transistors and diodes, and that wouldn't be very cost effective. If you mean Mastersystem pads, they're different. They don't have an IC, and they are 100% compatible with the Atari/Amiga pinout for 2-button controllers.

I wouldn't say 100% compatible. I'm sure I've heard stories of MS pads damaging C64's.

Daedalus · 12 July 2018, 15:19

Quote:

Originally Posted by Hewitson

I wouldn't say 100% compatible. I'm sure I've heard stories of MS pads damaging C64's.

I'd be interested to see some evidence of that, because any Mastersystem controller I've examined has been 100% compatible. It's more likely that whoever said this instead was confused between Mastersystem and Megadrive.

26 August 2018, 00:06

Just my personal anecdote but a couple of years ago I fried one of my A1200 mouse ports by plugging in a 3rd party mega drive controller. Obviously it was for player 2. But ever since, the mouse pointer will just wiggle one pixel left or right and not move otherwise. Had to do a software hack in my startup sequence to swap the ports and make it useable again. Not sure what’s blown. Could be CIA chip maybe??? So, use MD pads with great caution.

Daedalus · 28 August 2018, 11:18

It won't be a CIA that's damaged, more likely the small 74'166 chip that's used to multiplex the directional inputs on the ports, one of the related pull-up or suppression parts, or a physical issue like a damaged connection on the port. If it's something like that, it should be an easy fix, there are plenty of people in the UK who could fix it for you. This will be the case if a standard joystick on that port also has trouble working.

If a standard joystick in the mouse port works fine but the mouse doesn't, chances are that the 5V supply has been damaged to the port - either the current limiting 4.7 ohm resistor is burned out, or a trace is damaged. This type of fault could be caused by the controller shorting the 5V supply to ground.

If the other port is working fine then there is no custom chip damage, which is the more expensive / trickier repair, so that's good news at least.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Sega controllers on A1200 ?	asm1	support.Hardware	26	05 January 2023 07:40
Don Don Land by Sunteam	s2325	request.Old Rare Games	4	21 May 2022 20:32
Wireless Controllers	Washac	support.OtherUAE	3	01 March 2012 22:21
FS: Sega Megadrive II with all leads/controllers + games	Smiley	MarketPlace	3	05 July 2011 00:54
Sega controllers?	one1	support.Hardware	33	24 August 2007 15:43

28 October 2014, 03:00	#21
happymondays Registered User Join Date: Aug 2014 Location: Szeged Posts: 219	Using Megadrive controllers for some time (years) now on A500 and A1200, I have never experienced anything bad, except for the lack of an actual joystick.

02 December 2014, 11:08	#22
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Just wanted to add a little schematic I came up with for a "dumb" adaptor for 3-button Sega Megadrive / Genesis controllers. It was part of a discussion on Jens' new products thread and I don't want to pollute that thread any more with off-topic stuff like this. Basically, pin 5 on the Amiga is used as an output for CD32 controllers, and I suspect this is where you're most likely to run into trouble / cause damage. I have a more technical explanation in that thread (Clicky!) but probably best to reply here instead. The C64 is more at risk than the Amiga due to how it re-uses the CIA pins for different things. Anyway, this adaptor should protect both Amiga and C64 from any potentially harmful effects: Click here! Edit: I'd add here as well that pin 5 is not set to output for reading the middle mouse button - it's set to input just like the left and right button.

02 December 2014, 13:46	#24
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Yeah, very good point about the 3-button mouse! A 1k resistor inline with that should protect from any problems that might cause and still allow it to be used. Is there any software that will actually read a MD pad with the pins swapped? I was thinking it would be best to not involve pin 5 at all and lock the MD pad to basic mode in case some software tries to read a CD32 controller and messes up your buttons and left/right control, but I guess the chances of that are pretty slim. Hmmm... Interesting from the hardware reference manual, it's no different from the left or right buttons, they all need to be driven high to detect button presses, and given that pin 5 defaults to high I thought it defaulted to that setup like pins 6 and 9 do. They're all still read as inputs with no output normally required from the software side... I wonder if that's just in case something else was previously using that line and left it in a low state?

09 July 2018, 23:28	#28
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	Swap pins 5 and 7, or for improved compatibility, connect pin 5 of the pad to pin 7 of the Amiga, and connect pin 7 of the pad to pin 7 of the Amiga through a 1K resistor.

10 July 2018, 16:02	#29
th4t1guy Registered User Join Date: Mar 2002 Location: Kansas City, MO, USA Posts: 683	One of the book that came with Hired Guns contained instructions on how to modify a MD controller to use multiple buttons for the game on the Amiga. Doesn't look like its in HOL though.

10 July 2018, 23:38	#31
Lemaru Registered User Join Date: Oct 2016 Location: Berks, UK Posts: 269	If you swap pins 5&7 and then bridge them with a 470ohm resistor then you can get 6 button Sega pads working in ADoom. (Explains it in the ADoom guide) I can't get this to work on a ln A600 though. Vaguely remember seeing it works on other machines fine but for some reason it doesn't work on the A600.

11 July 2018, 21:09	#32
RiP Q Join Date: Feb 2017 Location: CD0: Posts: 139	Some sega gamepads have IC and some not, does it matter?

12 July 2018, 01:13	#33
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	All Megadrive gamepads must have an IC. If it doesn't, it will have a large number of transistors and diodes, and that wouldn't be very cost effective. If you mean Mastersystem pads, they're different. They don't have an IC, and they are 100% compatible with the Atari/Amiga pinout for 2-button controllers.

26 August 2018, 00:06	#36
Neakmenter Posts: n/a	Just my personal anecdote but a couple of years ago I fried one of my A1200 mouse ports by plugging in a 3rd party mega drive controller. Obviously it was for player 2. But ever since, the mouse pointer will just wiggle one pixel left or right and not move otherwise. Had to do a software hack in my startup sequence to swap the ports and make it useable again. Not sure what’s blown. Could be CIA chip maybe??? So, use MD pads with great caution.

28 August 2018, 11:18	#37
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,334	It won't be a CIA that's damaged, more likely the small 74'166 chip that's used to multiplex the directional inputs on the ports, one of the related pull-up or suppression parts, or a physical issue like a damaged connection on the port. If it's something like that, it should be an easy fix, there are plenty of people in the UK who could fix it for you. This will be the case if a standard joystick on that port also has trouble working. If a standard joystick in the mouse port works fine but the mouse doesn't, chances are that the 5V supply has been damaged to the port - either the current limiting 4.7 ohm resistor is burned out, or a trace is damaged. This type of fault could be caused by the controller shorting the 5V supply to ground. If the other port is working fine then there is no custom chip damage, which is the more expensive / trickier repair, so that's good news at least.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)