Atari joystick interface for BBC Micro?

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carlsson
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Atari joystick interface for BBC Micro?

Post by carlsson » Wed Feb 07, 2018 2:52 pm

What is the state of affairs when it comes to obtaining an interface to connect 1-2 digital Atari style joysticks to the analog port on the Beeb?

When I looked into this several years ago, there were close to no ready-made or even DIY solutions, and every eBay auction for an old Protek or other interface went way above what I was willing to pay.

I have been in contact with a manufacturer who could produce DIY soldering kits at around £10 + shipping. However I need to certify if there is any demand for a such product at that price, or if the market has been saturated during my absense. I'm not trying to step on somebody else's toes if there are one or more readily available solutions.

crj
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Re: Atari joystick interface for BBC Micro?

Post by crj » Wed Feb 07, 2018 3:43 pm

The interface would be a PCB, eight resistors, two 9-pin D types and a 15-way, yes?

My hunch is that there wouldn't be much interest in the kit of parts, unless it was the only option on offer. Some people would be more interested in a finished product. The people who are prepared to do the soldering would also either have the components lying around or could source them trivially, so would likely prefer to buy just the PCB.

JonC
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Re: Atari joystick interface for BBC Micro?

Post by JonC » Wed Feb 07, 2018 4:32 pm

Not sure if Bryce is still selling these;
http://www.stardot.org.uk/forums/viewto ... =8&t=10187
Jon
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1024MAK
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Re: Atari joystick interface for BBC Micro?

Post by 1024MAK » Wed Feb 07, 2018 6:02 pm

JonC wrote:Not sure if Bryce is still selling these;
http://www.stardot.org.uk/forums/viewto ... =8&t=10187
The earlier thread about that is here :wink:

Some links posted by me last year are here.

There are details of at least two DIY versions somewhere on here, or linked from the forum.

Mark

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tricky
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Re: Atari joystick interface for BBC Micro?

Post by tricky » Wed Feb 07, 2018 8:36 pm

There is a short discussion in my thread about interfacing Sega Mega Drive controllers, where someone has a fairly simple design for the Dragon32 that would translate quite easily to the beeb.
I have knocked up a designs in KiCad for Atari and Sega and have been dithering about ordering some PCBs.

I'm not planning on selling them, but will probably have a few spare. The BOM comes to about £2 if built on veroboard, but takes a few hours to build, so I would expect a parts one would be more attractive, soldering aside.

It is a bit more than eight resistors, which does work if you mod the joystick, but not as an adapter.

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1024MAK
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Re: Atari joystick interface for BBC Micro?

Post by 1024MAK » Thu Feb 08, 2018 1:03 am

Yes, some transistors are needed if an Atari 9 pin to BBC adapter is being built.

Mark

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Re: Atari joystick interface for BBC Micro?

Post by crj » Thu Feb 08, 2018 1:34 am

Hmm.

I instantly jumpted to the perhaps-naive conclusion that all you needed for each channel was:
  • Resistor from VREF to the input
  • Equal resistor from GND to the input
  • One Atari joystick direction switch shorts VREF directly to the input
  • The opposite Atari joystick direction switch shorts GND directly to the input
What am I missing which means that's not sufficient?

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1024MAK
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Re: Atari joystick interface for BBC Micro?

Post by 1024MAK » Thu Feb 08, 2018 3:15 am

The common connection in an Atari (compatible) Joystick is common to all the directional outputs (up, down, left, right) plus the fire button. That is, just to be clear, all the switch contacts use a single common connection.

If the Joystick is left in the "home" or "neutral" position, all contact switches are open circuit.

While the analogue joystick interface on the Beeb, in the "home"/"neutral"/"central" position has both it's two pots (potentiometers) also in the centre positions, each then produces half the reference voltage to each analogue input.
Move the Joystick in one direction and the pot rotates, the analogue voltage thens either goes to close to the reference voltage, or if moved the other way, it goes close to 0V.

Move the Atari Joystick in one direction and one contact makes, move it in the opposite direction and the other opposite direction contact makes.

If you open the Joystick and it has individual switch contacts (not all do), you could rewire it. Then all you need are some resistors.

Mark

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Re: Atari joystick interface for BBC Micro?

Post by 1024MAK » Thu Feb 08, 2018 3:26 am

Here is another thread on the subject Atari joystick on the BBC. This includes an article that has diagrams and text explaining the theory.

Mark

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Re: Atari joystick interface for BBC Micro?

Post by crj » Thu Feb 08, 2018 3:35 am

1024MAK wrote:The common connection in an Atari (compatible) Joystick is common to all the directional outputs (up, down, left, right) plus the fire button.
Oh, yeah, duh. That was even more obvious than I was expecting. /-8

carlsson
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Re: Atari joystick interface for BBC Micro?

Post by carlsson » Thu Feb 08, 2018 9:24 am

Thanks. Given that DIY:ers seem to prefer to do it entirely from scratch and there might be someone still selling assembled units on demand, I'll have to think this over if the kit solution is a waste of time and money. :?

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Elminster
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Re: Atari joystick interface for BBC Micro?

Post by Elminster » Thu May 03, 2018 4:48 pm

i rememebr using a website in Russian to build mine. Not found it yet.

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Elminster
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Re: Atari joystick interface for BBC Micro?

Post by Elminster » Thu May 03, 2018 7:53 pm

Found it after recovering all my bookmarks from backup. I followed this one ages ago and seemed to work fine.

http://zxjim.blogspot.co.uk/2012/05/aco ... apter.html

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1024MAK
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Re: Atari joystick interface for BBC Micro?

Post by 1024MAK » Thu May 03, 2018 10:13 pm

There is a newer thread here.

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Bryce
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Re: Atari joystick interface for BBC Micro?

Post by Bryce » Fri May 04, 2018 7:05 am

I still have a few of these: http://www.stardot.org.uk/forums/viewto ... =8&t=10187 left over if anyone is interested.

Bryce.

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marcusjambler
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Re: Atari joystick interface for BBC Micro?

Post by marcusjambler » Fri May 04, 2018 7:25 am

I'm interested in one please.
PM sent

Marcus

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Re: Atari joystick interface for BBC Micro?

Post by dhoggan » Wed Jul 11, 2018 7:31 am

Hi,

I guess this is one more for Bryce, but are any of these still available? I would send a PM, but not allowed to do so at the moment.

Thanks,

Dave
BBC Model B Issue 7 with MMC Card implant, Microvitec Cub 653.

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Elminster
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Re: Atari joystick interface for BBC Micro?

Post by Elminster » Wed Jul 11, 2018 8:30 am

While you wait for PM ability, Bryce is also over on Amibay if you have an account there instead.

http://www.amibay.com/showthread.php?76 ... ers/page11
Last edited by Elminster on Wed Jul 11, 2018 8:30 am, edited 1 time in total.

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Re: Atari joystick interface for BBC Micro?

Post by dhoggan » Wed Jul 11, 2018 11:36 am

Hi Elminster,

Thanks - I hadn't an account but have just set one up - probably worth it as I'm just beginning in the whole 8-bit scene. Well, beginning again I guess that should be!

I suspect that I probably won't be able to send a PM there either, but at least I can add a reply to the post you linked to.

Thanks,

Dave
Last edited by dhoggan on Wed Jul 11, 2018 11:52 am, edited 2 times in total.
BBC Model B Issue 7 with MMC Card implant, Microvitec Cub 653.

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Re: Atari joystick interface for BBC Micro?

Post by dhoggan » Wed Jul 11, 2018 10:15 pm

Just an update that thanks to the advice and help here, I have an adapter being shipped to me in the very near future. So thanks Elminster and also thanks to Tricky who sent a PM - I'm not allowed to reply to them yet!

Thanks,

Dave
BBC Model B Issue 7 with MMC Card implant, Microvitec Cub 653.


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kppot
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Re: Atari joystick interface for BBC Micro?

Post by kppot » Tue Jul 31, 2018 2:27 pm

Hey guys
Could please somebody help me with ordering the very same adapter from that Amibay person?
Problem is that Amibay totally bans me or does not let me create a new account. The adapter I need is here
http://www.amibay.com/showthread.php?76 ... k-Adapters
I can pay with Paypal or whatever means required

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danielj
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Re: Atari joystick interface for BBC Micro?

Post by danielj » Tue Jul 31, 2018 2:54 pm

Bryce is a user on here, I'll give him a nudge.

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kppot
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Re: Atari joystick interface for BBC Micro?

Post by kppot » Wed Aug 01, 2018 3:01 am

Cheers! I couldn't find him via Search, my bad :|

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Elminster
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Re: Atari joystick interface for BBC Micro?

Post by Elminster » Wed Aug 01, 2018 6:49 am

kppot wrote:
Wed Aug 01, 2018 3:01 am
Cheers! I couldn't find him via Search, my bad :|
He posted 9 posts further up this thread :)

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