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Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 10:10 am
by TomD
Me again and another joystick question
This time around the question is 5V is actually needed for most joysticks (on pin 7 for Kempston/Atari)? I know the Megadrive pad needs it (on pin 5), but only if you want all the buttons to work as it works fine passively but only two fire buttons register (B & C)
I've got a pretty sizeable collection of joysticks from the 80s and I've not found one that needs 5V. MasterSystem 2 button doesn't, Amstrad GX4000 doesn't, Competition Pro nope, ZipStick nada... Autofire circuits also don't seem to need it with my ZipStick working fine. Note this is the separate 5V on pin 7, not the direction pins or fire buttons.
Sinclair didn't add it to their joystick interface but Kempston did and I'm just wondering why? Most joysticks just connect the direction/fire pins to ground to activate, meaning you only need to pull up the pins to get it to work.
TomD
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 10:18 am
by AndyC
Isn't it essentially anything with autofire? Or anything that used additional logic to multiplex buttons on a single wire (hence the MegaDrive pads needing it).
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 11:09 am
by TomD
AndyC wrote: ↑Tue Nov 14, 2023 10:18 am
Isn't it essentially anything with autofire? Or anything that used additional logic to multiplex buttons on a single wire (hence the MegaDrive pads needing it).
My Zipstick with autofire works fine without it. I took it apart and it seems the autofire circuit is just a simple transistor circuit powered form the fire pin, so as long as that has power it works fine. Let me try and find another one with autofire to check.
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 1:36 pm
by cj7hawk
Power is only used when the joystick has active circuitry, or is analog or is a mouse.
It is possible to build a Kempston interface that populates both the Joystick register and the Mouse register at the same time, so both items will work in it like an autodetect, though I'm not sure that all software would expect that, and the joystick and mouse data might conflict.
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 1:45 pm
by 1024MAK
There’s two types of auto-fire joysticks. Those that need a +5V supply on pin 7 and those that “steal” power from the fire button circuit (or indeed from any of the direction circuits).
I have some of each (although I can’t tell you off the top of my head which are which).
There’s also two types of auto-fire. Some joysticks even have a mode select switch. Either auto-fire when the trigger/button is pressed, or auto-fire in addition to the trigger/button (in other words, continuous auto-fire).
I’ve bought used/second hand/preloved joystick interfaces before where it’s been modified to provide a +5V supply to pin 7.
Mark
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 2:10 pm
by Joefish
And that's assuming the interface uses 0V as the common and +5V on the switch lines. Some are the other way round!
I know at least that dual-port DK'Tronics uses 0V as common on one side and +5V on the other. It's because one side is Sinclair / Keyboard, and the other side is Kempston, so the 'on' bits are inverted on one and not the other. I can't remember which way round it is though.
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 3:25 pm
by 1024MAK
Some of the early Kempston Electronics and copies/clones/compatibles used the +5V line for the common (pin 8). This makes no difference for a joystick that only uses mechanical switches/contacts.
These don’t work with any auto-fire joysticks or other devices that have active electronics.
Mark
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 4:09 pm
by Seven.FFF
cj7hawk wrote: ↑Tue Nov 14, 2023 1:36 pm
It is possible to build a Kempston interface that populates both the Joystick register and the Mouse register at the same time, so both items will work in it like an autodetect, though I'm not sure that all software would expect that, and the joystick and mouse data might conflict.
They can indeed conflict. In modern combo interfaces, where a fuller (not Fuller!) partial decoding is cheaper, it's usually usually done like this:
Code: Select all
+-+-++-------------------+---------+--------------------------------+
|R|W||5432 1098 7654 3210|Port(hex)|Description |
+-+-++-------------------+---------+--------------------------------+
|*| ||XXXX 1011 1101 1111| 0xfbdf |Kempston mouse x |
|*| ||XXXX 1111 1101 1111| 0xffdf |Kempston mouse y |
|*| ||XXXX 1010 1101 1111| 0xfadf |Kempston mouse wheel, buttons |
|*| ||XXXX XXXX 0001 1111| 0x1f |Kempston joy |
+-+-++-------------------+---------+--------------------------------+
However some games deliberately read Kempston joystick with IN 0xdf, and put random crap on the upper 8 address bits. This breaks the disambiguated decoding and causes conflicts again.
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 7:08 pm
by TomD
Thanks for all the replies. I did manage to find an autofire joystick that needed the 5V connection so answered my own question. It was a Quickshot II Turbo. Interestingly it works fine with a much lower voltage (3v3) so will assume its a similar transistor based circuit.
TomD
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 7:14 pm
by spider
Interesting to know as I'd always -assumed- the autofire function would require a 5v line.
For my own gaming preferences, typically I'd not need such a feature.
I can't recall exactly if the Megadrive pads fully functioned on both Sinclair and Kempston, likely I got annoyed and modified the pad so all three buttons worked as one "fire" , long ago so not sure.
Could be wrong but I am half sure -some- types of sticks likely not for our machines would accept a couple of AA batteries too, for functions.
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 7:21 pm
by Seven.FFF
I'm not sure, because I never had any interest in the C64/Amiga scene, but I think the wiring was for 3 button quadrature mice, and while the sticks always had the potential to coexist for the same wiring, nobody apart from much more recent hobbyists ever made any. So nobody made any games either. Similar lowest common denominator factors as 2 button on the Spectrum.
Best to stick to Sega 3 or 6 button protocol IMHO, as they actually do exist and people use them. There are plenty of sticks around for people that don't like gamepads.
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 8:01 pm
by 1024MAK
IIRC, the Quickjoy Jet Fighter Joystick SV-126 also needs a +5V supply on pin 7.
Mark
Re: Do any joysticks actually need 5V power?
Posted: Tue Nov 14, 2023 10:34 pm
by Seven.FFF
Seven.FFF wrote: ↑Tue Nov 14, 2023 7:21 pm
but I think the wiring was for 3 button quadrature mice
Darn it, this was meant to be a reply to
this thread.
Re: Do any joysticks actually need 5V power?
Posted: Wed Nov 15, 2023 1:32 pm
by TomD
Seven.FFF wrote: ↑Tue Nov 14, 2023 7:21 pm
I'm not sure, because I never had any interest in the C64/Amiga scene, but I think the wiring was for 3 button quadrature mice, and while the sticks always had the potential to coexist for the same wiring, nobody apart from much more recent hobbyists ever made any. So nobody made any games either. Similar lowest common denominator factors as 2 button on the Spectrum.
Best to stick to Sega 3 or 6 button protocol IMHO, as they actually do exist and people use them. There are plenty of sticks around for people that don't like gamepads.
That does make sense as the same port used for a mouse. You are probably right in getting it to work with the Sega pads makes the most sense.
TomD
Re: Do any joysticks actually need 5V power?
Posted: Wed Nov 15, 2023 4:43 pm
by Seven.FFF
TomD wrote: ↑Wed Nov 15, 2023 1:32 pm
You are probably right in getting it to work with the Sega pads makes the most sense.
I have schematics for 3- and 6- button Sega controllers, if you're interested in exploring that part too. Not for the host side, but I think you're going to do that part with a pico, and you have it well-covered.