Atari 2600 Analog Paddles On The Jaguar

[Zerosquare]

See there for details.

What do you think ?

[Gorf]

See there for details.

What do you think ?

 

 

There have been small enough chips(those Anolog Devices 8 pin

dips) that one could have used...probably not as simple as those

chips you got there but it's about time someone did this.

 

Well done! Very neat too. Excellent Job!

[potatohead]

I think this is a great idea. Pack 'em in with a game, like what was done with Indy 500.

 

Tweak that for analog joysticks while the work is getting done. Those things are sweet, and the Jag has plenty of horsepower to really do great things with these kinds of controls.

[Fadest]

I think this is a great idea. Pack 'em in with a game, like what was done with Indy 500.

They will work with at least my warlords clone, but it will be released with the same license than my Yastuna games for Lynx (freeware, free to use on emulator, flash card-like devices, free to build your own physical support -CD or cartridge, and free to sell them), so no packaging (except if someone make a physical release of the game for sale and want to add adapter with them)....

 

But the main question is, when will the game be ready and released ?

[Pocket]

That is the BIG question

 

Congrats Zero !

Edited August 16, 2009 by Pocket

[BuddyBuddies]

Very cool buddy!

[Zerosquare]

Thanks everyone

 

Beware : upon checking, it seems that the 74HC4538 and 74HCT4538 ICs are not 100% compatible with the standard 4538. I think it could be fixed in software, but that would require an additional setting. In the meantime, I recommend against using them.

[Gorf]

Some inquiry:

 

On these Atari 2600 paddles adapters, how much coding is involved?

I've used the old Astrocade and A8 pot ports but those are handled

for you in the OS and you only need to read them.

 

I am assuming that with this you need to trigger the A2D to sample the input

for a few milli/micro seconds, and then read in some serially shifted bits from

a port which is the result of the conversion? ( i am assuming these steps based

on some old chips.)

 

I actually like the feel of using an encoder emulating a pot much better.

It's smoother, more accurate.

 

However, most folks can get their hands on a set of Atari 2600 paddles a lot

easier than, having to deal with encoder circuitry. This would be worth it to

a developer to support this that might be developing a game/app with a need

for such a device.

 

Again, nice work.

[Zerosquare]

The adapter works very much like the 2600 hardware, i.e. by measuring the time needed for a capacitor to charge, with the current being supplied through the potentiometer in the paddle. Basically, you send a pulse to "trigger" the IC, which then generates a pulse whose length is linearly proportional to the angle of the paddle. It's one of the easiest and cheapest way to do A/D conversion for potentiometers.

 

(Note that you can't wire a 2600 paddle directly to a "normal" ADC, since they are connected in rheostat mode, not voltage-divider mode. Adding a pull-down resistor to ground works, but the relationship between the readings and the angle is non-linear.)

 

On the 2600, measuring the pulse width is usually done by checking the state of the input for each (or every 2) scanline.

In my Jaguar code, I use one of Jerry's timers to trigger a DSP interrupt each 50 µs approximately. You can lower the CPU usage at the expense of precision by using a longer period. Another option would be to run the code during the I2S audio interrupt.

 

I will release the code soon.

[Gorf]

I figured it was somewhere along those lines. This could certainly come in handy if someone ever

gets one of those 2600 emu's to work on the Jag.