Star Wars Yoke Centering (Perfect, but it is not!)

Altan

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I just spent an hour or so in the "pot test menu" getting my Star Wars yoke to center nicely inside the small box.

It's done! Yeah!

Now that I've got the hang of it, it's pretty easy.

But...

When the play the darn game, the crosshairs are NOT centered! It's about 1/3 from the left and 1/4 from the bottom.

Then I go back into the "pot test menu" and it's perfectly centered.

What am I missing? :(

... Altan

Note: if I move the controller all the way to the left and then all the way to the right, the crosshairs ARE centered. But I didn't expect to need to do this every time I power on the game
 
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You're not missing anything; you have to move the yoke around in a few circles to center it each time the game is powered on.
 
The manual says it is auto centering and to move from corner to corner diagonally a couple times to calibrate it.
 
Thanks guys.

I expected that doing the calibration in the diags would mean the cross hair would be "spot on" even before doing the so called auto calibration. Looks like that isn't the case.

I'm interested in whether other SWs owners out there, with their machine's pots/gears adjusted to within the small square, have the same cross hair starting point I'm seeing.

... Altan
 
I used to have a problem but it was because the controller itself wouldn't spring back to center. Replaced all the springs and gears with a Ram Controls rebuild kit and it is fine now although to make it perfect the pots should have been replaced.
 
My yoke controller springs back perfectly. I can move it away, release it, and it goes right back to neutral.

Below is a picture of the test diags when it springs back to neutral.

DSC_1287.jpg


And below is a picture of the cross hair when the game is initially powered on (with the yoke controller in exactly the same position as when the above picture was taken)

DSC_1288.jpg


Oh well. It's probably just the way it is. A bit surprising, however.

One more thing... regarding the EEPROM thought... the game seems to hold settings correctly so I think the EEPROM is good.

... Altan
 
That's totally normal, and mine does the exact same thing... like said earlier, just move the yoke to all extremes and it'll calibrate itself. I'm sure it wasn't a big deal in the arcades that the first person to play the game after power on was a little off until they travelled the full throw of the yoke.

DogP
 
@vicjw66: That can't be because the test screen is perfectly alligned in Altan's picture.

Actually, the calibration continues throughout the game. Whenever I am in the scene where you "dive into" the Deathstar, I hit all four corners quickly so it re calibrates. Not sure if it works right then but I do think it does.


I've actually never looked closely between the difference before I start a game....
 
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@vicjw66: That can't be because the test screen is perfectly alligned in Altan's picture.

Actually, the calibration continues throughout the game. Whenever I am in the scene where you "dive into" the Deathstar, I hit all four corners quickly so it re calibrates. Not sure if it works right then but I do think it does.


I've actually never looked closely between the difference before I start a game....

So was mine. I found the test screen to be of little help. And when I installed my ram controls repo controller I never need to calibrate it. Its perfect upon start up everytime. So for me, it was definitley a controller issue.
 
Good news!

It turned out that my Star Wars was not holding its settings in the 2212 static ram chip. The ESB was holding settings, but the SW was not.

I replaced the 2212 chip... and...

Now my SW boots up and the crosshair IS CENTERED!

So SW is definitely storing some calibration data in the static ram.

... Altan
 
Weird shit. Mark would know about that ?

Disappointed to say the problem has come back. Not sure what's going on. Perhaps it is not tied to the 2212 novram.

At least it's not a very big problem :)

... Altan

Note: see my later post that adds some info to this observation
 
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Disappointed to say the problem has come back. Not sure what's going on. Perhaps it is not tied to the 2212 novram.

At least it's not a very big problem :)

... Altan

I really don't think there's any problem... every one I've ever played has done that, and it does it in MAME.

DogP
 
When in doubt, you consult "the creator":

You might have noticed that the centering of the Star Wars control yoke is funny at times. Star Wars originally used a Pokey to read the pots. At that time, people either made their own A/D converter with a counter, a comparator, and a ramp, or they used Pokey. The Pokey was a full custom IC designed for the Atari 800/400 to read pots and keys, which gave it its name, POts and KEYs. There was some room left over so they put in some crude square wave sound generators as well as a UART. Unfortunately, Pokey does a really awful job of reading pots; it is guaranteed to produce occasional wrong values. The software to deal with it is pretty nasty. After Greg Rivera brought this to my attention I took the daring step of actually putting in a real A/D (Gasp!), the ADC-0809. Unfortunately, many people continued to use the original code to treat the A/D values as though they had come from a Pokey. Like Greg. That is why the Controller in Star Wars keeps getting recentered, usually badly.

This is taken from Jed Margolin's website, right here:
http://www.jmargolin.com/vgens/vgens.htm#Star

For those who don't know: Jed was the man behind the hardware of SW (and the actual game idea too).

Re-reading this, can someone hack out the unnecessary centering routines ? ;)



I am 99.9999% sure that no pot/yoke centering values are written to the NVRAM. That would wear it out very very quickly. Now, the NVRAM values are only changed when you change settings or when someone reaches the top 3 score.
 
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Level42,

Great info. I wasn't aware of Jed's site. I spent a bunch of time reading his info. I even dropped him a note. I haven't heard anything back yet.

Having said all that... I've got some evidence (not 100% solid, but some...) that indicates it may be related to NOVRAM.

I had an issue where SW would lose it's settings. I seem to have that resolved... it hasn't lost settings in 4 or 5 days. Keeping fingers cross. Each time I check to see if it has lost settings, I play a game. For all of these games, the crosshair has been pretty much centered from power up.

Below is a picture of what the crosshair looks like after powerup and starting a game. No movement of the yoke was performed.

P1020181.jpg


So I'm happy... no need to calibrate each time I power up. I cannot say it's related to NOVRAM... perhaps something else I changed made the difference. If I could only get MAME to compile on my mac, I could add a log message to the 2212 store logic and really see what happening. But I only spent 5 minutes on that (the project is based on an old Apple SDK that I don't have).

... Altan
 
Jed replied to 2 e-mails I sent him some years ago, took some time, but he did reply.

The X2212 is specced to last 100,000 write cycles.
If there are pot values stored in it, when would that happen ? If it would be a number of times per game, it wouldn't last very long I guess.... ?
 
The X2212 is specced to last 100,000 write cycles.
If there are pot values stored in it, when would that happen ? If it would be a number of times per game, it wouldn't last very long I guess.... ?

Totally agree... Just reporting what I am seeing :)

... Altan
 
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