My IPac LEDS are inverted!!?

[Brad Lee]

Here's how Ive got it hooked up:

In each switch, the vertical contacts on the left side are for the LED, and on the right, the outside pair is for NO, the inside pair is NC. Gray is for the ground, all chained together. Red is for the connection, as follows

Switch one to start 1
Switch 2 to start 2
switch 1 led to player 1 button 7
switch 2 led to player 1 button 8


Both leds are constantly ON, on my keyboard, they both show as OFF
Load up asteroids 'cuz I know it uses the same start buttons
Insert 1 coin, the P2led(on the right) starts to blink, P1 stays ON, and the keyboard num lock also starts blinking
Add another coin and both leds start to blink, on the keyboard, caplock starts to blink also
If I start a 1 player game, the P1 led lites up and P2 goes out, likewise if I start 2 players, P2 lites and P1 goes out

What the heck is going on?

[Tiger-Heli]

Here's how Ive got it hooked up:

In each switch, the vertical contacts on the left side are for the LED, and on the right, the outside pair is for NO, the inside pair is NC. Gray is for the ground, all chained together. Red is for the connection, as follows

Switch one to start 1
Switch 2 to start 2
switch 1 led to player 1 button 7
switch 2 led to player 1 button 8


Both leds are constantly ON, on my keyboard, they both show as OFF
Load up asteroids 'cuz I know it uses the same start buttons
Insert 1 coin, the P2led(on the right) starts to blink, P1 stays ON, and the keyboard num lock also starts blinking
Add another coin and both leds start to blink, on the keyboard, caplock starts to blink also
If I start a 1 player game, the P1 led lites up and P2 goes out, likewise if I start 2 players, P2 lites and P1 goes out

What the heck is going on?

It's not very clear on Andy's site, but the LED's need a +5V input, and I think you also picked the wrong terminals.

I'm pretty sure the way to hook them up is:

Num Lock - P1 Start

Wire 1 from +5V lead of 10-pin terminal of I-PAC (or +5V on computer) to long lead of LED.

Wire 2 from short lead on LED to P1B7 terminal of I-PAC.

Caps Lock - P2 Start

Wire 1 from +5V lead of 10-pin terminal of I-PAC (or +5V on computer) to long lead of LED.

Wire 2 from short lead on LED to P2B7 terminal of I-PAC.

Scroll Lock -

Wire 1 from +5V lead of 10-pin terminal of I-PAC (or +5V on computer) to long lead of LED.

Wire 2 from short lead on LED to P1B8 terminal of I-PAC.

See http://www.ultimarc.com/ipac2.html for the location of the +5V outputs on the I-PAC 10-pin header.

[Brad Lee]

Yeah I realized I had the wrong order after re-reading  (p1b7,p2b7,p1b8)

So how you understand it is instead of going to a common ground, they should go to the 5v.. I'll give it a try tonight, got nothin to lose


As an aside, will there ever be support for a 4th led? I realize for most users it'd be useless as they only have 3 lock Leds, but for a truly authentic Omega Race there should be 4. Just something I'd wondered

[SirPoonga]

Ther are games iwth even more lights, so it probably won;t happen as keyboards generally have only 3 leds and is easy to make those blink.

[Odonadon]

This reminds me - Obviously Capslock is for P1 coin door, Capslock is for P2, what would scroll lock be for?  I'm wondering where to place the 3rd LED.  Or should I not hook any of them up to the coin door lights?

Thanks,
Odonadon

[Howard_Casto]

There are variious uses for leds on arcade games... skill level in daphne games used leds, for example.... Also remember that there are 3 player games.... Rampage's coin lights flashed when you put in a quarter if i remember correctly.  

[Odonadon]

There are variious uses for leds on arcade games... skill level in daphne games used leds, for example.... Also remember that there are 3 player games.... Rampage's coin lights flashed when you put in a quarter if i remember correctly.

But on the whole, if one was to place the LEDs from the iPac somewhere on the cab, where would be the best place to put 'em  I wa splanning on hooking Numlcok to P1 coin light, and Caps lock to P2 cound light, but was at a loss as to where the Scroll Lock LED would go best.  This would obviously be a MAME specific thing.

Thanks,
Odonadon

[JustMichael]

Tiger-Heli,

Actually the picture on the Ultimarc site is very clear.  You hook up a resistor to the 5V suppy on the 10pin header.  Then you hook the resistor to the led and then hook the other leg of the led to either the scroll lock, number lock or caps lock pin on the 10pin header.  Andy even includes the suggestion of using 220 ohm resistors.

[Brad Lee]

Hooray for me, I finally got things working right

I already have a free molex connector that I'm stealing 12v for the coin door lights, so I just tapped into the red 5v line for both leds

P2 button 7 did light scroll lock, so that'd be player 3's light
P1 button 7 lit numlock, for player 1
P1 button 8 lit caps lock player 2

[Tiger-Heli]

Tiger-Heli,

Actually the picture on the Ultimarc site is very clear.  You hook up a resistor to the 5V suppy on the 10pin header.  Then you hook the resistor to the led and then hook the other leg of the led to either the scroll lock, number lock or caps lock pin on the 10pin header.  Andy even includes the suggestion of using 220 ohm resistors.

I agree the picture for hooking up the LED's using the 10-pin header is very clear.

Brad Lee was hooking the LED's up using the bi-directional P1B7, P2B7, and P1B8 inputs.  Andy's site only briefly mentions these connections as follows:

LEDs: The three LEDs use the following inputs, which become bdirectional:
Player 1 Button 7
Player 2 button 7
Player 1 button 8
These inputs can still be used for buttons even if LEDs are connected but note that when the buttons are pressed the LEDs will light. You can wire your own LEDs to these connections.

There is no mention of needing to connect the LED's between +5V and the button input (Andy confirmed this to me by E-mail, but I didn't pick it up originally).

There is also no mention of which LED is controlled by each input (thanks Brad Lee for posting).  I incorrectly assumed that P1B7 was NumLock and P2B7 was Caps Lock since that's the order they're listed on Andy's page.

Now I have to re-work all my plan's to pick up the different button assignments!  ARRRRRRGH!!!  (Oh well, that's the consequences of planning without having hardware in hand.)

BTW, I have great respect for both you and Andy and this isn't meant as a criticism, I just want to point out that this particular item should be better documented.

[Chris]

There are variious uses for leds on arcade games... skill level in daphne games used leds, for example.... Also remember that there are 3 player games.... Rampage's coin lights flashed when you put in a quarter if i remember correctly.

But on the whole, if one was to place the LEDs from the iPac somewhere on the cab, where would be the best place to put 'em  I wa splanning on hooking Numlcok to P1 coin light, and Caps lock to P2 cound light, but was at a loss as to where the Scroll Lock LED would go best.  This would obviously be a MAME specific thing.

Thanks,
Odonadon

Mine are below the P1 and P2 start buttons; they're in Radio Shack chrome LED holders, which gives them a vague volcano button look.  I didn't use the Scroll Lock LED.  Don't forget your resistors!

[Odonadon]

Mine are below the P1 and P2 start buttons; they're in Radio Shack chrome LED holders, which gives them a vague volcano button look.  I didn't use the Scroll Lock LED.  Don't forget your resistors!

So you have both coin door lights AND the iPac LEDs mounted on the front?  And what do you mean about the resistors?

Odoandon

[Chris]

No, my coin door lights are just wired to the PC's power supply, so they are on steady all the time.  When you attach LED's to the IPac, you need to wire a resistor (say, 220 ohms or so) in series with the LED, or you'll fry it.

I'm actually using a keyboard hack, not an IPac, so my LED output already has the correct resistance....



220 ohm resistors should be available at your local Radio Shack.

[Brad Lee]

Couple weird things Ive noticed

Sometimes when I add a 2nd quarter to asteroids, the leds blink on the same cycle, sometimes they blink alternating. Is this some weird mame timing issue, or arcade accurate?

Also, using Advmenu and command line Mame, exiting a game doesnt restore the leds to an "off" state. Mame32 does this and Ive come acros the code for it, so Im gonna look and see if its something in the mame code, or for the gui itself that handles this

[OSCAR]

Couple weird things Ive noticed

Sometimes when I add a 2nd quarter to asteroids, the leds blink on the same cycle, sometimes they blink alternating. Is this some weird mame timing issue, or arcade accurate?

Also, using Advmenu and command line Mame, exiting a game doesnt restore the leds to an "off" state. Mame32 does this and Ive come acros the code for it, so Im gonna look and see if its something in the mame code, or for the gui itself that handles this

Do you happen to have a keyboard plugged into the pass-thru on the IPAC?  I noticed the same kind of funkiness like you describe, but it only happened when I had a keyboard on the pass-thru.  And to add another variable to the mix... it didn't do this when I had a different motherboard.  Perhaps a weird combination of keyboard pass-thru/motherboard bios can cause this, I don't know?  I could be way off on this one, I just happened to notice this same thing before, too...

[Howard_Casto]

The leds on your primary keyboard and secondary keyboard cancel out each other..... Like if you were playing mame and pressed the caps lock on your keyboard it would override any flashing on your ipac's leds.  It also seems that the leds on your keyboard get resetted upon exiting mame instead of the ipac.  
Very strange I know, but considering the keyboard port is used to handling 3 leds instead of 6 it's very understandable.  

 

[Odonadon]

When you attach LED's to the IPac, you need to wire a resistor (say, 220 ohms or so) in series with the LED, or you'll fry it.

Really?  I don't remember seeing anything about that on Ultimarc.com, thought I notice that's where you got the image from.  Why wasn't the resistor inclued in the LED harness then?  That's very odd.

Odonadon

[Brad Lee]

After a few..dozen games of Asteroids, I've succeeded in burning out one of the Leds. I think I'll try a PC battery(3v) as my power source at least until I pull these out, get a new led and install all 4, with proper resistors and all.

As far as my reading goes, the LED harness from ultimarc does have the resistors, odonadon

[Tiger-Heli]

When you attach LED's to the IPac, you need to wire a resistor (say, 220 ohms or so) in series with the LED, or you'll fry it.

Really?  I don't remember seeing anything about that on Ultimarc.com, thought I notice that's where you got the image from.  Why wasn't the resistor inclued in the LED harness then?  That's very odd.

Odonadon

The image is easiest to find if you click on "Site Map" and then "I-PAC - Installation".

The Ultimarc harness either has the resistors built in, or uses higher voltage LED's.  You only need the resistors if you are using your own LED's without the harness.  And for that matter:

The I-PAC supplies +5V to the LED driver output.  LED's are available in +12V (fairly common), +5V (hard to find), and 2.1 V (most commonly).  This will be reffered to as V (typical), V (max), or Vf on a spec chart.

12V led's probably won't work as the +5V signal won't bias the LED (or if they do work, they will be rather dim)

5V LED's work perfectly without a resistor.  Radio Shack had them in their stores (P/N 276-208 in Red) for $0.99, but they discontinued them.  www.digikey.com has them (last I checked) (P/N MR3050QT-ND (Red) MR3450QT-ND (Green) or MR3350QT-ND (Yellow)) for about $0.62 cents each, but they tack on an additional $5 shipping for orders under $25.

Or you use 2.1V LED's with a 220-ohm resitor to cut the I-PAC's 5V output down to 2.1V so you don't burn up the LED.

Hope this helps!

[Chris]

The resistor isn't just to reduce the voltage!  LED's offer practically no load; if there is no other load on the circuit, the current draw will be near infinite (Ohm's law). Thus, snap, crackle, pop!

Most LEDs have their characteristics specified at a current of 20 mA. If you want really good reliability and you are not certain you don't have worse-than-average heat conductivity in your mounting, heat buildup in wherever you mount them, voltage/current variations, etc. then design for 15 milliamps.

Now for how to make 15 milliamps flow through the LED:

First you need to know the LED voltage drop. It is safe enough to assume 1.7 volts for non-high-brightness red, 1.9 volts for high-brightness, high-efficiency and low-current red, and 2 volts for orange and yellow, and 2.1 volts for green. Assume 3.4 volts for bright white, bright non-yellowish green, and most blue types. Assume 4.6 volts for 430 nM bright blue types such as Everbright and Radio Shack. Design for 12 milliamps for the 3.4 volt types and 10 milliamps for the 430 nM blue.

You can design for higher current if you are adventurous or you know you will have a good lack of heat buildup. In such a case, design for 25 mA for the types with voltage near 2 volts, 18 mA for the 3.4 volt types, and 15 mA for the 430 nM blue.

Meet or exceed the maximum rated current of the LED only under favorable conditions of lack of heat buildup. Some LED current ratings assume some really favorable test conditions - such as being surrounded by air no warmer than 25 degrees Celsius and some decent thermal conduction from where the leads are mounted. Running the LED at specified laboratory conditions used for maximum current rating will make it lose half its light output after rated life expectancy (20,000 to 100,000 hours) - optimistically! You can use somewhat higher currents if you heat-sink the leads and/or can tolerate much shorter life expectancy.

Next, know your supply voltage.  It should be well above the LED voltage for reliable, stable LED operation. For an IPac or keyboard hack, this is almost certainly 5 volts.  Use at least 3 volts for the lower voltage types, 4.5 volts for the 3.4 volt types, and 6 volts for the 430 nM blue.  (Darn... I really wanted to use blue LED's on my panel!)

Next step is to subtract the LED voltage from the supply voltage. This gives you the voltage that must be dropped by the dropping resistor. Example: 3.4 volt LED with a 5 volt supply voltage. Subtracting these gives 1.6 volts to be dropped by the dropping resistor.

The next step is to divide the dropped voltage by the LED current to get the value of the dropping resistor. If you divide volts by amps, you get the resistor value in ohms. If you divide volts by milliamps, you get the resistor value in kilo-ohms or k.

Example: 5 volt supply, 3.4 volt LED, 12 milliamps. Divide 1.6 by .012. This gives 133.33 ohms. The nearest standard resistor value is 150 ohms.

If you want to operate the 3.4 volt LED from a 5 volt power supply at the LED's "typical" current of 20 mA, then 1.6 divided by .02 yields a resistor value of 80 ohms. The next highest standard value is 82 ohms, but 100 ohms will be more common.

If you want to run a typical 3.4 volt LED from a 5 volt supply at its maximum rated current of 30 mA, then divide 1.6 by .03. This indicates 53 ohms. The next higher popular standard resistor value is 56 ohms. Please beware that the 30 mA rating for 3.4-3.5 volt LEDs may be optimistic.

One more thing to do is to check the resistor wattage. Multiply the dropped voltage by the LED current to get the wattage being dissipated in the resistor. Example: 1.6 volts times .03 amp (30 milliamps) is .048 watt. For good reliability, it is recommended not exceeding 60 percent of the wattage rating of the resistor. A 1/4 watt resistor can easily handle .048 watt. In case you need a more powerful resistor, there are 1/2 watt resistors widely available in the popular values.

(Adapted from LEDs 101 at http://misty.com/people/don/ledd.html)

--Chris

[Tiger-Heli]

The resistor isn't just to reduce the voltage!  LED's offer practically no load; if there is no other load on the circuit, the current draw will be near infinite (Ohm's law). Thus, snap, crackle, pop! - snip-

WoW, Chris!!!!, well said!   Thanks for the excellent info.

[Odonadon]

Thanks Chris!

So for those of us who don't know what in the world you just said, I basically need to replace my iPac harness LEDs with 5v ones, as that's what they're designed for?  I don't need to put any resistors in the circuit, unless going with something lower than 5v?

Say I want the brightest white LEDs possible, and don't want them to burn out for a very long time.  Radio Shack should have what I'm looking for?

Then there's still the question as to why I bought the harness in the first place as it seems essentially useless ...

Thanks,
Odonadon

[Chris]

I do not know what's in the harness, as I am using a keyboard hack.  If they provide you with a harness complete with LED's, you can safely assume they have proper resistance. (Note that some LED's have integrated resistors, so you may not see actual resistors in the harness.) However, if you plan to replace those LEDs with something brighter, you will probably need different resistors, and it's worth noting that white or blue LEDs are usualy higher voltage than red LEDs.

Yes, Radio Shack does have white high-brightness LEDs.  Look at http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F010%5F012%5F002%5F009&product%5Fid=276%2D320 .  These are 3.6 volts, maxing out at 20 mA, so shoot for no more than 15 mA.  Your supply is 5 volts, so you're dropping 1.4 volts.  Thus, you want to use at least 100 ohm resistors.  If you just swap out the Ultimarc LEDs with the white ones, they'll work, but they won't be as bright as you expect.  Still brighter than the stock LEDs though, and with less risk of heat problems than if you shot for 15 mA current draw.

Please note that I am not an expert in this field; I am not responsible if your LEDs, panel, or cat blows up.

--Chris

[OSCAR]

Then there's still the question as to why I bought the harness in the first place as it seems essentially useless ...

Ultimarc's LED harness do have the integrated resistors, just in case you were still unsure.  The above-mentioned advice & comments regarding adding resistors is for "off the shelf" panel-mount or board-mount LEDS.

I've used the www.mouser.com part # 35ca002 LED's with the I-PAC, and they work just fine.  These are actually 6V LED's with a chrome bezel & integrated resistor.  They are just the right brightness for a control panel;  not blinding, but not too dim either.  And at only $1.36 each, they priced pretty attractively, too.

Here's a couple of photos that compare the Atari cp LED's to the Mouser LED's:








As you can see, the Mouser LED's are a pretty close match to the Atari buttons in terms of brightness, and they will also give a nice appearance a control panel with the chrome bezel.    If anyone is looking for a no-brainer solution that will connect directly the I-PAC for a couple of LED's, then these Mouser's would be worth considering.


Here's the spec sheet:  http://www.mouser.com//catalog/specsheets/093550.pdf

Oh, and Mouser doesn't have a minimum order or handling charges...