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Guest PoRrEkE

How to have leds from 7seg. lit by own uncontrolled circuit ?

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I got here my Photon interface and Kingston LED displays. The idea is to save up as much space (led displays) on the output boards as possible so that I have aprox. 40 single leds available to control.This means I will have to wire up all the leading

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Philippe,Instead of wiring the leading digit as a numeric display, wire it as an LED. That will save you output ports.The numeric display segments act just like and LED. Turn on the display test feature. As you go through the output ports, each individual segment of the displays will light. You could light two segments for the number one and six segments for zero.Not exactly what you were asking for but this might help.Richard

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That is exactly what my plan was ;) ( only in other words :( )That's what I mean with "hard wire" some leds from a led display.I made the count and for 1(nav) 1(navsby) 1(com) 1(comsby) (alt)00Might have forgotten some but this ends up with 20 leds (from the led displays not hoocked up to the interface) that must be illuminated "by default".Now all I need to know is: where do I put resistors, which ones, do I take 5V or 12V power from the suply ?

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You might want to ask Scott, but from what I remember, the Output Module has the resister built into the controller chip.Also, I don't believe you can connect LEDs in series. The anode/cathode connections won't allow it.Richard

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Phillipe!I am no electronics wizard! but I am learning.I have some Kingbright LED's common cathode, as a test purpose I have taken two 1.5v batteries giving 3v output, this is which most leds work off, I took +3v to the input on the led, and from each segment took a wire that I can ground depending which segment I want lit.You want to use a PSU, this is my plan, so use the 5v wire but use a resister to drop the voltage to around 3v, I can work this out if you need and then you can make any digit you require, look at opencockpits site, they explain this better.Heres a pic to show it works!Regards Steve

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here's what I thought to do.I got a mail from Mike saying also I need a 280ohm resistor. He sais I need at least 150ohm and to get the brightness of the led correct compared to the other displays wired to Photon here's what I think of doing:1 wire to each led from the displays a 150ohm resistor. Folowed by a 1K trimmer. This way when I set the trimmer to 0, it won't kill the led in the display cuz I still got 150 ohm. But then I am able to increase the resistance of the trimmer such that the luminosity of the led becomes equal to those of the photon powered display leds.Anyone can confirm that this is a good way to do this ?

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>I got here my Photon interface and Kingston LED displays. >The idea is to save up as much space (led displays) on the>output boards as possible so that I have aprox. 40 single leds>available to control.>Can anyone make me a circuitry diagram on how to wire these up>and most important which resistors to use ? Also what I chose>12V or 5V ?Since everything else uses 5V, use 5V for the single segments as well.Put the resistors between +5V and the anode side of each segment.You'll need the same number of resistors as the number of segments/LEDs you want to control outside of photon.Here's a small ASCII diagram:+5V o---o-Resistor-o----o-segment1anode-displaycommoncathode-o---o GND+5V o---o-Resistor-o----o-segment2anode-/+5V o---o-Resistor-o----o-segment3anode-/The resistor value depends... I usually use 330 Ohms for 5V.However, since the MAX chips used in photon multiplex the displays AFAIK, the brightness of the segments controlled by photon will probably be less than those hooked up directly via resistors.You can try to work around the brightness difference by testing different resistor values. I'd say work your way up from 270 to whatever fits best. (Thats where a well sorted electronics parts collection comes in handy :)I'm not sure if its worth controlling some segments manually though.The brightness difference could be aesthetically disturbing.(that was one reason why I redesigned my PHCC display controller. The new one is so much better, no more brightness differences)Manuel

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Thnx for confirming my ideas.So would the plan to use a resistor and a trimmer in serie be a good idea then ?And should I take the 270 together with a 1K trimmer or the 150 as Mike suggested ?I just need the 1 fixed resistor to be there as safety. So I guess 270 might be the best plan.I'll go get a 270 and a 1K trimmer as soon as I can and give it a try. If that would happen to be not bright enough I could change it to a 150. (doubt it though)Either way, I think remember seeing in the SDK from Photon that I can control brightness of the leds via my software ... that might be something to play with as well...

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Philippe go here and download Fidocad 0.96.After installing, cut&past all the code below in Fidocad: just highilight it here, copy, and hit paste in fidocad.You'll see my schematics.[FIDOCAD]MC 105 30 0 0 220MC 105 40 0 0 220MC 105 50 0 0 220MC 105 60 0 0 220MC 105 20 0 0 220MC 105 10 0 0 220LI 105 60 105 10MC 90 5 0 0 080LI 105 10 105 5LI 105 5 100 5LI 120 65 120 10MC 105 75 0 0 420LI 90 20 90 5LI 90 85 120 85MC 90 20 2 0 010LI 90 85 90 85MC 90 85 2 0 020MC 70 70 2 0 000LI 70 70 90 70LI 90 70 95 75LI 95 75 105 75TY 45 60 5 3 0 0 0 * Power On SignalTY 130 75 5 3 0 0 0 * MOS (like the TIP121 or anything alike)This is just a very basic scheme as to how to wire multiple leds to one single control.Pay attention to the fact that depending on the MOS you find/buy, it may be active low or active high (P MOS or N MOS)The one shown in the scheme is a PMOS, as to say active high.This is basically a commanded switch to ground: when you set the relative command signal to high, the switches closes connecting all the leds to ground, thus makeing them light up.Ask if you need more info.

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Absolutely, see if you can find a lower trimmer, 1k is a bit too much.

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Thnx, I'll try to print this out and write your coments with it on a paper. Maybe one day I'll do it this way. First I'll just make them light up with my PSU. I got other stuff to pay for and to build first ;)I want to be flying now as soon as possible. Fairly made it unpossible now again by wrecking my current yoke.As explaind in an other topic I am going to be using bike-front-weel-axis to construct a linked 2 yokes system. Other than that I need to rebuild my shell so that my Overhead panel gets back into place. I can't wire it up when it sits across the room :( I refuse to use 6m of flat-cable ! haha.And for the leds, I'll first make my software going and have the digits going correct with the Photon. I can imagine the leading 1's and the closing 00's for a while.Thnx!

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have you ever set up an altitude in the AP like 32854 feet ?thos are the 2 "closing zeros" I mean.

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32854 feet... Hmm... Might try that :( If it works I'll post pics!Surely you can set it up in FSBus to increment in 1's and not 100's though? Might give the sim a heart attack....

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Today I went shopping for electro parts.I bought 20 resistors (150ohm) and 20 cheap trimmers (500ohm).I now got the 2 leds to form a "1" character from one of the displays wired up together to a 150 in series with the trimmer. When I set the trimmer almost open, the 1 appears same brightness level as the other leds. So I'll end up with 10 of both type resistors spare. It works when I take them 2 by 2 so .. why not.Also I got my program working for Photon. I got the output cards 1 and 3 confirmed and checked. They work as they should. 1 shows the XPDR and the COM1, 3 shows the NAV1 and NAV1 standby.Now it's down to getting the AP Alt on the 4th card and the COM1 standby and ADF on the 2nd card.I hope to hear from Scott soon on how to write my code to read the key input card cuz all I get now is runtime errors.. So I'm doing something wrong in my code, that's for sure.I'll post some pics on my weblog tonight. With some text in dutch but you guys will just have to ignore that :( I'll update my official website (engl.) soon I hope. Exams are finished now so maybe I'll have some time for that soon.Thnx for all the help on the "hard wiring" of the leds !

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