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Author Topic: AS1130 First attempt - working  (Read 21532 times)
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WAIT!
So you are saying I can choose which Gnd pin and which Vcc pin to use?  I don't need to connect all of them?
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Yep!  smiley-yell smiley-mr-green
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AWWWWWW I wish I knew that earlier
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They won't be floating...they are connected internally. smiley-razz
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Don't forget that the LEDs are being fed by a variable duty cycle.

I am using a 3.3V regulator fed from the 5V USB port (like on the Arduino) and the maximum current drawn by the AS1130 when all LEDS are on and at maximum brightness is about 245mA but this is only for a maximum 500mS as it then switches to the next frame.

I would allow 500mA per 11x12 panel..that should be more than enough (unless you have other stuff connected) 
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Are you a student by any chance?  smiley-mr-green

Look up Ohms law and read the datasheet.

Read about PWM duty cycles.

 smiley-twist
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 smiley-mr-green
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when the CURRENTSOURCE Register is 0xFF then every single led gets 30mA, so 132 x 30mA = 3,96mA no?

Ahhh but if you read the datasheet the LEDs are crossplexed and the scanning only turns on 1 Current Source at a time...

My board (as I said) draws 245mA when full on and it draws that for 487.5mS or a MAXIMUM of 500mS (it could be 32.5mS too but THAT would be the minimum time)

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THIS problem with the current is the last thing I have to know to build the circuit finally...

You are right to consider all angles before embarking on a design and building the prototype....but the datasheet gives all this information and you can trust it!
OR
You can trust the fact that I have one working and I have shared the information.

If you consider that 11 x 20mA LEDs  draw 220mA when full on and you have 3 boards then 3 x 220 = 660mA
Then you must add some for the chips themselves plus leakage, losses, blah blah blah....

I would design for a 1.5A supply to drive 3 boards and a MCU etc.



Now it's time to get the soldering iron out.... smiley-razz
« Last Edit: October 17, 2012, 10:01:21 am by Hexadec » Logged

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I'm really sorry that I'm still discussing with you
I don't have a problem with that...as long as you are prepared to put in the effort to understand.... smiley-mr-green

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What do you mean with '1 Current Source'?
There are 12 Current Sources CS0 - CS11.

Try to forget about crossplexing and charlieplexing for a moment and think about how a matrix of LEDs is scanned.
Here is a good explanation of how it works: http://www.franksworkshop.com.au/Electronics/RGB/RGB.htm

This means that it is only possible for there to be 11 LEDs on at any one time. (in this case)
Then... we take into account that each LED is also PWM driven (you can look that one up yourself  smiley-razz)

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But in your first programm the current source register is 0xFF so 30mA per Led, and then you have 330mA and not 235?

The current source register is not setting the amount of current drawn by each LED it is setting the maximum possible current that CAN be drawn (allowing dimming of the display)
The amount of current drawn is determined by the circuit characteristics but is LIMITED to a MAXIMUM of 30mA by the CS Register.

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But if the Current Source Register is 0xFF then all the LEDs together draw 11x30mA so 330mA and that three times (three screens) so 990mA!
Wrong!

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Isn't there any solution to have max. 500mA for the three screens together?
Yes.
The obvious way is to use LEDs that draw less current....if you can find them.
OR easier
Limit the current in the Current Source Register to 15mA (0x0F) but you'll have to make sure in software that this doesn't change.
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Like I said earlier...read the datasheet, use Ohms law and believe the datasheet (usually)  smiley-mr-green
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Okay as I understand the PWM is responsible for the brightness (if they shine bright or dark) and because of that the leds need more or less current.And if I want now to know the current of every single led then I use that formula on the page 33 'LED Current Calculation' ?
But if I only use that formula...then the fact that the other chips also need current is ignored?  cause you told this: "Then you must add some for the chips themselves plus leakage, losses, blah blah blah...."

Read the datasheets.  smiley-roll-blue

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How can I be sure that the current of the LEDs is never too high that they burn? If I set the Current Source register the same value as the IMAX of the led?

Ohms Law...and why ask me to answer a question I have already answered in full?

Quote
I found some 10mA leds like these: (I want to use square leds, they look much cooler smiley-wink): http://www.eled.com/category.asp?catalog_name=leds&category_name=single+color+-+square+led&page=1
There is written IF=10mA, but if you open the datasheet there is written 20mA! So are those leds now 10mA or 20mA for IF?Could I use them?

Do you want me to email the supplier for you and ask them if their description or the datasheet is correct? smiley-roll-blue
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So I don't believe this question has been asked.  Hexadec, would you happen to know how the programming would change if you were to have another chip in there?  Using the sync and everything?

Also they mention a adjustable clock out frequency,  would you happen to know anything about that?  Its on their table 25 on page 27 of the datasheet.
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mornin' funky  smiley-mr-green(well it is here anyway)

As you know, for some reason I haven't yet discovered, I can't get any response on the IRQ line so I haven't done anything yet with multiple screens.

That said, you have several options for generating interrupts.

If, for instance, you want to scroll across 2 LED matrices I would think that you would set the first AS1130 (the one that generates the sync clock) to interrupt after the last frame. Then the controlling processor tells the next AS1130 to start scrolling. When it has displayed its last frame it sends an IRQ and the cycle repeats.

As for the programmable clock out freq., it's fairly clear that the sync frequency can be altered to 1 of 4 speeds but I have no idea if this changes the frequency of the internal clock of the 'master' chip as well as the sync out line. I'll do some research when I get a bit of free time.  smiley
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good morning! (afternoon now, it was a long night  smiley-evil )

Yea, I've been looking over the datasheet and I can't quite understand what they are trying to say with the clock speed dealio.
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Yeah...the whole datasheet is a bit difficult...there is no overview and the typical application diagrams are next to useless.

Oh well...at least it's been written by someone with a reasonably good command of English and it's not translated by Google from the original Thai dialect... smiley-mr-green smiley-mr-green

As soon as I get some time I'll be building a big board with 4 panels so the fun will REALLY start then.  smiley-sweat
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wait wait wait wait,  you have access to all that?  How much does that cost you?
(I've been looking for a cheaper way of fabrication but b/c I'm a student, I can't do much)
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