Max number of digits supported - 8Segment Displays

Support for Arduino in combination with Air Manager and Air Player

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furballsim
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Max number of digits supported - 8Segment Displays

#1 Post by furballsim »

What are the maximum number of digits supported for 8 segment displays? I have 3 five digit units connected to the same segment lines. This works for my own code, written directly to the Arduino, however AirManager seems to top out at only 8 digits. Is this a hard limit?

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Sling
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Re: Max number of digits supported - 8Segment Displays

#2 Post by Sling »

In theory you could add each module separately if the limit is indeed 8. I’m not sure the limit is published anywhere but it would need to be limited because you can’t multiplex indefinitely. It seems 15 is doable from what you say. I’ve never personally tried more than about 8.

The problem with splitting them of course is it consumes a lot of pins. If you have several displays to make it would be better to use a MAX7219 which is natively supported or alternatively the TM1637/38 via message port.

furballsim
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Re: Max number of digits supported - 8Segment Displays

#3 Post by furballsim »

Looks like I may need to split them - pins aren't too much of an issue as they're plugged into a Mega. I have a couple of MAX7219s spare, however these are OpenCockpits modules, which are a better fit size wise. The other option, as you say, is to message port it. Thanks for your help.

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Ralph
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Re: Max number of digits supported - 8Segment Displays

#4 Post by Ralph »

There are some troubles with the MAX7219 at the moment, both in 3.x and 4.0. It's something we're gonna fix, but it'll be in 4.1 or 4.2. Corjan went all in with a oscilloscope to analyze the signals, and see what's going wrong. No progress yet I believe.

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