Double Digit 8 segment display query

[DDJ2011]

I'm interested in getting one of these and programming for it.

I've had a search in the forum but can't find anything. Has anyone used anything like this and can offer some advice?

Should I buy common cathode or common anode? Probably doesn't make a lot of difference in the final analysis I expect.

Thanks.

 

[nick12ab]

To drive these, you can use one of many different methods such as...

• Multiplexing
  • Uses least power
  • Requires one I/O pin per segment plus one I/O pin per digit
  • Makes displays a little bit dimmer
• Direct driving using larger PICAXE chip
  • uses one I/O pin per segment
  • Uses more power
  • May exceed total chip current limit
  • easy to implement
• Shift register driving
  • Uses most board space
  • Uses more power
  • Uses only 2~3 pins per digit
  • Reasonably easy to use
• Use a dedicated driver chip for multiplexing
  • Low power
  • Less flicker than PICAXE multiplexing
  • VERY expensive
  • Reasonably easy to use

 

[eclectic]

Also, have a look at
Manual 3, pages 21 - 23

and for general background, the Display driver section of

http://www.kpsec.freeuk.com/counting.htm#drivers

e

 

[booski]

When I used a pair of segment displays like that, I used a MAX 7219. I got 5 of them free samples from Maxim http://www.maxim-ic.com/datasheet/index.mvp/id/1339
They're really easy to interface to also and can use up to 8 displays from a single chip!

 

[westaust55]

For the shift register method mentioned by Nick12ab it is also possible to drive multiple digits with cascaded shift registers using only 3 Picaxe pins. I posted a project some time ago using this method for 3 digits.

Note there are other chips as mentioned above. Which can perform better

 

[DDJ2011]

Thanks for the suggestions everyone - lots of research to be done!

 

[Svejk]

Also, have a look on this thread for simple multiplexing 7 segment displays