MAX 7219 driver -- newbie question
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Posts: 46,084
OK, guys, bear with me as I am brand spankin' new to this, though I
have had some experience with IC circuits and such concerning model
trains.
I want to use the Stamp to control a MAX 7219 which will, in turn,
drive 32 sets of eight LEDs each. The Stamp will generate a random
number from 0 to 31, light the appropriate set of LEDs, then loop
back until a pushbutton is pressed, when it will then stop and keep
the last set of LEDs lit until another pushbutton is pressed. If
you've ever seen the old game show "Press Your Luck" or its latest
incarnation, "Whammy! The All New Press Your Luck," you know what
I'm going for here--it's a similar device for use in children's
church.
Anyway, my question: What is the best way for the MAX 2719 to handle
these LEDs? Should I two sets of four LEDs in series, then put those
two sets in parallel? If so, what current-limiting resistors do I
need and what would be the best supply voltage? I'm guessing a 12V
300ma power supply would do the trick. Or should I put one series of
four LEDs on one output and the other series on another (since I
have 64 to play with on the MAX 7219), and simply turn them both on
at the same time?
By the way, these are 10mm high-brightness LEDs, and I'm guessing
15ma should be sufficient, but can I go to 20ma with the two-series-
of-four method.
What's the best method? Schematics help, BTW.
Blessings!
Robert Carter
Garywood assembly of God, Birmingham, Alabama
have had some experience with IC circuits and such concerning model
trains.
I want to use the Stamp to control a MAX 7219 which will, in turn,
drive 32 sets of eight LEDs each. The Stamp will generate a random
number from 0 to 31, light the appropriate set of LEDs, then loop
back until a pushbutton is pressed, when it will then stop and keep
the last set of LEDs lit until another pushbutton is pressed. If
you've ever seen the old game show "Press Your Luck" or its latest
incarnation, "Whammy! The All New Press Your Luck," you know what
I'm going for here--it's a similar device for use in children's
church.
Anyway, my question: What is the best way for the MAX 2719 to handle
these LEDs? Should I two sets of four LEDs in series, then put those
two sets in parallel? If so, what current-limiting resistors do I
need and what would be the best supply voltage? I'm guessing a 12V
300ma power supply would do the trick. Or should I put one series of
four LEDs on one output and the other series on another (since I
have 64 to play with on the MAX 7219), and simply turn them both on
at the same time?
By the way, these are 10mm high-brightness LEDs, and I'm guessing
15ma should be sufficient, but can I go to 20ma with the two-series-
of-four method.
What's the best method? Schematics help, BTW.
Blessings!
Robert Carter
Garywood assembly of God, Birmingham, Alabama