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Topic: Where to start with multiplexing? or bit addressing? (Read 7674 times) previous topic - next topic

CrossRoads

Here's a 1x80 strip using shift registers.

Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

xl97

Thanks Grumpy_Mike and CrossRoads-

the bitmath link was a nice read..

and thanks for the diagram CR..  (a bit over my head.. but looking at those schematics arent as scary as they used to be!..  used to be they were so 'busy' it was a HUGE turn off and very demotivating.. now I can sorta follow..just dont always understand hat is being done on some things or need verification on what a certain trace is going or what part is what)


I found this:
http://arduino.cc/playground/Main/MAX72XXHardware

one chip..can drive 64 leds...etc

(again sorry Im 'so' bad at hardware)

I understand a 'driver' is just a board/chip that 'drives' the led(s) with the correct power.. right?  nothing more?
So that 'driver' linked above would be used only for supply enough power to my SMD leds.. (whatever the final count ends up being).. Id use or two of those chips..etc

however I still need to use/find a shift register.. (cause these are NOT the same..right?.. that driver chips can do shift register stuff?


I think Im still getting confused on the led strip.. vs a 'matrix'  (which I understand uses columns/rows to target the specific led)

and I read the article that using a 8 bit array to turn on/off leds  01100010  (direct bit addressing..etc)

but Im missing a real world example to put it all together.. even on a small scale.

Would I search here for bit math? or bit addressing? to see others experiences before me?  maybe seem some small diagrams/examples..etc



@CR-

dang.. thats a serious schematic for a noob to take in!  LOL


CrossRoads

Max 7221 is a nice chip, I use it to drive eight 7-segment displays here.
Has built in multiplex/control register. You do an SPI transfer to a byte, the 1's in that byte light up the matching LEDs.

Schematic is not tough - just 8 of the same thing. 3 control lines in, power, ground, couple of static lines, and the 8 LEDs. Don't let it get to you.

(shot across the length of my house, about 30') Digits are ~40mm x 80mm.


Here''s the '7219 & wiring to headers, parallel cable to the digit boards. Use a yellow highlighter to show what you have connected as you go.



The empty looking sockets on the middle board are the socket strips I used as headers. Got a duemilaove temporarily wired in here while waiting for a promini to arrive:
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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