Driving C/Cathode RGB LEDs with MAX7221?
is there way drive common cathode (4-pin) rgb leds max7221 chips?
(http://datasheets.maximintegrated.com/en/ds/max7219-max7221.pdf)
thanks
not really. @ none make sense. make table cross reference digit pins segment pins there no pattern it. chip designed common-cathode 7-segment displays segments connect led cathode , digit pins connect led anode. if in jam , had leds running chip take me hour make table , hour write sketch electronically doable.it has enough sink current you have calculate value current limit resistor connected iset.
warning: if iset pin-18 connect directly +vcc without resistor , power turned on destroy led connected between digit pins , segment pins in about
1 ms !
read section rset explaining how calculate resistor value. schematic on datasheet provides example reference.
your cross reference table should have digit pin numbers on left side of page , segment pin numbers across top. 2 intersect draw leds cathode toward digit pin , anode toward segment pin (because replacing segment led of common -cathode display.which has 7 segment cathodes & decimal point connected digit pin , anodes connected segment pins.)
you need clock signal , need load serial data in.
read pages 6 & 7 understand addressing , bit pattern.
don't forget read chip select/load pin too. that's how load data. @ waveforms.
it lot of detailed work.
if me use tlc5940 chip . that's pretty plug , play using library.
your question :
my answer yes. fun ? depends on whether enjoy doing things hard way.
it 10 mhz serial chip feel free use whatever clock want long not more 8 mhz. can devide 16 mhz
clock 2 clock.
since i'm such nice guy i'll throw bone...
http://playground.arduino.cc/main/ledmatrix
enjoy !
warning: if iset pin-18 connect directly +vcc without resistor , power turned on destroy led connected between digit pins , segment pins in about
1 ms !
read section rset explaining how calculate resistor value. schematic on datasheet provides example reference.
your cross reference table should have digit pin numbers on left side of page , segment pin numbers across top. 2 intersect draw leds cathode toward digit pin , anode toward segment pin (because replacing segment led of common -cathode display.which has 7 segment cathodes & decimal point connected digit pin , anodes connected segment pins.)
you need clock signal , need load serial data in.
read pages 6 & 7 understand addressing , bit pattern.
don't forget read chip select/load pin too. that's how load data. @ waveforms.
it lot of detailed work.
if me use tlc5940 chip . that's pretty plug , play using library.
your question :
quote
is there way drive common cathode (4-pin) rgb leds max7221 chips?
my answer yes. fun ? depends on whether enjoy doing things hard way.
it 10 mhz serial chip feel free use whatever clock want long not more 8 mhz. can devide 16 mhz
clock 2 clock.
since i'm such nice guy i'll throw bone...
http://playground.arduino.cc/main/ledmatrix
enjoy !
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