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Justplayin

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Joined: 31/01/2014
Location: United States
Posts: 330

Posted: 09:44am 23 Sep 2015

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I'm trying to figure out a way to connect a large string of the 8x8 LED matrix modules. Problem is the SPI connection fails after about 8 modules daisy chained together. Any suggestions what would might work as a signal booster/repeater/buffer/driver (pick your terminology)? I'm looking at connect about 28 modules to start with.

Thanks,
Curtis

I am not a Mad Scientist... It makes me happy inventing new ways to take over the world!!

matherp
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Joined: 11/12/2012
Location: United Kingdom
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Posted: 10:10am 23 Sep 2015

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Try one of these or just duplicate mosfet circuit but use the same voltage on each sideEdited by matherp 2015-09-24

Justplayin

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Joined: 31/01/2014
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Posts: 330

Posted: 10:18am 23 Sep 2015

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Thanks for the suggestion! I bought some of those awhile back and never used them. I'll give it a try. All I have to do now is find them!

--Curtis

I am not a Mad Scientist... It makes me happy inventing new ways to take over the world!!

bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2956

Posted: 04:52pm 23 Sep 2015

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Hi Peter, Curtis,

matherp said Try one of these or just duplicate mosfet circuit but use the same voltage on each side

HaHa I just emailed Curtis this morning with exactly the same device..

What do they say about great minds??

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

bigmik

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Posted: 04:57pm 23 Sep 2015

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Curtis,

You would only need one of these I reckon as the Din is cascading through the Max7219 so should effectively be boosted/buffered EVERY module... The CS and CLK signals are paralleled so would need the buffer.

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<

Justplayin

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Joined: 31/01/2014
Location: United States
Posts: 330

Posted: 07:13pm 23 Sep 2015

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bigmik said You would only need one of these I reckon as the Din is cascading through the Max7219 so should effectively be boosted/buffered EVERY module... The CS and CLK signals are paralleled so would need the buffer.

I tried the one converter I had immediately on hand and had moderate success with 12 modules. Looked great when it was working! But, in the end my setup was still unstable. There are some issues I need to address such as I had everything plugged into a cheap breadboard, was using lots of crappy jumper wires and the converter had some really long leads already soldered om to it. I'm going to try again after I find my other converters and set the whole thing up a little more "in-line". If needed, I don't mind using a couple set of converters to boost the signals along, they're cheap.

--Curtis

I am not a Mad Scientist... It makes me happy inventing new ways to take over the world!!

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