- Tue Nov 02, 2010 8:21 pm
#112663
Hello
I'm doing a project that's kind of a Monome variation. There's a "logic board" (essentially a modified Monome Arduino shield I found online) controlled by an Arduino that reads two separate 4 x 4 SparkFun button pads each of which have 16 LEDs (buttons read with 74164 and 74165 shift registers and LEDs controlled by a MAX 7219).
My breadboard prototype worked like a charm. After all hooking up two shift registers and a MAX 7219 to an Arduino isn't that complicated and it's well documented online.
However when I moved from my breadboard prototype to a proper prototype I encountered a problem. The SparkFun 4 x 4 breakout boards have 6 4-way connectors to connect to the outside world but I wanted to use a neater solution - a single 16-way ribbon cable. So I created an "adaptor board" that takes the connections (only need 16 as not using tri-colour LEDs) and leads them to a 16-way header. The board is L-shaped and sits directly beneath the breakout boards with 4-way connectors soldered into the 4-way holes in the breakout.
The result? Total weirdness! Some buttons will light the wrong LED. Others are fine. Others still will cause a weird cycling effect where a sequence of LEDs lights begin and repeat!
Given that
* I've quadruple checked for shorts and other gremlins on all three components (logic, adaptor, breakout)
* I had a test breakout board that didn't use my adaptor board but instead just soldered jumpers directly from breakout to logic board (ie no adaptor) and it worked absolutely fine
then what gives?
Is it possible that some kind of interference is going on between the breakout board and my adaptor board? It is soldered directly to it with only a 2-3 mm clearance between the two.
Thanks
I'm doing a project that's kind of a Monome variation. There's a "logic board" (essentially a modified Monome Arduino shield I found online) controlled by an Arduino that reads two separate 4 x 4 SparkFun button pads each of which have 16 LEDs (buttons read with 74164 and 74165 shift registers and LEDs controlled by a MAX 7219).
My breadboard prototype worked like a charm. After all hooking up two shift registers and a MAX 7219 to an Arduino isn't that complicated and it's well documented online.
However when I moved from my breadboard prototype to a proper prototype I encountered a problem. The SparkFun 4 x 4 breakout boards have 6 4-way connectors to connect to the outside world but I wanted to use a neater solution - a single 16-way ribbon cable. So I created an "adaptor board" that takes the connections (only need 16 as not using tri-colour LEDs) and leads them to a 16-way header. The board is L-shaped and sits directly beneath the breakout boards with 4-way connectors soldered into the 4-way holes in the breakout.
The result? Total weirdness! Some buttons will light the wrong LED. Others are fine. Others still will cause a weird cycling effect where a sequence of LEDs lights begin and repeat!
Given that
* I've quadruple checked for shorts and other gremlins on all three components (logic, adaptor, breakout)
* I had a test breakout board that didn't use my adaptor board but instead just soldered jumpers directly from breakout to logic board (ie no adaptor) and it worked absolutely fine
then what gives?
Is it possible that some kind of interference is going on between the breakout board and my adaptor board? It is soldered directly to it with only a 2-3 mm clearance between the two.
Thanks