Weird problem with Charlieplex shield

[SukkoPera]

Hi,

I have just finished building my Digispark stuff (http://t.co/THsyhQuwk5). Everything seems to work correctly, except the Charlieplex Shield, which exhibits a weird problem: if I plug the Digispark in with the shield mounted, it seems to never switch to program execution mode. It just sits there with all the leds turned off, except the bottom one of the 4th row which flickers dimly.

Instead, if I plug the Digispark in *without* the shield, wait >5 seconds and then mount the shield on the Digispak, the program executes correctly and lights one led at a time (of course I'm talking about the Charlieplex demo). I should add that while the leds are being lit, from time to time some of the leds which should be powered off flicker dimly.

Has anyone else experienced this? What can it be? I must admit I might have damaged the resistors while I was soldering the headers (I'm pretty lame at soldering...), but it sounds pretty weird...

Thanks in advance!

[SukkoPera]

No replies?


I've soldered headers to another Digispark, just to make sure the issue was not due to that particular board, but the problem persists. I've made a (bad) video of what happens, you can see it here: http://youtu.be/WsCzMzfm4Rc


First you'll see how the demo won't start when the digispark is plugged in with the shield. Then I'll plug it in later and you'll see it works, more or less.


Is my Charlieplex shield damaged or what?

[Bluebie]

It sounds like your shield is damaged and is affecting the digisparks' power supply harshly. I am of course counting on the fact that you have certainly not installed any alternative 3rd party bootloaders on your digisparks.


I'd recommend going over the PCB very carefully checking for shorts with a multimeter and looking for areas where it maybe bridged. If you cannot find any, I'd be suspicious of the resistors. The inconsistency in brightness of some LEDs make me think there is some funny business going on with the resistors, but that could just be some of the LEDs being a bit burnt out from being left hot with a soldering iron for too long or from short circuits caused by dodgy resistors or solder bridges

[ElectronicWar]

I have the same problem with this, but I think the programming part is due to using at least 5 pins to drive the
charlieplex matrix (5 pins can drive 20 LEDs) and so not being able to "switching" to USB mode.


Anyway, I have a problem with not being able to properly light up every LED separately.
Not sure what I have damaged during soldering :/


http://www.youtube.com/watch?v=s_XqbpAPORk
The left row always lights up together with the one next to it, same problem with the last column.

[Mark]

I'd be checking you have all the LED's around the right way.

I'd suggest a checking script where only One Pin is high, with the others low, is a good way to ensure the columns work.
It will show up any LED issues.

The 47ohm and the LED is very likely to interfere with USB, so try with the shield removed.
 

Mark