Setup Question

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technoplastique
Posts: 4
Joined: Thu Apr 16, 2009 5:03 pm

Setup Question

Post by technoplastique » Thu Apr 16, 2009 10:26 pm

As far as I can tell I have everything set up as the directions say, but I can't get anything to happen on the LED matrix. The BBB works like a dream by itself, but, like I said, the matrix hasn't lit up once (since I did the LED check during assembly.) I'm attaching a couple pics, let me know if anything looks amiss (the solder points are all cleaned up and silver, they just look kind of grungy in the artificial light I'm using for pics. I'm out of ideas on things to check or change.

Thanks!
Kris
DSC07434.jpg
Just the matrix
(345.19 KiB) Downloaded 4199 times
DSC07438.jpg
All plugged in
(373.13 KiB) Downloaded 4198 times

paul
Site Admin
Posts: 706
Joined: Mon May 12, 2008 4:19 pm

Re: Setup Question

Post by paul » Thu Apr 16, 2009 10:43 pm

technoplastique o,

One thing I see is that you should swap the shunt on the PRJ pins to the "ext" position. (and make sure you have either a 5V or 6V regulated supply). With the shunt in its' current position all the power is running through the 250 mA regulator, which is pretty wimpy for the sign panel. Also swap the shunt on the USB/EXT to external position.

Check the power lines on the LED board to make sure you have power there.

Also check the pin assignments on the BBB / 8x8 labels to make sure they agree with the ones in the demo sketch.

Maybe download the datasheet for the driver chips and print out a pinout for the chip. Then you can put your meter on "beep" and make sure you have really have continuity between the BBB pins and their intended pin destination on the chips.

Reheat any solder joints that look suspicious. I'm sure it's something small - it's just there are a lot of things to check ...

Write back if you don't get it going with those suggestions.

Paul

technoplastique
Posts: 4
Joined: Thu Apr 16, 2009 5:03 pm

Re: Setup Question

Post by technoplastique » Fri Apr 17, 2009 1:31 am

For the PRJ - should the three pin header that came with the board be on the +5 and the exts, or on the exts and the +V? The instructions on the site are from a previous version of the BBB and didn't really specify how to handle that for this board.

My power supply is a 5v regulated supply (that I found through a link you posted on the forums here.)

I had the shunt on the ext (not usb), I had just forgotten to change it back for the picture (I retested the blink to try to narrow down the problem.) I've tested power all over the place on the two boards and I can't find a breakdown anywhere doing that.

This BBB plugs into that header from pin 4 to pin 8, I changed the numbers accordingly in the sketch (both the Asimov you posted and the random flash posted in the forums.) Was that the right way to handle it? (Changing pin 2 to pin 4, etc.)

I'm much better at soldering than sketches so I've been over that a few times and I'm pretty confident in that.

Downloading the datasheet is a bit more advanced than what I've done in the past so I thought I'd check on these things before I tried figuring that out.

Thanks!

paul
Site Admin
Posts: 706
Joined: Mon May 12, 2008 4:19 pm

Re: Setup Question

Post by paul » Fri Apr 17, 2009 5:47 am

Here's a link to the A6279 datasheet

http://www.allegromicro.com/en/Products ... 8/6278.pdf

You can make a low-end serial troubleshooting tool with a speaker and an 50 - 1000 ufd electrolytic capacitor in series. You can hear the pins toggling

Paul

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