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Ductapemaster
05-01-2007, 08:16 AM
I have a BS2SX integrated into a project of mine and it seems that one of the outputs is not working. I tried writing a program that turns the output and loops to keep it on, but no voltage shows on the pin (pin 14) no matter what I do. I have had no other problems with this stamp other than this one. Does anybody recommend a test or something to that degree that I could use to determine whether or not the pin really is bad? Also, I can't just switch to another output, as all 16 I/O's are used.

Thanks in advance,

Dan

Duffer
05-01-2007, 09:25 AM
You said all 16 I/O's are used. looking at the specs for the sx:
http://www.parallax.com/dl/docs/prod/stamps/stampscomparison.pdf

Each I/O pin will only source/sink a maximum of 30 mA and a total of 60 mA per 8 I/O pins. I don't know what you have connected to all those pins or exactly what the consequences of exceeding those limits would be, but I would bet that it's not good.

A simple "flash the LED" program and circuit should be sufficient to test the pin. If you can flash the LED on pins 13 and 15, but not on 14, I'd say 14 was dead.

Steve

Ductapemaster
05-01-2007, 11:09 AM
None of the pins sink anything close to 30mA...7 pins drive a ULN2003 for a seven segment display, 4 more drive another 2003 for bicolor LED's, one drives a relay, 2 are inputs from buttons and one drives a small buzzer. I was careful not to pull too much current from the pins, hence the 2003's. The pin that went bad is connected to the 2003 driving the LED's. I didn't use it before (I only had regular LED's and this was an auxiliary output for the other color of LED) so I had no idea as to whether it worked or not.

And yes, all the other pins work in my project except that one (and my soldering is fine).

I might implement a two transistor design so that when pin 15 is high the LED is one color and when it's low the LED turns another color.

One more thing, this stamp was free...I won it from Parallax a couple years ago, so I'm not too bummed.

Thanks

-Dan

Chris Savage
05-01-2007, 11:49 AM
Dan,

Are you saying you’re driving a Relay directly off the pin? What was the pin that failed driving?

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Chris Savage
Parallax Tech Support

Ductapemaster
05-01-2007, 12:49 PM
Sorry, I meant to say that the relay was driven by an NPN transistor. The pin that failed was driving one of the ULN2003's. As far as I can see, it was damaged sometime in testing, or it never worked at all. I recently installed the bicolor LED's so I never really had a chance to test that pin. The regular LED's were driven by pins 13 and 15, and now I added pin 12 and 14 to control the other color.

Chris Savage
05-01-2007, 10:11 PM
Well, it’s hard to tell from your description of connections, but there is a limitation on total current per group of 8 I/O pins. On a BS2sx you cannot source/sink more than 60mA per group of 8 I/O pins. That is besides the normal per pin limitation of 30mA.

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Chris Savage
Parallax Tech Support

Ductapemaster
05-02-2007, 06:28 AM
I'm in the process of drawing a schematic for the project, so I will post it when I'm finished.

As far as I can tell, the pins all sink very little current, but I will post it just to be sure.

Thanks,

Dan

Chris Savage
05-02-2007, 06:39 AM
Dan, one last thing to keep in mind...Duct Tape is conductive. =)

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Chris Savage
Parallax Tech Support

Ductapemaster
05-02-2007, 06:43 AM
Really? You can't be serous...if it's true, I guess I'm not the true master of duct tape.

-Dan

Ductapemaster
05-07-2007, 05:59 AM
I don't understand it. The problem is seemingly getting worse. First, pin 14 went bad, now pin 13 is either on or in Hi-Z state. There is no 'off' state. Also, the stamp keeps resetting. I'll turn on the power, and about 10 second later, the stamp resets itself every 10-15 seconds thereafter.

Any ideas? I have the proper voltage going to the stamp from an external regulator and the drain on each pin is nowhere near the max...

Is there any way to get a replacement? I know the stamp was free was free to start with (I won it from you guys...), but shouldn't it still work?

Thanks in advance,

Dan