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61  Using Arduino / Installation & Troubleshooting / Re: Uno Board on: December 27, 2012, 08:12:18 pm
Are you powering it from USB or from the power jack.  If the power jack, what are you using?

If you are powering from the USB port, make sure you're plugged directly into the computer and not into a hub, keyboard or monitor port.

Many of those ports only supply 100ma which should barely be enough. I've tested my Uno at 85mA peak so far, but just running LEDs and a speaker.  If you have more inputs and outputs running, you could be too low. I've found some keyboards that can't give enough juice to power some thumb drives.

I tried running my Uno off of 3 AA batteries that were in a rechargable battery pack directly to the jack but the lights just dimly flickered and the sketch didn't run.  Not enough juice.

62  Using Arduino / Installation & Troubleshooting / Re: Duemilanove chip in an Uno on: December 27, 2012, 05:00:51 pm
They were going for a dollar each which was the cheapest I could find a 328p-pu on amazon.  I have a 30$ gift card I got for Christmas for Amazon so I was planning on buying some Arduino stuff.  Right now I just have the newsite uno r3 kit with the breadboard and wires but no components.  I was considering the green box kit that's on amazon for $22.50 but it already has the breadboard and wires which I already have.

63  Using Arduino / Installation & Troubleshooting / Re: Duemilanove chip in an Uno on: December 27, 2012, 04:57:05 pm
Ok looks like I may have found the right search query to find a similar topic:

http://arduino.cc/forum/index.php/topic,139160.0.html

Looks like the answer is, yes, but you must select Duemilanove when you use a chip programmed originally for the Duemilanove.

Maybe if I pick them up, I'll put a D on them with a marker so I remember to upload programs in Duemilanove mode.

EDIT: This was posted before I saw the response above.
64  Using Arduino / Installation & Troubleshooting / Duemilanove chip in an Uno on: December 27, 2012, 04:51:35 pm
I found a guy on Amazon selling replacement pre-programmed "Duemilanove only" chips pretty cheap. The part number seems to be the same as the one in my Uno. Would that chip work unmodified in the Uno, or would it have to be reprogrammed in order to work?

If they'll work "out of the box" I might pick up a few so I could migrate projects off the board easily.
65  Using Arduino / Project Guidance / Re: Building a tester for a special cable. on: December 18, 2012, 12:40:00 am
I don't have an official pinout of the cable but from continutity testing, no pins are cross connected. It does appear to be a 1 to 1 connection.

The side of the cable that goes to the device being tested has a known pinout. Theres, power (12 to 24v), ground, Bus 1 data+, Bus 1 data-, Bus 1 common, Bus 2 data+, Bus 2 data-

The final pin has no listed function, but it does correspond with a pin on the other side of the cable.
Not having the electronics background, I would suspect if the cable normally gets 12-24v, you would want to test it with 12-24v, otherwise you might miss problems that don't show up with smaller voltages, but does show when you are using the cable as expected.  Obviously with the Arduino, you can't drive it at that voltage directly, and would need an opto-isolator, relay, or similar to drive the voltage.

Yeah but it's low current. The diagnostic tool can also be powered from a USB port. So shouldn't be more than 2.5W drawn on the cable.

The cable itself when cut apart looks like ethernet with a woven sheath over it and then dipped in the same stuff the black coating on a computer power cord appears to be.

I think for intermittent cable breaks I've got a good idea now about what I'd like to try.

66  Using Arduino / Project Guidance / Re: Building a tester for a special cable. on: December 17, 2012, 06:56:23 pm
I don't have an official pinout of the cable but from continutity testing, no pins are cross connected. It does appear to be a 1 to 1 connection.

The side of the cable that goes to the device being tested has a known pinout. Theres, power (12 to 24v), ground, Bus 1 data+, Bus 1 data-, Bus 1 common, Bus 2 data+, Bus 2 data-

The final pin has no listed function, but it does correspond with a pin on the other side of the cable.
67  Using Arduino / Project Guidance / Re: Building a tester for a special cable. on: December 17, 2012, 06:36:25 pm
This is a very interesting idea as well. The protocol used on the cable I believe is capable of 500kbps so at 1 to 3 feet, I think should be capable of the fastest speed the arduino can send to it.

If this is a simple pin-to-pin cable, you can do a "walking ones test".    One end of the cable is connected to 8-outputs, and the other end connects to 8-inputs.    As long as you read-back what you write, the cable is OK.     

You write a pattern that looks like this in binary:
0000 0001
0000 0010
0000 0100
0000 1000
0001 0000...

With 8 reads & writes, you can check all 8 connections for opens or shorts.  (You'll want to add some resistors to the ouputs to prevent shorts from damaging the Arduino.)

To catch intermittant failures, you can run a loop and latch or count the errors.

Then, all you really need is one LED to indicate "good".   If you want to diagnose exactly what's wrong, you can add a header or some kind of break-out pins to hook-up a multimeter.

Or if you're not worried about shorts, just hook-up 8 LEDs with no "brain chip".  If one LED doesn't light-up, or if it flickers when the cable is flexed, you've got a failure.
68  Using Arduino / Project Guidance / Re: Building a tester for a special cable. on: December 17, 2012, 05:54:02 pm
(This is in reply to Michael, I hadn't read the other post yet)

Ok, some slight changes based upon your information.

How about (if this is possible) running the LED inline with the cable and then cutting the power to the LED if an interruption is detected in mode 2.

So basically bring 8 pins high to complete the circuit and light all the LEDS and if by shaking the cable a circuit is interrupted, take that pin low until the device is reset and continue scanning the other pins.

Would I be able to detect a circuit interruption? Or can the pins only be input or output?

The cable itself will be anywhere from 1 foot to 1 meter. 300V rated 24AWG shielded twisted pair marked 2464. The shield is braided on the inside and is plastic or vinyl coated on the outside.

The cable will not be powered by anything other than the tester. In practice the cable runs from 12 to 24v in its normal environment.

The tester will have connectors corresponding to both sides of the cable, and the cable will simply complete the circuit.
69  Using Arduino / Project Guidance / Building a tester for a special cable. on: December 17, 2012, 04:47:58 pm
I would like to check the feasability of this project.
We have an 8 pin cable we use at work for a piece of machinery that is expensive to replace, but unfortunately it has to be carried around quite a bit in an industrial environment as it is connected to a diagnostic device. The problem is finding the intermittent cables that work maybe 95% of the time but fail 5% of the time. We think this is because an intermittent connection inside the cable or in the soldering or crimping at the plug at the end. Unfortunately the plugs are factory sealed and can't be inspected without cutting them open which ruins them.

I have the concept of my tester.

Have 8 Red/Green LEDS
1 switch to toggle testing modes

We'll plug both ends of the cable into the tester and in testing mode 1 all the lights will stay green but will flicker back to red if there's an interruption.  (The plan is connect the cable and shake it around vigourously)

Testing mode 2 would be when it detects a momentary interruption in the cable, it holds the light red indefinitely and keeps polling the other lines until the unit is reset.

I could see the possibility of toggling the red/green being a problem without adding additional hardware, if that's not easily doable I'd consider just blanking out the LED.

I'm new to Arduino but have watched many tutorial videos, the code looks simple to write up. Do you think that it will have enough pins with an UNO? If the prototype is good and we decide to make another one. That time I'd think I'd go ahread and forgo the board and run the chip directly which also looks simple enough.

Any caveats or dragons ahead?
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