Dead Prop

Rayman

Finally managed to kill one of my Props [noparse]:([/noparse]
Knew it had to happen one of these days...

I was having some power supply issues when it died (dragged down the supply with too much load)...· But, I'm not really sure why that would have killed the proto board...

I'm only upset because of all this stuff I had on it, that I need to move to a new board...

As far as troubleshooting, I don't think there's much you can do if it won't "identify" from the Prop Tool, right?

It's got good 3.3 Vdd...

Rayman

Good news is the proto board price has dropped to $19.95. Bad news is the 5-pack is $100...

Paul Baker

I hear you on the frustration of having to transfer your circuit. I noticed you are using a metallic enclosure, is it possible part of the board or a stray wire shorted through your case to cause the failure?

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

Nick Mueller

> Finally managed to kill one of my Props [noparse]:([/noparse]

Condolences!

> I'm only upset because of all this stuff I had on it, that I need to move to a new board...

Repair it? I mean if you know that it is the Prop, I'd unsolder it and put a new one in.

If you have a scope, trace the signals in and out to P30, P31 when connected to the PropTool. On power up (w/o PropTool) you should see a signal on P28/P29. Check wether BOEN is sett right.

But if a new board costs only $19.95, it's not worth fireing up the solder iron.



Nick

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Never use force, just go for a bigger hammer!

The DIY Digital-Readout for mills, lathes etc.:
YADRO

Beau Schwabe

Check your regulators... If you had a power supply "event", perhaps one or more of your regulators are not exactly happy at the moment.
·

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Erik Friesen

I have had a propeller die a slow death and pull surrounding components down with it.· If the inputs are damaged in some way the prop can pull an excessive amount of current doing something and get quite hot, almost like something is shorting inside the chip itself.

Rayman

I imagine that I shorted something out somewhere to cause the problem, but I don't know where...
The power supplies are fine now. I think there was always 3.3 V...

I put a scope on the pins and P30 gives a sad little 1.5 V spike with ~2ms decay when power is applied. This is the only sign of life...

Had my Parallax shopping cart full of stuff when my computer died [noparse]:([/noparse]... I'm really having a bad day now.

Erik Friesen

You can get hot air guns for around $120. Or if you are desperate you can use a torch to get the old one off. Shield everthing else with tinfoil. Its not that difficult to replace the chip once you get it off. Just don't tear of the pcb leads.

Nick Mueller

> I put a scope on the pins and P30 gives a sad little 1.5 V spike with ~2ms decay when power is applied.
> This is the only sign of life...

Did you check that reset is high?

If not OK, maybe the problem is somewhere else, the serial I/O.
In such cases, I'd cut the line on the PCB (just a little gap with a **sharp** knive) going from P30 to the peripheral. If the signal is OK then, search on the serial's side.

Nick

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Never use force, just go for a bigger hammer!

The DIY Digital-Readout for mills, lathes etc.:
YADRO

Rayman

I did just order a replacement chip for the proto board (along with a bunch of other stuff).· I'll see if replacement brain surgery can fix it...

Reset\ is high...

I just wish Digikey carried the proto boards, then I could have made just one order...

Rayman

I did find that one of the prop pins I wasn't using happened to be connected to ground... Perhaps, during the brown out (when my power supply was failing because I put too much load on it) the prop somehow tried to output high there... I imagine that would kill the prop. But, there was no code in eeprom or ram that should have used that pin...

Leon

An easy way to remove chips without damaging anything is to use Chip-Quik:

http://www.chipquik.com/

Leon

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Amateur radio callsign: G1HSM
Suzuki SV1000S motorcycle

Drone

Condolences Rayman. I wake up at night in cold sweats fearing the same thing will happen to me (just kidding). I use a little homebrew 40 pin DIP board with a header that goes over to a plugboard. That way I can use the same prop for different projects. Of course the 40 pin prop is socketed - just in case.

I too was wondering why five proto-boards cost $99.75 but the 5-pack costs $100. Emailed Parallax moments ago the burning question. Methinks Prop Proto-Boards make nice sock-stuffers.

Regards,

David

Rayman

I'm starting to think that a DIP based board has the advantage that the chip can be easily replaced. We fry a lot of electronics in my line of work, so when I design my own board, I think it will be with the DIP chip. Or, maybe I should look into the PropStamp or variants... On the other hand, the proto board is so cheap, it's hard to argue against it. Maybe I'll just use a bunch of headers on the proto board to attach my stuff, so that it can be more easily moved to a new board...

Rayman

I wonder if I could just solder the new chip on top of the old one...

Drone

Got a prompt reply from Dave A. at Parallax about the 5-pack proto-board pricing:

"Thank you, I will have this corrected. If you put in quantity 5 in the
cart it will come out to a subtotal of $99.75. If you have any more
questions please feel free to e-mail us."

I replied (in other words) to David A. at Parallax that I would like to see the 5-pack priced a bit lower than just 5X1-proto-boards at check-out. Let's see how it goes; hopefully a price break on the 5-pack in-time for Christmas! If not, the proto-board at the current price is still a pretty good deal.

Regards, David

darco

I imagine that you guys at Parallax have seen and dissected a lot of dead props over the past two years or so. I was just curious as to what the most common failure modes were. I've made some pretty serious mistakes with my props, but I have yet to fry one yet. They seem quite robust. I figure if I was aware of the most common ways that propellers fail, then perhaps I could avoid such failures. But really, I'm just curious. [noparse]:)[/noparse]

Also, are there any partial-failure states that you've seen that were common? What sort of symptoms would occur?

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—
darco
www.deepdarc.com/

Rayman

Put in a new chip and... All better!

I used a razor around the edges (I think somebody mentioned this technique) and then pried it off...·
Unfortunately, I lost one pad doing this...· It was one of the crystal pins, so I had to run a jumper wire over.

I put in a crystal with long leads because I'm not completely sure if the crystal case is floating or not...

Rayman

I think I may know what happened... My homemade SD card connector was fine until bent... Then it shorted all the pins together [noparse]:([/noparse]

I think this may have shorted Vdd to Vss, where Vdd came from one of the through-holes around the Prop. I'm thinking that this drew a bunch of current THROUGH the Prop, instead of around the Prop. But, that's just a guess...

I think a real power plane would help...

Drone

I got a reply from Dave A. at Parallax about the price of the 5-pack proto-board. It seems the 5-pack will end up $99.75 at check-out and that's the price it will stay at. He says the proto-board is being sold at no profit as an introduction to the Propeller. Looking at the BOM, even in reasonable volumes I tend to agree with him.

Regards,

David

slosjo

If you need to replace a fried prop chip, an easy way to get the old one off is to heat each pin with a fine tipped soldering iron and bend it up and out of the way with a small pick. This way, you can get it off and save your protoboard without damaging any of the pads. Putting a new one on is just as easy; start with the corners and do one pin at a time.