lessons taught

I just call it debugging. To me, "bring-up" is more of a system integration term, whereas debug is more of a board-by-board thing.

Cheers

Phil Hobbs

(In the middle of bringing up a fancy scanning laser microscope.)

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

I once had a job that involved programming for a computer plugged into a big hunk of machinery, all new-build. There were approximately one zillion I/O lines from the machinery back to the computer. When I started, I thought that the wiring had already been checked out, but then I ran into a couple of situations where I could *not* make the output from the computer show up at the right place on the machine, or I could *not* make the inputs from the machine show up at the computer.

The official way to fix this was to write up a work request for a technician to check the wiring, so I did that, and got the requests back with "Checks to print". After I got a couple of these, I went over the code some more, convinced myself it was in the hardware, and went to my boss. He laughed and asked if I knew how to drive a multimeter, and I said yes. He told me to wait until after 5 PM, make sure the techs had gone home, and then to knock myself out. I was to be careful (some of it had AC-line voltages), not cut wires or damage connectors, etc, but other than that I could do what I wanted. He said that most of the programmers and electrical engineers there ended up doing that when they were trying to bring up a new system. I followed his advice and was able to solve several problems in a hurry.

Not all the weirdness was due to techs, though. I recall looking at the schematic for one board and seeing something like this:

1/6 7407 uP output ----|>---+---|>---+---|>---+---|>---+---|>---+---|>---+ | | | | | | o o o o o o J1 J2 J3 J4 J5 J6 o o o o o o | | | | | | rest of world -----+--------+--------+--------+--------+--------+

Part of the test procedure was start with the jumper block at J3 or J4, and move it around as needed until the timing came out right.

Matt Roberds

My motto is "Measure twice, cut once, f%$k it up anyway"

--
Les Cargill

Seems like that would be annoying to debug on.

This is called "Muntzing".

--
Les Cargill

"Time to sacrifice this thing to the god of little blue smoke."

--
Les Cargill

Bring up and BSP development seem closely related to me. You are in a twisty maze of PLLs, none the same...

--
Les Cargill

This is a law of the known universe. The wiring has never been checked out, ever. Even one of the Sat V missions, when a J2 failed, they had the sensors between two engines swapped and it took an engine down that was innocent.

It would take a small amount of time to develop a checklist to check the wiring out, but nobody will ever allocate the time. Of course, then you're debugging the goshdarn checklist, but then it's done.

BTW - see "Moon Machines". It's very, very wonderful. Especially if you have kids.

Oh, and the drawings are also always wrong. Fixing the drawings is grist for the mill, so the incentives guarantee this.

It's all trimpots until we put them into software, and then it's "configuration".

--
Les Cargill

"I cut the wire three times and it's *still* too short."

Stretched copper bus wire is beautifully straight. Looks great on breadboards. Of course, the stress wrecks the conductivity.

Chuck one end in a vise, grab the other with pliers, pull until you feel it give a little.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

Well, no more than it was. It's not like it's silver, but the increment is about the same.

Alloying really messes with the conductivity, though. As I recall, brass (yellow, 70-30) is worse than not only copper, but pure zinc as well. Which is actually only a little bit worse than aluminum.

Conductivity is overblown. Steel jumper wires are more conductive than the fat copper PCB traces they bond, simply because PCB traces are so damn thin (1-2 mils), and that jumper wire might be a hulking 10-20 mils in diameter.

Unless you're working with a real pig, like manganese, or plutonium, conductivity largely isn't a problem.

Tim

--
Seven Transistor Labs, LLC 
Electrical Engineering Consultation and Contract Design 
Website: http://seventransistorlabs.com

It's not a lot, not much more than the diameter reduction explains. Connect a 4-wire ohmmeter as you stretch it.

Plutonium-FR4 boards? At least it would be ROHS compliant.

Somewhere I read (in the silly Black Magic book maybe?) about PCBs that had sandwich copper-ferrous (magnetic) traces, or maybe ferrous planes, that did something good.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

I think the difference due to work hardening is in the 0.5% range. Silver is 6%, which is more, but still nowhere near the Ten Percent Rule, let alone an orders-of-magnitude improvement.

Now, show me the electrical equivalent of a single crystal diamond substrate hybrid, and we'll be talkin'...

???

Although I suppose they don't actually name the stuff, do they? So you might be technically correct (the best kind of correct). I'm sure it falls under a hundred other, more obscure, laws though.

I can't say I've used Pu in circuit, but I know a guy whose business it is to use intense alternating magnetic fields nearby. You probably know plenty of people who do similarly obscure or violent things to odd parts of the Periodic Table.

There are metal core PCBs of various sorts (with or without FR-4 layers), to improve conductivity or strength or thermal expansion. Molybdenum being one of the more unusual (but kind of not) metals involved.

I'd love to know more about Mo, metallurgically speaking. I know it's been used for electrodes in vacuum tubes and physics apparatus, heating elements (also MoSi2), and a variety of other things. I think it has some alloys that resemble either iron or titanium in behavior (i.e., precipitation hardening or martensitic-like heat treatments). I suppose the biggest problem is, it's heavy, expensive, and not especially stronger than conventional alloys, so it's simply not used much.

Also think I've heard of ferrite loaded PCB material. Or maybe I was just fantasizing. It would be lovely to do power conversion circuits in the MHz with a dual core PCB: one loaded with hi-K dielectric, another with hi-mu core. Loop traces around and stitch between for inductance, planes around the other for capacitance.

Technically, your schematic would show a switching regulator connected directly between input and output, like a 7805 with an output reverse-protection diode, no other components needed.

Can also do low frequency planar filters, periodic or (potentially) distributed delay lines, shock lines, etc.

Tim

--
Seven Transistor Labs 
Electrical Engineering Consultation 
Website: http://seventransistorlabs.com

That's how new-built glass beads are removed. The stretched wire has smaller diameter, and they slide right off; you can generally build a dozen generations of beads before the wire needs replacing.

This must say something about Poisson's ratio for copper, but I'm not sure what.

I know people who do really cruel things to tin.

I don't have the silly Black Magic book here. Maybe someone who does can look for the magnetic PCB thing. It had to do with HF losses, I think.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

I tried to measure the change in conductivity in stretched copper wire due to stress.. (versus the Area/ length change) I think 20 AWG, length changes of 10 to ~25%... (the wire relaxes after you stretch it.)

No measurable change to stress... maybe you'd have to stretch it and cool it? (residue resistance or some such word.)

George H.

The handbooks show somewhat different conductivity between hard-drawn and annealed copper, but it is small. The diameter change will dominate.

Transiently, the stretching will heat the copper, too.

You can buy tinned copper wire on ebay, for jewelry or arts-and-crafts or something, cheap. It's hard and springy and doesn't solder too well, and it's not very good for breadboarding. Electronic grade solid tinned copper wire is expensive.

--

John Larkin         Highland Technology, Inc 
picosecond timing   laser drivers and controllers 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com

es

d and

"Don't

t

-Lasse

A bottle of Kester RA flux is a powerful persuader. ;)

Cheers

Phil Hoobbs