Microprocessor question

G

gary s

Guest
I have a question that I hope someone on here can answer, or give me
an insight:

1. Is there any way to do a quick check on a microprocessor to
determine if it's "alive"? I realize manufacturers use million-dollar
testers for functional testing, but is there a way to "generically" do
a quick check on the bench using standard test equipment?

2. Ditto for speed? How can one determine if a microprocessor will run
at its marked speed on a bench?

3. If there is a "generic" feature set that is common to most
microprocessors, and what might that be?

4. How can one check for this - as far as hardware and software
requirements?

I guess I am looking for a "generic" test setup that can do something
like a bare-bones electrical QC on different microprocessor families.

Thanks for your help.

Gary
 
If you're testing older processors such as the Z-80 and the 6502, you could
buy some cheap PCs such as the TRS-80 (Z-80), an Apple II (6502), a Radio
Shack Color Computer (6809) and/or an original Macintosh (68000) and use the
sockets on the motherboards or install one if not already provided. Then
just use each computer as a test bench.
 
On Tue, 26 Oct 2004 19:18:31 -0500, gary s <gary_s@REMexcite.com> wrote:

Thanks for all the prompt replies I've seen so far.

I work for a reseller, and my company acts as the broker for large
batches of different types of microprocessors bought on the "gray"
market to meet production shortages. There is no longer any
manufacturer's warranty, therefore there is a desire to screen out
parts that are dead, slow, or counterfeit. It appears there are folks
out there who are making a living remarking slow parts, or assembling
parts that have been scrapped off the manufacturer's production
line...

I've been told that after a microprocessor leaves the manufacturer,
there is really no way to test it except on a motherboard/application
board (or some kind of evaluation board). My customers are doing this
after their assembly process. But it would be nice to have some kind
of meaningful acceptance testing at my end before they get the part.
(snip)

Because of the diversity of types/pinouts I suspect you are chasing the
unachievable unless you have a '70s NASA budget.

What you COULD do is consider moving the client testing into YOUR facility. If
they can provide either end-product or a test jig for the specific micro they
purchase, your outfit could do the testing before on-shipping the chip. That
would relieve them of that burden and give your firm not only confidence in the
shipped part but also a reputation for actually giving a stuff about the client.
 
"gary s" <gary_s@REMexcite.com> wrote in message
news:qfetn0tohn45q767g4okh70obnol7g9a1f@4ax.com...
I have a question that I hope someone on here can answer, or give me
an insight:

1. Is there any way to do a quick check on a microprocessor to
determine if it's "alive"?
Most single chip micros will configure all the pins as inputs on Reset/POR.
Early in the code the programmer has to configure the pins to be inputs or
outputs. If you see all the pins floating or pulled hi/low by external
components then it probably hasn't executed that early code. If we are
talking about a new flash programmable part then it's also possible someone
forgot to program it (eg it's still blank!).
 
"gary s" <gary_s@REMexcite.com> wrote in message
news:k7qtn0lclsqhurcvlm0pnsa10jp5ov38hq@4ax.com...

My customers are doing this after their assembly process.
Please let us know who your customers are so we can avoid buying from them!
 
On Tue, 26 Oct 2004 20:13:23 -0700, Tom Seim wrote:

gary s <gary_s@REMexcite.com> wrote in message news:<qfetn0tohn45q767g4okh70obnol7g9a1f@4ax.com>...

Thanks for your help.

Gary

Do you have a known "good" board?

If so, you can probe around with an oscope and you will get some
repeatible waveforms. Now go to your "bad" board and do an A-B
comparison. With some trial and error you will find some waveforms
(pins) that will give you a "state-of-health". And this without
knowing anything about the processor or application.
I believe you've just invented the "signature analyzer." :)

Cheers!
Rich
 
On Wed, 27 Oct 2004 19:24:05 GMT, "CWatters"
<colin.watters@pandoraBOX.be> wrote:

"gary s" <gary_s@REMexcite.com> wrote in message
news:k7qtn0lclsqhurcvlm0pnsa10jp5ov38hq@4ax.com...

My customers are doing this after their assembly process.

Please let us know who your customers are so we can avoid buying from them!
Chances are you have something in your house from one of my customers.
But rest assured their outgoing QC is 100%.

A lot of my inventory comes from OEMs in sealed, virgin condition so
there is little that needs to be done. There is a huge market for
excess and obsolete parts, and there is always a demand somewhere for
them. Unfortunately, it is the stuff of questionable pedigree that's
giving everybody headaches.

Regards -

Gary
 
On Wed, 27 Oct 2004 09:59:56 +0000 (UTC), "Gareth Magennis"
<sound.service@btconnect.com> wrote:

It is not beyond feasible to build a test jig for each microprocessor
family.

For example, I've been messing about learning the 8051 processor family. I
have an EPROM / Flash programmer I bought new from ebay for about $45 which
will program almost everything. My "Test Jig" consists of a prototyping
breadboard into which I've plugged a simple power supply, the processor
(with onboard flash memory), one crystal and 2 capacitors (for the clock)
and a reset switch. You can write a trivial looping program to output a
square wave, program the processor using your PC, use the maximum crystal
frequency, and see if you get a square wave. For processors without onboard
program space you can add an EPROM to the breadboard and blow that instead.
This jig should work for all processors in the 8051 family of the same
package (number of pins). This will indicate the processor can run a basic
function at maximum rated speed. There could be other faults of course
(falty onboard RAM) but it sounds like this simple test is what you need.

If all this sounds too daunting, get a Microprocessor Programming book and
spend a few evenings reading it, and you may find it's well within your own
capability. This isn't rocket science despite appearances.
This is similar to what was suggested to me. My problem is in somehow
"generalizing" this to a superset to include 16 and 32-bit parts with
hundreds of pins.

Thanks -

Gary
 
Yes, sorry about that, I was assuming the poster was talking
microcontrollers in consumer equipment rather than big computing systems. I
see a lot of this stuff.



You're right about a microcontroller like the 8051. But the common
microprocessor has more than ten times the number of pins, and it's a
lot more than rocket science to get it running without any support
system.
 
On Wed, 27 Oct 2004 09:52:49 +0800, budgie wrote:

On Tue, 26 Oct 2004 19:18:31 -0500, gary s <gary_s@REMexcite.com> wrote:
[about uP testing]
Because of the diversity of types/pinouts I suspect you are chasing the
unachievable unless you have a '70s NASA budget.

What you COULD do is consider moving the client testing into YOUR facility. If
they can provide either end-product or a test jig for the specific micro they
purchase, your outfit could do the testing before on-shipping the chip. That
would relieve them of that burden and give your firm not only confidence in the
shipped part but also a reputation for actually giving a stuff about the client.
Hear! Hear! This is actually a very good idea.
Guess I'm getting old in my old age. ;-)

Have Fun!
Rich
 
Good reason to stay away from "independent" distributors - No
warranty, suspicious circumstances re how they get their product.
Stick with the "franchised" distributors. They get their parts
directly from manufacturers. They also receive full technical support
from manufacturers (as opposed to having to ask questions on Usenet)
 

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