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--- In Electronics_101@..., "Len Shelton" <len@...> wrote:

Then, in Myke's apps it makes perfect sense. In fact, that should nearly
eliminate interrupt latency.

Thanks. That's the piece that brings it full-circle for me.

Len

So, the interrupt flags get set, even if interrupts are not enabled?

Yes, just like any other flags.

While you are at it, look around at some of the code on the Microchip
site. Some of it is quite good and uses more modern coding standards.

I don't have any of Myke Predko's books but some of the code by other
authors purporting to teach all about microcontrollers has the
absolute worst coding style on the planet.

If you see memory allocation like:

Var1 EQU 0x20
Var2 EQU 0x21
Var3 EQU 0x70

run away as fast as you can. Similarly, if you see EQUs used to
define registers and flags, run even faster.

In the first case, the CBLOCK - ENDC was invented to create and define
the contents of blocks of memory. Specific addresses within the
blocks are handled by the assembler.

In the second case, the code is probably not portable. The Microchip
assembler include files contain the only correct definitions for the
various registers and bits.

Just a little heads up...

Richard

--- In Electronics_101@..., "Leon Heller"
<leon.heller@...> wrote:

----- Original Message -----
From: "lcdpublishing" <lcdpublishing@...>
To: <Electronics_101@...>
Sent: Friday, October 06, 2006 11:48 PM
Subject: [Electronics_101] How limitting do you think a scope would

be if it

were limitted to 35 volts?

How limitting do you think a scope would be if it were limitted to
35 volts?

There is a PC based scope - USB interfaced, that I have been
eyeballing. It isn't cheap, around $300.00, but it is dual channel
and rated up to 60 Mhz which should be fine for me.

The real kicker that I am liking about the PC scopes is recording.
For some reason, I think that is important, not sure why, but I do ;-
)

The drawback is that voltage limit though. While most everything I
check is 5~12 volts, I have checked the output of my Stepper Driver
and that is at 41 volts.

This is the one that is being considered

A second-hand analogue scope would be about the same price and would

be a

lot more useful.

Leon
--
Leon Heller, G1HSM
Suzuki SV1000S motorcycle
leon.heller@...

Exactly right! I bought a used Tektronix 485 via eBay for less money
than that and it has 350 MHz of bandwidth. No storage, no recording,
just a plain, ordinary, analog scope. But it's what I have always wanted.

Richard

On Sat, 07 Oct 2006 05:48:05 +0200, James M.(Jim) Geidl <jgeidl@...> wrote:

That scope is a 1972 model if anyone is interested.
Jim

And it will outlast the velleman thing by a few decades ;-)
You'd have to ask if there are any plugins with it, since the 7704 is a plugin scope.


Anyway, i think Chris really wants a storage scope (and i would recommend it for his type of work), so the 7704 is out (at least without 7D20 plugin). Since he already had bad luck with one used scope, i reckon he doesn't want to take that risk again.

As others said standard probes will fit the velleman thing, 10:1, 100:1, even 1000:1, to increse the input range. This seems a fairly decent one for PC scope standards, with 1Gsample.
You'd have to set it up properly with a PC or laptop so it is somewhat comfortable to use.

ST

"Greetings, all: I have a really nice 7704 that isn't getting used. I hope
someone on the list can use it. Excellent cosmetic and electrical
condition. 200 mHz bandwidth. Asking $280 shipped and insured CONUS (it's
pretty heavy!). I can send you a photo if you're interested. Please reply
off list. Thanks for the bandwidth....Mike W2IY"
I don't know anything about that specific model, but I'm sure he wouldn't
mind answering a few questions about it, at "albert prazolam"
<devnull8it@...>

Then, in Myke's apps it makes perfect sense. In fact, that should nearly
eliminate interrupt latency.

Thanks. That's the piece that brings it full-circle for me.

It is sad that some people have so much time to waste^H^H^H^H^Hspare <g>.

Steve Greenfield wrote:

That scope is a 1972 model if anyone is interested.

Jim



"Greetings, all: I have a really nice 7704 that isn't getting used. ?I hope
someone on the list can use it. ?Excellent cosmetic and electrical
condition. ?200 mHz bandwidth. ?Asking $280 shipped and insured CONUS (it's
pretty heavy!). ?I can send you a photo if you're interested. ?Please reply
off list. ?Thanks for the bandwidth....Mike W2IY"

I don't know anything about that specific model, but I'm sure he wouldn't
mind answering a few questions about it, at "albert prazolam"
<devnull8it@...>

OK, I'm a smart aleck at heart. So someone sent one of those "did
you get this message" tests on another list, and this was my
answer:

I'm writing back to formally inform you that I did not receive this
missive. That the electrons bumped by your pressing of the keys did
not, in fact, travel more than a short distance before bumping into
other electrons. And even those electrons just bumped into other
electrons, and so on until an echo of those bumped electrons
arrived on my computer like waves on a distant shore, carrying an
echo, a many-times copy of your original key presses.

That it would have taken the electrons, traveling at a drift
velocity of approximately 2.4 x 10^-9 meters/sec, approximately 18
Billion years to travel here, and I fear you won't have the
patience to hold down the keys that long nor will Earth persist for
that much longer before being engulfed in the Sun when it goes into
it's red giant stage.

So I must inform you that your message will never, in fact, arrive
here.

Sadly, all this is for naught, as my message will similarly never
arrive at your destination and instead you must be satisfied with
this many times copied echo of bumping electrons.

And by the way, the power company is cheating you. They've never
delivered, nor will they ever deliver, the electrons they are
charging you for monthly. They only send them approximately 2mm at
most down the wires to you before yanking them back, then like a
big tease, 2mm down the wires again.

Steve Greenfield

So, the interrupt flags get set, even if interrupts are not enabled?

On Friday 06 October 2006 11:12 pm, you wrote:

On Friday 06 October 2006 10:48 pm, Leon Heller wrote:

A second-hand analogue scope would be about the same price and would be a
lot more useful.

You're probably right about this -- I keep hearing that used Tek scopes are
showing up on ebay and similar places fairly regularly, and that would be
a better deal as far as I'm concerned.

This just showed up in the yahoo "Tekscopes" list:

"Greetings, all: I have a really nice 7704 that isn't getting used. ???I hope
someone on the list can use it. ???Excellent cosmetic and electrical
condition. ???200 mHz bandwidth. ???Asking $280 shipped and insured CONUS (it's
pretty heavy!). ???I can send you a photo if you're interested. ???Please reply
off list. ???Thanks for the bandwidth....Mike W2IY"

I don't know anything about that specific model, but I'm sure he wouldn't
mind answering a few questions about it, at
"albert prazolam" <devnull8it@...>

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Friday 06 October 2006 10:48 pm, Leon Heller wrote:

A second-hand analogue scope would be about the same price and would be a
lot more useful.

You're probably right about this -- I keep hearing that used Tek scopes are
showing up on ebay and similar places fairly regularly, and that would be a
better deal as far as I'm concerned.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Friday 06 October 2006 10:48 pm, LT Ron Wright wrote:

Chris,

You can get 10:1 probes. All I've seen have a switch for selecting
times 1 or times 10. Are there probles with this scope. Most all
come with them. Also due to the high impedance of a scope input if
you do apply to larger voltages it should not damage anything, just
saturate the input.

I think it depends on what parts are connected to that input, inside the
scope. That rating is rather low, so it suggests that some semiconductor
device is the limitation there.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Friday 06 October 2006 08:37 pm, william.kroyer@... wrote:

Why not just get some nice 1% resistors and make a volage divider to add to
the input? You could easily add an external X10 range that way.

That's fine for DC. If there are any cables involved then you need to
compensate for AC effects as well, mostly cable capacitance. Which is what
the typical scope probe compensation adjustments are for.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

Chris,

You can get 10:1 probes. All I've seen have a switch for selecting
times 1 or times 10. Are there probles with this scope. Most all
come with them. Also due to the high impedance of a scope input if
you do apply to larger voltages it should not damage anything, just
saturate the input.

ron


--- In Electronics_101@..., "lcdpublishing"
<lcdpublishing@...> wrote:

How limitting do you think a scope would be if it were limitted to
35 volts?

There is a PC based scope - USB interfaced, that I have been
eyeballing. It isn't cheap, around $300.00, but it is dual

channel

and rated up to 60 Mhz which should be fine for me.

The real kicker that I am liking about the PC scopes is

recording.

For some reason, I think that is important, not sure why, but I

do ;-

)

The drawback is that voltage limit though. While most everything I
check is 5~12 volts, I have checked the output of my Stepper

Driver

and that is at 41 volts.

This is the one that is being considered



Chris

Why not just get some nice 1% resistors and make a volage divider to add to the input? You could easily add an external X10 range that way.

Thought some of you might be interested in the articles listed...

---------- Forwarded Message ----------

Subject: [emrfd] 3 very good articles (understanding resistors, avoiding
ground loops, modeling skin effect in Spice)
Date: Thursday 05 October 2006 06:26 pm
From: topossibilities <topossibilities@...>
To: emrfd@...

EDN on-line has 3 very good articles that I though some of you would be
interested in.

1. Five questions about resistors

Understanding this ubiquitous part can help you avoid common circuit
problems.

The resistor is one of the simpler electronic components. Engineers seldom
examine resistor characteristics until there's a resistor-related problem
with a circuit design. You can probably resolve 90% of these problems after
answering these five key questions:

* How much voltage can I put on the resistor?
* What will be the temperature of the resistor in my circuit?
* How much surge will the resistor withstand?
* What makes a resistor fail?
* How much change in resistance can I expect?

The link for the full article is:




2. Circulating currents...a.k.a. Ground loops.

Understanding how to avoid or minimize the effects of circulating currents
can make your designs more robust. Every engineer should know the techniques
for neutralizing this insidious phenomenon. Article discussion includes
avoiding ground loops in back-panes/PCBs, digital, power supply, audio, RF
and mobile applications.

The link for the full article is:



Modeling skin effect in Spice

3. Skin effect causes increased losses as frequency increases. It also causes
changes in signal velocity, degrading signal fidelity, especially the eye
opening of high-speed data signals on long signal paths on pc boards and
backplanes.

The link for the full article is:



Ed, W1AAZ

Lots of books, parts, kits and test equipment for sale at:



If you don't see what you need, check back (adding items weekly)

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-------------------------------------------------------

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

On Friday 06 October 2006 06:48 pm, lcdpublishing wrote:

How limitting do you think a scope would be if it were limitted to
35 volts?

You're not. (See below.)

There is a PC based scope - USB interfaced, that I have been
eyeballing. It isn't cheap, around $300.00, but it is dual channel
and rated up to 60 Mhz which should be fine for me.

Looking at that, the big question in my mind is the software -- are you
limited to what they supply, and if so does it have to run under windoze?
That would be a definite deal-breaker for me at least. And it looks like it
"requires" w98 at least. :-(

The real kicker that I am liking about the PC scopes is recording.
For some reason, I think that is important, not sure why, but I do ;-
)

The drawback is that voltage limit though. While most everything I
check is 5~12 volts, I have checked the output of my Stepper Driver
and that is at 41 volts.

This is the one that is being considered

Looking at the specs, the input impedance is 1M ohms and under specifications
I find "max. input voltage: 30V (AC + DC)". Now, use a 10:1 probe with
that, as one might typically do with a scope, and you have a much higher
input impedance _and_ voltage range. And it appears that the probes are
included in that price, though even if they weren't I'd think that you could
use what probes you have handy.

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

I dunno, i don't see a problem with verbs in german? Maybe you have an
example to illustrate the point?
Anyway, german and english are extremely similar if you compare them

to

some other languages....

ST

Perhaps something like: Kommen Sie herein <-> You come in

In German the verb (kommen) comes before the subject (Sie) whereas in
English it follows the subject.

But, it's been 43 years since I took 4 years of German and I left
Germany in '67 after a brief stay in Mannheim, compliments of the US
Army. So, I may be very rusty...

Richard