Question About IC Chips

[CJT]

John Fields wrote:

On Tue, 29 Mar 2005 13:42:40 -0500 (EST), "Aidan Grey"
apgrey@nospam.con> wrote:


On Mon, 28 Mar 2005 23:09:00 GMT, elehman1@columbus.rr.com wrote:


Sorry for my typing skills. I ment to say:

What do you do with unused pins?

elehman1@columbus.rr.com> wrote in message
news:STR1e.21517$rL3.11988@fe2.columbus.rr.com...

Should the used pins be left unconnected or should they be taken to

ground?



Unused inputs should be tied to either VCC or ground. If they are left
open, it is possible the chip will start "oscillating", if the input is
moving
between on and off. This will probably not affect the chip, but may cause
odd problems elsewhere in the circuit.

At one time, it was the military practise to attach unused inputs through
a 1K resister to VCC. Doing this is longer thought necessary, just attach it
directly.


---
That's true except for multiple-emitter TTL, in which case the
resistor should be added if the input is pulled high. It's all
spelled out here:

http://focus.ti.com/lit/an/sdya009c/sdya009c.pdf

There is, however, the curious note on the bottom of page 7...

The one about outputs?

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

 

[John Fields]

On Wed, 30 Mar 2005 01:12:58 GMT, CJT <abujlehc@prodigy.net> wrote:

John Fields wrote:

There is, however, the curious note on the bottom of page 7...



The one about outputs?

Duh?

--
John Fields
Professional Circuit Designer

 

[Joel Kolstad]

"John Fields" <jfields@austininstruments.com> wrote in message
news:d1rj41pr25d361bnaajbddn6c6ms43oq5n@4ax.com...

I disagree. Resistors not needed for a specific reason represent
money wasted, (a penny wasted on each of a million units is $10,000 of
lost revenue!) and any designer worth his salt needs to learn how to
work without that expensive a net.

Sure John, but there are plenty of us here who are lucky to see 1000 units
of what we design go into production, much less a million. I think a better
approach is to spend the extra pennies on the first 1000 units to get the
'time to market' advantage as well as having effectively bought 'insurance'
that the design will work, and then -- if time permits -- go back and start
cost minimizing.

I also find there are usually much bigger fish to fry than saving the price
of an extra resistor or capacitor here of there... things like someone using
a very high end DSP to perform a function that a dedicated FPGA and a
microcontroller could do for 1/4 the price, using a much faster processor
than needed because they don't have a good algorithm for what they want to
do (which can also quickly lead to, e.g., bigger batteries!), etc.

I've worked places where we'd spend something like $10,000 on chrome-plated
stainless steel 'skins' for the machines we were building; it was really
hard to get that excited about saving $10 on some $300 PCBs that went into
it... (On the other hand, that machine also had a $40,000 air-bearing
stage, and we DID sit around spending time trying to cost reduce _it_!)

 

[CJT]

John Fields wrote:

On Wed, 30 Mar 2005 01:12:58 GMT, CJT <abujlehc@prodigy.net> wrote:


John Fields wrote:


There is, however, the curious note on the bottom of page 7...



The one about outputs?


Duh?

Presumably they don't think a lot of unloaded outputs ringing away is a
good idea.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form che...@prodigy.net.

 

[Terry Given]

Joel Kolstad wrote:

"John Fields" <jfields@austininstruments.com> wrote in message
news:d1rj41pr25d361bnaajbddn6c6ms43oq5n@4ax.com...

I disagree. Resistors not needed for a specific reason represent
money wasted, (a penny wasted on each of a million units is $10,000 of
lost revenue!) and any designer worth his salt needs to learn how to
work without that expensive a net.


Sure John, but there are plenty of us here who are lucky to see 1000 units
of what we design go into production, much less a million. I think a better
approach is to spend the extra pennies on the first 1000 units to get the
'time to market' advantage as well as having effectively bought 'insurance'
that the design will work, and then -- if time permits -- go back and start
cost minimizing.

I also find there are usually much bigger fish to fry than saving the price
of an extra resistor or capacitor here of there... things like someone using
a very high end DSP to perform a function that a dedicated FPGA and a
microcontroller could do for 1/4 the price, using a much faster processor
than needed because they don't have a good algorithm for what they want to
do (which can also quickly lead to, e.g., bigger batteries!), etc.

I've worked places where we'd spend something like $10,000 on chrome-plated
stainless steel 'skins' for the machines we were building; it was really
hard to get that excited about saving $10 on some $300 PCBs that went into
it... (On the other hand, that machine also had a $40,000 air-bearing
stage, and we DID sit around spending time trying to cost reduce _it_!)

I can recount dozens of similar stories. My favourite is this one:

A little drive (<= 2.2kW) we made was designed to be very cheap. After
the basic design was up and running, a buddy of mine was tasked with the
cost-redecution exercise. He spent many weeks at the task, ripping out
parts wholesale - why use 1% when 10% will do, etc. One particular
cost-reduction involved replacing some important 100nF film caps with
Z5U, and all 10 prototypes *exploded* within an hour, but thats a whole
'nother story. The outcome was a reduction of around $4 to $35 worth of
electronics - a sizeable chunk, and well worth implementing, which we
duly did.

Not long after, the marketing powers-that-be decided the original brown
cardboard box with black writing wasnt good enough, and that a fancy,
shiny cardboard box with 6 colours was required instead. They also
decided head office would sell the product thru a wholesale outlet it
owned, rather than us doing it. This box was $7 *more* than the original
box, and they had a minimum run size of 30,000 boxes. So they bought
them, marked with the wholesalers details. Several years later, after
only selling a couple of thousand drives thru head office, we took the
product off them, and sold it ourselves. We of course had to place big
stickers over the (now incorrect) company details on the pretty boxes,
at a cost of about $1 per box. After a few more years we obsoleted the
design, at which point we *still* had about 20,000 of these useless
bloody cardboard boxes.

When we designed the replacement product, we didnt even bother trying to
do a similar cost-reduction by shaving off $0.01 parts. Instead we
concentrated on time-to-assemble, and reduced it from an hour to 3
minutes. This allowed us to spend $35 on a user interface and $20 on a
micro, yet have a build cost slightly lower than the product we
replaced. The cardboard box was cheap and plain brown with black writing....

although we did discover a problem with the box. In the first 3 months
of the new products life, we got a dozen or more (from several thousand)
back with smashed plastic - shipping damage. Our mechanical engineer had
to drop the box onto a corner from > 2m to make them break (spec was
surviving 1m drop test onto concrete). It turned out that for the
smaller drives the package was about the right size to grab in one hand
and throw into a delivery van.....rather than implement my suggestion
(1kg of concrete in each box) Mike beefed up the cardboard so it would
pass a 3m drop test.

Cheers
Terry

 

[John Fields]

On Wed, 30 Mar 2005 04:07:45 GMT, CJT <abujlehc@prodigy.net> wrote:

John Fields wrote:
On Wed, 30 Mar 2005 01:12:58 GMT, CJT <abujlehc@prodigy.net> wrote:


John Fields wrote:


There is, however, the curious note on the bottom of page 7...



The one about outputs?


Duh?


Presumably they don't think a lot of unloaded outputs ringing away is a
good idea.

---
I think it's just an error, where:

"Unused outputs of a device should not be left unconnected (open)."

should read:

"Unused outputs of a device should be left unconnected (open)."

in order to agree with the figure.

--
John Fields
Professional Circuit Designer

 

[repatch]

On Tue, 29 Mar 2005 18:14:14 -0600, John Fields wrote:

On Tue, 29 Mar 2005 16:17:31 -0500, repatch <repatch42@yahoo.com> wrote:

On Tue, 29 Mar 2005 13:42:40 -0500, Aidan Grey wrote:


Unused inputs should be tied to either VCC or ground. If they are
left
open, it is possible the chip will start "oscillating", if the input is
moving
between on and off. This will probably not affect the chip, but may
cause odd problems elsewhere in the circuit.

At one time, it was the military practise to attach unused inputs
through
a 1K resister to VCC. Doing this is longer thought necessary, just
attach it directly.

Right, and everything will be fine, until a new program is uploaded that
zeros the tris bit for port a, when he/she meant port b... let's just say
leaving it floating is a FAR better result...

The resistor is still necessary IMHO, if only to save a person from their
own mistakes.

I disagree. Resistors not needed for a specific reason represent money
wasted, (a penny wasted on each of a million units is $10,000 of lost
revenue!) and any designer worth his salt needs to learn how to work
without that expensive a net.

Obviously there are cases where the extra cent won't make it worthwhile.

But consider this: what if YOU are not the programmer working on the
device? Things change, people change. It's very likely that firmware will
be changed by someone else, someone who may not have the experience,
someone who test benches new firmware, notes everything is fine, releases
the firmware to the field, and all of a sudden hundreds of dead devices
are being returned. Why? The specific conditions that set the port to zero
(when tied to one, or vice versa) were never seen during this
inexperienced programmers testing.

Consider the costs then??

Or consider this: MCUs aren't infallible, do ugly things to the power
rails or expose them to ESD and it's very possible for the port direction
control bits to flip. Even strong RF can do it.

It's a pointless debate anyways, some people are comfortable with the risk
and will go for it, and there are reasons to choose that route. But unless
you have a VERY specific reason NOT to include the resistors (cost, space,
etc.) I would include it even on a product in high volume. A fraction of a
cent per product is much cheaper then a rash of RMAs, plus the damage to
your company's reputation.

 

[John Fields]

On Wed, 30 Mar 2005 10:30:33 -0500, repatch <repatch42@yahoo.com>
wrote:

On Tue, 29 Mar 2005 18:14:14 -0600, John Fields wrote:

On Tue, 29 Mar 2005 16:17:31 -0500, repatch <repatch42@yahoo.com> wrote:

On Tue, 29 Mar 2005 13:42:40 -0500, Aidan Grey wrote:


Unused inputs should be tied to either VCC or ground. If they are
left
open, it is possible the chip will start "oscillating", if the input is
moving
between on and off. This will probably not affect the chip, but may
cause odd problems elsewhere in the circuit.

At one time, it was the military practise to attach unused inputs
through
a 1K resister to VCC. Doing this is longer thought necessary, just
attach it directly.

Right, and everything will be fine, until a new program is uploaded that
zeros the tris bit for port a, when he/she meant port b... let's just say
leaving it floating is a FAR better result...

The resistor is still necessary IMHO, if only to save a person from their
own mistakes.

I disagree. Resistors not needed for a specific reason represent money
wasted, (a penny wasted on each of a million units is $10,000 of lost
revenue!) and any designer worth his salt needs to learn how to work
without that expensive a net.

Obviously there are cases where the extra cent won't make it worthwhile.

But consider this: what if YOU are not the programmer working on the
device? Things change, people change. It's very likely that firmware will
be changed by someone else, someone who may not have the experience,
someone who test benches new firmware, notes everything is fine, releases
the firmware to the field, and all of a sudden hundreds of dead devices
are being returned. Why? The specific conditions that set the port to zero
(when tied to one, or vice versa) were never seen during this
inexperienced programmers testing.

---
If I've designed a piece of equipment for a client, and it works like
it's supposed to, then I've done my job and everyone is happy. If,
then, someone comes along behing me and starts trying to make changes
without knowing what they're doing, it certainly doesn't reflect
badly on me, it reflects badly on whoever was supervising the idiot
programmer.
---

Consider the costs then??

---
Why should I care? I didn't have anything to do with the failures.
---

Or consider this: MCUs aren't infallible, do ugly things to the power
rails or expose them to ESD and it's very possible for the port direction
control bits to flip. Even strong RF can do it.

---
So what? If those are eventualities which are to be expected in the
field, then the proper time to address them is during the design, and
if it's prudent to add pullups or pulldowns it should be done as part
of the process, but certainly not blindly, and _cedrtainly_ not
because some idiot may come along and screw with your code.
---

It's a pointless debate anyways, some people are comfortable with the risk
and will go for it, and there are reasons to choose that route. But unless
you have a VERY specific reason NOT to include the resistors (cost, space,
etc.) I would include it even on a product in high volume. A fraction of a
cent per product is much cheaper then a rash of RMAs, plus the damage to
your company's reputation.

---
The damage to the company's repuation would have come from the idiot
programmer's work not having been supervised closely enough, not from
any hardware design fault on my part.

--
John Fields
Professional Circuit Designer

 

[John Woodgate]

I read in alt.binaries.schematics.electronic that John Fields
<jfields@austininstruments.com> wrote (in
<l4kl41t0jto9js298hfttgqaa8ufoajcp8@4ax.com&gt about 'Question About IC
Chips', on Wed, 30 Mar 2005:

The damage to the company's repuation would have come from the idiot
programmer's work not having been supervised closely enough, not from
any hardware design fault on my part.

But you've moved on, whereas he has a clear field to explain to the CEO
that 'The designer didn't take standard precautions against unforeseen,
but reasonably foreseeable, events. This was a disaster waiting to
happen.'

This thread is spread across six newsgroups. Is that really necessary?
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Stewart Pinkerton]

On Wed, 30 Mar 2005 18:10:58 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in alt.binaries.schematics.electronic that John Fields
jfields@austininstruments.com> wrote (in
l4kl41t0jto9js298hfttgqaa8ufoajcp8@4ax.com&gt about 'Question About IC
Chips', on Wed, 30 Mar 2005:

The damage to the company's repuation would have come from the idiot
programmer's work not having been supervised closely enough, not from
any hardware design fault on my part.

But you've moved on, whereas he has a clear field to explain to the CEO
that 'The designer didn't take standard precautions against unforeseen,
but reasonably foreseeable, events. This was a disaster waiting to
happen.'

This thread is spread across six newsgroups. Is that really necessary?

Sure it is, because Fields is desperate to cover his idiot arse!
*Good* designers think about what might go wrong, not just what the
circuit will do if everything is perfect. It's analogous to software
error-trapping.

As you rightly say, 'standard precautions against reasonably
foreseeable events'.

Stewart Pinkerton - professional hardware design engineer

No, I wouldn't really use a pretentious sig like that, because I
actually am one..........................
--

Stewart Pinkerton | Music is Art - Audio is Engineering

 

[Terry Given]

Stewart Pinkerton wrote:

On Wed, 30 Mar 2005 18:10:58 +0100, John Woodgate
jmw@jmwa.demon.contraspam.yuk> wrote:


I read in alt.binaries.schematics.electronic that John Fields
jfields@austininstruments.com> wrote (in
l4kl41t0jto9js298hfttgqaa8ufoajcp8@4ax.com&gt about 'Question About IC
Chips', on Wed, 30 Mar 2005:


The damage to the company's repuation would have come from the idiot
programmer's work not having been supervised closely enough, not from
any hardware design fault on my part.

But you've moved on, whereas he has a clear field to explain to the CEO
that 'The designer didn't take standard precautions against unforeseen,
but reasonably foreseeable, events. This was a disaster waiting to
happen.'

This thread is spread across six newsgroups. Is that really necessary?


Sure it is, because Fields is desperate to cover his idiot arse!
*Good* designers think about what might go wrong, not just what the
circuit will do if everything is perfect. It's analogous to software
error-trapping.

As you rightly say, 'standard precautions against reasonably
foreseeable events'.

Stewart Pinkerton - professional hardware design engineer

No, I wouldn't really use a pretentious sig like that, because I
actually am one..........................

I tend to agree with John Fields on this one, mostly because a lot of my
work has had stringent budget constraints. A suitable compromise would
be to attach notes to the schematic and code (eg SFR values) pointing
out the steps taken and the potential ramifications.

A far more likely scenario is that the software doesnt work properly in
the first place. Hardware that cant tolerate software going apeshit is a
definite cause for concern.

AFA SFR bit-flipping is concerned, the paranoid programmer re-loads SFRs
every interrupt, just in case. This precautionary measure, unlike using
resistors, costs only a tiny amount of development time; unit build cost
is zero.

Cheers
Terry

 

[John Fields]

On Wed, 30 Mar 2005 19:43:37 +0000 (UTC), Stewart Pinkerton
<patent3@dircon.co.uk> wrote:

On Wed, 30 Mar 2005 18:10:58 +0100, John Woodgate
jmw@jmwa.demon.contraspam.yuk> wrote:

I read in alt.binaries.schematics.electronic that John Fields
jfields@austininstruments.com> wrote (in
l4kl41t0jto9js298hfttgqaa8ufoajcp8@4ax.com&gt about 'Question About IC
Chips', on Wed, 30 Mar 2005:

The damage to the company's repuation would have come from the idiot
programmer's work not having been supervised closely enough, not from
any hardware design fault on my part.

But you've moved on, whereas he has a clear field to explain to the CEO
that 'The designer didn't take standard precautions against unforeseen,
but reasonably foreseeable, events. This was a disaster waiting to
happen.'

This thread is spread across six newsgroups. Is that really necessary?

Sure it is, because Fields is desperate to cover his idiot arse!

---
That makes absolutely _no_ sense. If I was wrong about something, how
would I be covering my ass by broadcasting it to an ever-increasing
audience?
---

*Good* designers think about what might go wrong, not just what the
circuit will do if everything is perfect. It's analogous to software
error-trapping.

As you rightly say, 'standard precautions against reasonably
foreseeable events'.

---
Well, dumbfuck, if you'd bothered to have read all of the thread
before firing off one of your mealy-mouthed epithets you might,
perhaps, have noticed that I didn't unequivocally state that pullups
should never be used, I said they should be used when their inclusion
in the circuit is warranted. Simple. waste not, want not.
---

Stewart Pinkerton - professional hardware design engineer

---
After reviewing that "KISASS" monstrosity and that bloated _800K_
sketch on which it lives, I'm sure when you refer to hardware you mean
hammers and pliars and those sorts of things, no?

--
John Fields
Professional Circuit Designer

 

[repatch]

On Wed, 30 Mar 2005 15:58:56 -0600, John Fields wrote:

Well, dumbfuck, if you'd bothered to have read all of the thread before

Ahh, now I understand. You are one of those people who troll newsgroups
and start flame wars. And then, when backed into a corner where their
point of view is clearly not viable, resorts to foul language and juvenile
insults...

Sorry to everyone else for contributing to this person's sorry game.

And plonk to you Mr. Fields.

 

[John Woodgate]

I read in alt.binaries.schematics.electronic that repatch
<repatch42@yahoo.com> wrote (in
<pan.2005.03.31.03.09.49.149186@yahoo.com&gt about 'Question About IC
Chips', on Wed, 30 Mar 2005:

On Wed, 30 Mar 2005 15:58:56 -0600, John Fields wrote:

Well, dumbfuck, if you'd bothered to have read all of the thread before

Ahh, now I understand. You are one of those people who troll newsgroups
and start flame wars. And then, when backed into a corner where their
point of view is clearly not viable, resorts to foul language and juvenile
insults...

Sorry to everyone else for contributing to this person's sorry game.

And plonk to you Mr. Fields.

Don't rush to judgement in this case. Someone else involved has a
'past'.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[John Fields]

On Wed, 30 Mar 2005 22:06:22 -0500, repatch <repatch42@yahoo.com>
wrote:

If all you care about is doing it your way, and that your way seems to
work, so be it. The fact that you don't CARE that your way may result in
problems in the future, even though they are not directly your fault...
well that's just scary.

---
I'll stand behind everything I do and take full responsibility for it,
but when someone starts messing with my stuff, then the guarantee
expires. It's very simple, but obviously very difficult for crybabies
like you, who need to have their asses continually wiped for them to
understand.

--
John Fields
Professional Circuit Designer

 

[John Fields]

On Wed, 30 Mar 2005 22:09:51 -0500, repatch <repatch42@yahoo.com>
wrote:

On Wed, 30 Mar 2005 15:58:56 -0600, John Fields wrote:

Well, dumbfuck, if you'd bothered to have read all of the thread before

Ahh, now I understand. You are one of those people who troll newsgroups
and start flame wars. And then, when backed into a corner where their
point of view is clearly not viable, resorts to foul language and juvenile
insults...

Sorry to everyone else for contributing to this person's sorry game.

And plonk to you Mr. Fields.

---
My pleasure.

--
John Fields
Professional Circuit Designer

 

[Stewart Pinkerton]

On Thu, 31 Mar 2005 04:31:46 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Wed, 30 Mar 2005 22:06:22 -0500, repatch <repatch42@yahoo.com
wrote:


If all you care about is doing it your way, and that your way seems to
work, so be it. The fact that you don't CARE that your way may result in
problems in the future, even though they are not directly your fault...
well that's just scary.

---
I'll stand behind everything I do and take full responsibility for it,
but when someone starts messing with my stuff, then the guarantee
expires. It's very simple, but obviously very difficult for crybabies
like you, who need to have their asses continually wiped for them to
understand.

As noted, *good* designers allow for what *could* happen to their
circuits under sub-optimal circumstances. 'John Fields' filed under
'do not employ'...................

--

Stewart Pinkerton | Music is Art - Audio is Engineering

 

[John Fields]

On Thu, 31 Mar 2005 17:11:19 +0000 (UTC), Stewart Pinkerton
<patent3@dircon.co.uk> wrote:

On Thu, 31 Mar 2005 04:31:46 -0600, John Fields
jfields@austininstruments.com> wrote:

On Wed, 30 Mar 2005 22:06:22 -0500, repatch <repatch42@yahoo.com
wrote:


If all you care about is doing it your way, and that your way seems to
work, so be it. The fact that you don't CARE that your way may result in
problems in the future, even though they are not directly your fault...
well that's just scary.

---
I'll stand behind everything I do and take full responsibility for it,
but when someone starts messing with my stuff, then the guarantee
expires. It's very simple, but obviously very difficult for crybabies
like you, who need to have their asses continually wiped for them to
understand.

As noted, *good* designers allow for what *could* happen to their
circuits under sub-optimal circumstances. 'John Fields' filed under
'do not employ'...................

---
Heh... Like what you say matters? ALL the stuff I get paid for works,
my clients are happy campers, and when they want modifications or
changes, guess what? They call _me_ because they know the work will
be done carefully and properly.

You, on the other hand, seem to blithely advocate the blind peppering
of pullups everywhere, whether they're needed or not, just because
that gives you the warm fuzzies. Pure waste and idiocy as far as I'm
concerned.

Just for grins, think about this: Say that you've designed a piece of
equipment using Pinkerton's Rule, (which mandates that pullups be hung
from every possible port) and that even though it wasn't designed to
operate in a high-EMI environment, it nonetheless finds itself in one.

Now, depending on the locations of the pullups and the length of trace
between them and their associated ports, the pullups could do more
harm than good. So now, by not having considered the possibility that
your equipment might be taken into a high-EMI environment and then,
during the design, taking whatever measures necessary to make it
immune from EMI you must admit that you didn't execute the design
properly and, therefore, come to the conclusion that you are a bad
designer.

--
John Fields
Professional Circuit Designer

 

[John Fields]

On Thu, 31 Mar 2005 20:56:08 +0000 (UTC), Stewart Pinkerton
<patent3@dircon.co.uk> wrote:

On Thu, 31 Mar 2005 12:06:12 -0600, John Fields
jfields@austininstruments.com> wrote:

On Thu, 31 Mar 2005 17:11:19 +0000 (UTC), Stewart Pinkerton
patent3@dircon.co.uk> wrote:

On Thu, 31 Mar 2005 04:31:46 -0600, John Fields
jfields@austininstruments.com> wrote:

On Wed, 30 Mar 2005 22:06:22 -0500, repatch <repatch42@yahoo.com
wrote:


If all you care about is doing it your way, and that your way seems to
work, so be it. The fact that you don't CARE that your way may result in
problems in the future, even though they are not directly your fault...
well that's just scary.

---
I'll stand behind everything I do and take full responsibility for it,
but when someone starts messing with my stuff, then the guarantee
expires. It's very simple, but obviously very difficult for crybabies
like you, who need to have their asses continually wiped for them to
understand.

As noted, *good* designers allow for what *could* happen to their
circuits under sub-optimal circumstances. 'John Fields' filed under
'do not employ'...................

---
Heh... Like what you say matters? ALL the stuff I get paid for works,
my clients are happy campers, and when they want modifications or
changes, guess what? They call _me_ because they know the work will
be done carefully and properly.

You, on the other hand, seem to blithely advocate the blind peppering
of pullups everywhere, whether they're needed or not, just because
that gives you the warm fuzzies. Pure waste and idiocy as far as I'm
concerned.

Just for grins, think about this: Say that you've designed a piece of
equipment using Pinkerton's Rule, (which mandates that pullups be hung
from every possible port) and that even though it wasn't designed to
operate in a high-EMI environment, it nonetheless finds itself in one.

Now, depending on the locations of the pullups and the length of trace
between them and their associated ports, the pullups could do more
harm than good. So now, by not having considered the possibility that
your equipment might be taken into a high-EMI environment and then,
during the design, taking whatever measures necessary to make it
immune from EMI you must admit that you didn't execute the design
properly and, therefore, come to the conclusion that you are a bad
designer.

So, you agree that all likely abuses of your design should be taken
into consideration before you sign it off. Thanks for your admission
that you're an incompetent asshole.

---

Damn, but you're dense, Pinkerton. I've never said that all likely
abuses _shouldn't_ be taken into consideration, all I said is that
there are limits, and the example I gave above was to prove a point;
namely, that by indiscriminately shoving crap into a design because it
makes you think that you've smugly covered all bases, you'll not only
make build costs higher, you could very well be buying yourself
trouble downstream because you didn't (or, in your case, _couldn't_)
consider one of the consequences of your misguided design philosophy.
As for the "Thanks for your admission that you're an incompetent
asshole." part, I can only assume that since you didn't have a valid
argument you had to revert to subterfuge and crudity in order to try
to derail the thread. Well, I'll have you know we run a fine,
upstanding newsgroup here and we don't appreciate that kind of cheesy
behavior from rat-hole residents like you who come over here looking
for handouts and spare change, harrumpff!!!

--
John Fields
Professional Circuit Designer

 

[Watson A.Name - \"Watt Su]

"John Fields" <jfields@austininstruments.com> wrote in message
news:q4do419gutodepfribn7da0ospvmf8bk11@4ax.com...

On Thu, 31 Mar 2005 17:11:19 +0000 (UTC), Stewart Pinkerton
patent3@dircon.co.uk> wrote:

On Thu, 31 Mar 2005 04:31:46 -0600, John Fields
jfields@austininstruments.com> wrote:

On Wed, 30 Mar 2005 22:06:22 -0500, repatch <repatch42@yahoo.com
wrote:


If all you care about is doing it your way, and that your way seems
to
work, so be it. The fact that you don't CARE that your way may
result in
problems in the future, even though they are not directly your
fault...
well that's just scary.

---
I'll stand behind everything I do and take full responsibility for
it,
but when someone starts messing with my stuff, then the guarantee
expires. It's very simple, but obviously very difficult for
crybabies
like you, who need to have their asses continually wiped for them to
understand.

As noted, *good* designers allow for what *could* happen to their
circuits under sub-optimal circumstances. 'John Fields' filed under
'do not employ'...................

---
Heh... Like what you say matters? ALL the stuff I get paid for works,
my clients are happy campers, and when they want modifications or
changes, guess what? They call _me_ because they know the work will
be done carefully and properly.

You, on the other hand, seem to blithely advocate the blind peppering
of pullups everywhere, whether they're needed or not, just because

You'll have to ignore J.F.'s rants. I caught him leaving out a pullup
once, and he got all pi$$ed off at me and cursed me out.

I'll have to keep on him about that. [snip]

properly and, therefore, come to the conclusion that you are a bad
designer.

He speaks from experience. ;-0

--
John Fields
Professional Circuit Designer