Paul Rosen wrote:

> Thank you, Paul for your long answer.
> 
> First I want to say, that my English is not very good. I do not know,
> whether I understood everything correctly. And do not know, whether I
> say everything that way, I want it to say. Sorry for this.

My apologies but, that English is not your first language did not seem
too apparent from your writing. I commend you on your accomplishment.

>>Either your project planning capabilities and project control are very
>>naff or you are dealing with the cutting (or even bleeding) edge
>>technologies. I will stay with the charitable side and consider that
>>you are on the bleeding edge of developments. This then puts you in the
>>realm of prototyping designs or parts of designs to ensure that you
>>achieve the desired performance.
> 
> This is a problem. I am the only designer in our company. The
> possibilities are a bit poor. :-(  I have to solve every problem
> without companion and without assistance.
> 
> What is a naff project contol? Or better: What makes a project control
> the opposite of naff?

"naff" is a coloquial expression (local slang) for dispicably innefective.
The term is rather derogatory but I was not implying that you were in that
particular category.

>>cutting vs bleeding edge
> Could you explain that with other words ... my limited English.
> Sometimes I think, a good equipment makes your thoughts poor. I do not
> really know, which side is better to switch charitable mode on or off.
> ;-)  But the die of PLCC is too hard. Some effects maybe compensated,
> but others not.

"Cutting edge" is in the realm of being so new that it has not been done
before in this context. "Bleeding edge is a more extreme version such that
not only has it not been done before but you are doing it for the first
time as a full production prospect (usually hurts more than the cutting
edge)..

>>OK, so you are already using prototyping boardlets with impedance
>>controlled padding.
> 
> You are speaking from the little PCBs with the controller on it?
> Please, tell me more about "impedance controlled padding".

Often, when prototyping RF circuits, instead of creating a PCB we take
a sheet of plain copper clad board. We mount our devices on small PCB's 
that have only the tracking for pin connection. The distance bewteen the
pin connection tracking and acts like a good capacitor to the massive 
copper ground-plane. The thickness of the PCB on which the pin tracking
is laid and the copper ground-plane is usually such that the characteristic
impedance to ground is 50 ohms. If you have a long route you can usually
tack coaxial links down easily without upsetting this characteristic
impedance. I have used such boardlets up to 2.5GHz in mixed RF and
Digital prototyping.

The companies that make these little boardlets started doing so as a means
to make their own prototyping easier. They then found a market when some of
their engineers moved over to other companies. I will have to dig back in
some quite old notes to find the company's details but having your local
PCB manufacturer make up a batch shouldn't be too hard.

> The analog section is devided from the digital by both grounds, which
> goes closed to the controller as possible. The backside (two layers)
> of the pcb is filled with ground - digital and analog devided to their
> sections.

[%X]

>>Be cognizant of the impedances between layers for your chosen
>>PCB materials.
> 
> Isn't it capacity? Please, tell me more.

Every unit length of track is an inductance. Every pair of parallel
conducting surfaces is more capacitance. Together they form the complex
impedances. Get to know these well.

>>Sounds like youi may need to also consider your decoupling philosophy
>>or your layout toplogies to ensure that you minimise cross-talk and
>>pickup. Take your time doing this.
> 
> I think I do it. Maybe there are some points, which I do not know.I
> use two or more grounds.

Keep analogue and digital ground separate from each other and route both by 
the shortest sensible route. Making the digital ground a full plane on your
digital section of the PCB will reduce the inductance of the copper and
increas the capacitance to the logic supply rails (a good thing).You might
also find that digital capacitive power busbar rails are useful (are these
still around?).

> .... Every section is screened by its own ground.
> Critical signals are double screened with its own signal, hardened by
> an amp and then with its ground. Astral wiring as most as possible..
> Very critical points (high impedance) are devided by gaps in the PCB
> or sometimes wired in the air. In extreme situatuations they are
> sealed from the humidity. I use screen-sheets. I always use
> kelvin-design for critical measurements. I decouple wires with high
> and low current. The thermo effect of a soldering joint is annihilated
> by an inverse one, if disturbing. I take care of the route of every
> lead. I decouple switched high-voltage leads by resistances near to
> the switches, to avoid broadcast. This all for PCB route and real wire
> route. I hope I did not forget anything. Anything more to do?

Sounds like you already have a lot of the right texchniques in place. You
may also like to consider the benefit of adding metal screen cans over some
parts of your circuitry (connected to ground potential) to quieten things
down a bit. I know that it restricts access but adding a few well placed 
test points will assist with troubleshooting without having to remove the
cans.

> But there is the mechanical process equipment, which is not always
> asked me. And sometimes the design of the electronic is made by
> optical aspects. They do not want the electronic to "get cluttered" to
> different places of the equipment, which would be useful for good
> decoupling. And sometimes the mechanical eqipment lets you not do,
> what would be good to avoid crosstalk and pickup. Although this, you
> have to provide a working design. And that could make problems when
> changing a working prototype layout because TQFP. But it helps, what
> you said above.

I suspect that you have considered distributing the separate elements of
the system amongst the equipment to improve signal to noise ratios of the
analogue signals. Where this is possible it will certainlty help. However,
itr does change the architecture of your system and you need to think a
bit about sanity checking the distributed modules.

There are many reasons not to distribute the sensor and contropl elements
of your system. Some of these relate to the environment out on the equipment
(is it very harsh or restricted). You can only resolve that with your 
mechanical colleagues.

>>> And what is about emulation, when the processor is soldered into the
>>> board?
> 
> Still unanswered

I may have missed what you are asking here. I presume you were asking
about the difference between what you see in emulation software (like
PSPICE etc) and the reality of the real components. If this is the
question then the answer is that the models in PSPICE are only based
on the theoretical equivalent circuit network that characterises each
component. The models can be improved if you have better actual or
experimental data that you can trust in a variety of situations. The
better data can take quite a while to develop though so most of us
will consider the supoplied models good enough for most purposes.
However, where you can see a difference between the model and the
actuality you can revisit the model and alter it until it does match
your observed data. I have done this with PSPICE myself for some
IGBT and TRANSORB models that I had to adapt from other less ideal
components.

>>Relax a little more and don't get so flustered. Sit and think a bit
>>more about what you are doing and whether there may be better
>>approaches. I haven't followed this thread from the begining but I
>>am sure that pausing for thought to think what others have said here
>>will help you resolve the problems you feel you are having.
> 
> They said, that I could program the controllers in-curcuit. I know
> that. This helps only for the software, but not for the hardware.

Very true. No amount of programming effort will eliminate the hardware
shortfalls. Get the hardware platform right in terms of stability
although I would expect you to have the major structure (not code) of
your software fairly well planned out already.

> Maybe, I should calm down  But that does not change this fact: The die
> of PLCC makes problems for analog-developement not easier. And I am
> quite safe, that this bothers not only me.

I am sure you are right. With over thirty years of experience in a wide
range of system problems I have come across plenty of problems foist on
the development team by others (not only disti's) We just learn to suck
in a deep breath, count to ten and then just think quietly to ourselves
"here we go again!!". Taking such problems in a calm, collected manner
and working through the individual problems in as logical a process of
elimination as you can muster will lead to you discovering the right
solution to your problems. However, be honest about your problems to
your line management as sometimes they appreciate it (even if they dont
like the news).

To the others, with much shorter responses, I think that you should
offer some real practical advice to Paul Rosen. As one who has not
had any experience with PIC's or Microchip (apart from getting unwanted
mailshots from them) I can only speak in generalities to try to help
him. Mixed signal designs can be real bitches at times and impedance
issues, correct grounding and board layout issues specific to this chip
need to be aired.

-- 
********************************************************************
Paul E. Bennett ....................<email://peb@a...>
Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972 .........NOW AVAILABLE:- HIDECS COURSE......
Tel: +44 (0)1235-811095 .... see http://www.feabhas.com for details.
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************

Paul Rosen wrote:

> Rene Tschaggelar <none@none.net> schrieb:
> 
> Further there is another problem: If you have finished developing with
> the adapted TQFP Controllers, you have to route the PCB new for the
> not adapted series version. And then things change. The audio or the
> measuring is wrong now, because disturbed by the controller. Or the
> application disturbes the processor now and it crashes. 

Careful design ...

> 
> And what is about emulation, when the processor is soldered into the
> board?
> 
> With socketable controllers like PLCC things were much easier. You
> could socket it and change it, when damaged. You could produce the
> developement versions of PCB yourself. Emulation is no problem: Plug
> the emulator into the socket of the controller. And the last
> developement version could without problems be the series version. And
> if you get problems to leave out the socket in the series version, you
> let him be, 

I never used an emulator. They were to expensive to start with and
meanwhile I have debugging techniques that are sufficient.

Rene
-- 
Ing.Buero R.Tschaggelar - http://www.ibrtses.com
& commercial newsgroups - http://www.talkto.net

Paul E. Bennett wrote:

> Paul Rosen wrote:
> 
> 
>>Rene Tschaggelar <none@none.net> schrieb:
>>
>>
>>>What is the problem in creating an application specific board with
>>>everything on that is required for the project ?
>>
>>The problem is, that you do not know before what hardware you need for
>>a project, even in analog-applications. Software and hardware are
>>developed together. You have not only to change the software, but also
>>the hardware. And sometimes you need more than one controller. You
>>cannot use a new board for maybe every 20 versions, because you cannot
>>produce TQFD boards yourself. You have to give it away. And only one
>>PCB is very expensiv and needs much time. If you could produce the PCB
>>yourself, you make some changes in the layout and get a new one in
>>half an hour.


I do make TQFP boards myself. Now also with 0603 parts.
I'm not drilling below 0.7mm or 28mil though.
But also that is doable.

And when I don't like to drill the many holes, I let the board
be done. Depending on the required services I can get
1 dm^2 for 60 Euro or even less withing 3 weeks or even less.


Rene

Jim Granville <no.spam@designtools.co.nz> schrieb:

>Vendors (initially) offer TQFP/SMD only, because that is where the 
>volume business is.
>
>It can, and does, change : examples
>- Cygnal offer selected DIP packages of their MLF production devices
>- Philips original LPC932 family did not include PLCC package, now, they 
>      do.
>- IIRC, Atmels first data on the AT89C51ED2 also excluded PDIP, but now 
>this is included.
>
>So, mention it to Microchip.

To the rehabilitation of Microchip I must say, that they offer
DIP-dsPICs. But this is only possible until 40 leads. The PLCC would
be the better solution, because it is smaller and all the same
reliable contactable. And it has got more leads. 

-- 
Paul dankt den Helfern, 
w&#4294967295;nscht jedem viel Spa&#4294967295; im Usenet
und gr&#4294967295;&#4294967295;t alle, die dies lesen. :-)
Thanks to all usenet-helpers and regards.

Thank you, Paul for your long answer.

First I want to say, that my English is not very good. I do not know,
whether I understood everything correctly. And do not know, whether I
say everything that way, I want it to say. Sorry for this. 

"Paul E. Bennett" <peb@amleth.demon.co.uk> schrieb:

>Either your project planning capabilities and project control are very
>naff or you are dealing with the cutting (or even bleeding) edge
>technologies. I will stay with the charitable side and consider that
>you are on the bleeding edge of developments. This then puts you in the
>realm of prototyping designs or parts of designs to ensure that you
>achieve the desired performance.

This is a problem. I am the only designer in our company. The
possibilities are a bit poor. :-(  I have to solve every problem
without companion and without assistance.

What is a naff project contol? Or better: What makes a project control
the opposite of naff?

>cutting vs bleeding edge
Could you explain that with other words ... my limited English.
Sometimes I think, a good equipment makes your thoughts poor. I do not
really know, which side is better to switch charitable mode on or off.
;-)  But the die of PLCC is too hard. Some effects maybe compensated,
but others not. 

>OK, so you are already using prototyping boardlets with impedance
>controlled padding. 

You are speaking from the little PCBs with the controller on it?
Please, tell me more about "impedance controlled padding".

The analog section is devided from the digital by both grounds, which
goes closed to the controller as possible. The backside (two layers)
of the pcb is filled with ground - digital and analog devided to their
sections. 

>The practice of keeping other component leads
>very short should still apply. Use a small tipped soldering iron but
>as large as your dare (this is all about plenty of heat for very
>short periods of time - mere dabs to connect). 

>If the prototype
>boardlets do not keep the footprint close to what you need for the
>final layout the trim these boardlets down further till they nearly
>fit. 

Very good!! 

>Be cognizant of the impedances between layers for your chosen
>PCB materials.

Isn't it capacity? Please, tell me more.
 
>Sounds like youi may need to also consider your decoupling philosophy
>or your layout toplogies to ensure that you minimise cross-talk and
>pickup. Take your time doing this.

I think I do it. Maybe there are some points, which I do not know.I
use two or more grounds. Every section is screened by its own ground.
Critical signals are double screened with its own signal, hardened by
an amp and then with its ground. Astral wiring as most as possible..
Very critical points (high impedance) are devided by gaps in the PCB
or sometimes wired in the air. In extreme situatuations they are
sealed from the humidity. I use screen-sheets. I always use
kelvin-design for critical measurements. I decouple wires with high
and low current. The thermo effect of a soldering joint is annihilated
by an inverse one, if disturbing. I take care of the route of every
lead. I decouple switched high-voltage leads by resistances near to
the switches, to avoid broadcast. This all for PCB route and real wire
route. I hope I did not forget anything. Anything more to do?

But there is the mechanical process equipment, which is not always
asked me. And sometimes the design of the electronic is made by
optical aspects. They do not want the electronic to "get cluttered" to
different places of the equipment, which would be useful for good
decoupling. And sometimes the mechanical eqipment lets you not do,
what would be good to avoid crosstalk and pickup. Although this, you
have to provide a working design. And that could make problems when
changing a working prototype layout because TQFP. But it helps, what
you said above. 
 
>> And what is about emulation, when the processor is soldered into the
>> board?

Still unanswered
 
>Relax a little more and don't get so flustered. Sit and think a bit
>more about what you are doing and whether there may be better
>approaches. I haven't followed this thread from the begining but I
>am sure that pausing for thought to think what others have said here
>will help you resolve the problems you feel you are having.

They said, that I could program the controllers in-curcuit. I know
that. This helps only for the software, but not for the hardware. 

Maybe, I should calm down  But that does not change this fact: The die
of PLCC makes problems for analog-developement not easier. And I am
quite safe, that this bothers not only me.

-- 
Paul dankt den Helfern, 
w&#4294967295;nscht jedem viel Spa&#4294967295; im Usenet
und gr&#4294967295;&#4294967295;t alle, die dies lesen. :-)
Thanks to all usenet-helpers and regards.

Paul Rosen wrote:
> Hi @ll
> 
> Microchip offers his new controllers (i.e. dsPIC) with > 40 leads only
> in the TQFP but not PLCC package. Sockets for TQFP are not reliable.
> Thus they are no solution.  
> 
> What does that mean? The original PCB cannot longer be used for
> developement, because sockets are not possible. You have to design a
> special PCB for that. 
> 
> The only way I found, is to solder the device under test on a special
> adapter PCB, which fits in a special socket on special designed
> application PCB.
> 
> Are there other possibilities? How do you handle this?

Vendors (initially) offer TQFP/SMD only, because that is where the 
volume business is.

It can, and does, change : examples
- Cygnal offer selected DIP packages of their MLF production devices
- Philips original LPC932 family did not include PLCC package, now, they 
      do.
- IIRC, Atmels first data on the AT89C51ED2 also excluded PDIP, but now 
this is included.

So, mention it to Microchip.

If it is a 'show stopper', choose another uC...

-jg

Rene Tschaggelar <none@none.net> schrieb:

>What is the problem in creating an application specific board with
>everything on that is required for the project ?

The problem is, that you do not know before what hardware you need for
a project, even in analog-applications. Software and hardware are
developed together. You have not only to change the software, but also
the hardware. And sometimes you need more than one controller. You
cannot use a new board for maybe every 20 versions, because you cannot
produce TQFD boards yourself. You have to give it away. And only one
PCB is very expensiv and needs much time. If you could produce the PCB
yourself, you make some changes in the layout and get a new one in
half an hour. 

Further controllers can be damaged, when you have a wild mess of
soldered components. Especiallly audio-design and picoampere/microvolt
measurings and applications with switched high voltage/currents are
very messed, because her special demands of astral routing. 

Because all that I have to solder the TQFP-processor on a special
ilittle board, which can be inserted in the application developement
board. 

Further there is another problem: If you have finished developing with
the adapted TQFP Controllers, you have to route the PCB new for the
not adapted series version. And then things change. The audio or the
measuring is wrong now, because disturbed by the controller. Or the
application disturbes the processor now and it crashes. 

And what is about emulation, when the processor is soldered into the
board?

With socketable controllers like PLCC things were much easier. You
could socket it and change it, when damaged. You could produce the
developement versions of PCB yourself. Emulation is no problem: Plug
the emulator into the socket of the controller. And the last
developement version could without problems be the series version. And
if you get problems to leave out the socket in the series version, you
let him be, 

Even for DS you need a controller, which has the same format in the
development and the series version. And for this purpose PLCC was a
good solution. It is the skimpiest format, that is reliable
socketable. But of all things the DS!!-PIC is not available in this
package. Maybe this shows, that mirochip is new in the
(digital-)analog segment and is not familiar with its problems. 

-- 
Paul dankt den Helfern, 
w&#4294967295;nscht jedem viel Spa&#4294967295; im Usenet
und gr&#4294967295;&#4294967295;t alle, die dies lesen. :-)
Thanks to all usenet-helpers and regards.

Paul Rosen wrote:

> Rene Tschaggelar <none@none.net> schrieb:
> 
>>What is the problem in creating an application specific board with
>>everything on that is required for the project ?
> 
> The problem is, that you do not know before what hardware you need for
> a project, even in analog-applications. Software and hardware are
> developed together. You have not only to change the software, but also
> the hardware. And sometimes you need more than one controller. You
> cannot use a new board for maybe every 20 versions, because you cannot
> produce TQFD boards yourself. You have to give it away. And only one
> PCB is very expensiv and needs much time. If you could produce the PCB
> yourself, you make some changes in the layout and get a new one in
> half an hour.

Either your project planning capabilities and project control are very
naff or you are dealing with the cutting (or even bleeding) edge
technologies. I will stay with the charitable side and consider that
you are on the bleeding edge of developments. This then puts you in the
realm of prototyping designs or parts of designs to ensure that you
achieve the desired performance.

> Further controllers can be damaged, when you have a wild mess of
> soldered components. Especially audio-design and picoampere/microvolt
> measurings and applications with switched high voltage/currents are
> very messed, because her special demands of astral routing.
> 
> Because all that I have to solder the TQFP-processor on a special
> ilittle board, which can be inserted in the application developement
> board.

OK, so you are already using prototyping boardlets with impedance
controlled padding. The practice of keeping other component leads
very short should still apply. Use a small tipped soldering iron but
as large as your dare (this is all about plenty of heat for very
short periods of time - mere dabs to connect). If the prototype
boardlets do not keep the footprint close to what you need for the
final layout the trim these boardlets down further till they nearly
fit. Be cognizant of the impedances between layers for your chosen
PCB materials.

> Further there is another problem: If you have finished developing with
> the adapted TQFP Controllers, you have to route the PCB new for the
> not adapted series version. And then things change. The audio or the
> measuring is wrong now, because disturbed by the controller. Or the
> application disturbes the processor now and it crashes.

Sounds like youi may need to also consider your decoupling philosophy
or your layout toplogies to ensure that you minimise cross-talk and
pickup. Take your time doing this.

> And what is about emulation, when the processor is soldered into the
> board?
> 
> With socketable controllers like PLCC things were much easier. You
> could socket it and change it, when damaged. You could produce the
> developement versions of PCB yourself. Emulation is no problem: Plug
> the emulator into the socket of the controller. And the last
> developement version could without problems be the series version. And
> if you get problems to leave out the socket in the series version, you
> let him be,
> 
> Even for DS you need a controller, which has the same format in the
> development and the series version. And for this purpose PLCC was a
> good solution. It is the skimpiest format, that is reliable
> socketable. But of all things the DS!!-PIC is not available in this
> package. Maybe this shows, that mirochip is new in the
> (digital-)analog segment and is not familiar with its problems.
> 

Relax a little more and don't get so flustered. Sit and think a bit
more about what you are doing and whether there may be better
approaches. I haven't followed this thread from the begining but I
am sure that pausing for thought to think what others have said here
will help you resolve the problems you feel you are having.

-- 
********************************************************************
Paul E. Bennett ....................<email://peb@a...>
Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972 .........NOW AVAILABLE:- HIDECS COURSE......
Tel: +44 (0)1235-811095 .... see http://www.feabhas.com for details.
Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
********************************************************************