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lk | 5 Sep 19:31

[PIC] TQFP adapter, selfmade.

Hello,

i am wondering if my selfmade TQFP 80 adapter is working well.
Maybe You can just look at the picture and tell me if it is basically 
possible to get it to work with such an adapter.
Of course there are no hazards!
I ve red that the oscillator should be as near to the OSC pins as 
possible. Using that adapter it cant be close at all...
I already have run a simple LED blinking program on that chip, but am 
not sure if everything worked well.
Is there generally the possibility of crosstalk et cetera?
There are not much information i am giving You, but maybe You can give 
me some advise by just looking at the picture.

http://home.arcor.de/luka5/DSC06977.JPG

Regards
Lukas

PS:I hope that this message will not appear twice or more often at the 
piclist. I tried several times to post but without any result...
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Spehro Pefhany | 5 Sep 20:08

Re: [PIC] TQFP adapter, selfmade.

Quoting lk <stowoda <at> gmx.net>:

> Hello,
>
> i am wondering if my selfmade TQFP 80 adapter is working well.
> Maybe You can just look at the picture and tell me if it is basically
> possible to get it to work with such an adapter.
> Of course there are no hazards!
> I ve red that the oscillator should be as near to the OSC pins as
> possible. Using that adapter it cant be close at all...
> I already have run a simple LED blinking program on that chip, but am
> not sure if everything worked well.
> Is there generally the possibility of crosstalk et cetera?
> There are not much information i am giving You, but maybe You can give
> me some advise by just looking at the picture.
>
> http://home.arcor.de/luka5/DSC06977.JPG
>
> Regards
> Lukas

Traces are pretty narrow-- it might be a good idea to widen the Vdd/Vss
traces and maybe add a bypass cap or two near the TQFP, even if you need
to add wire jumpers.

Best regards,
Spehro Pefhany
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Dave Tweed | 5 Sep 21:12

Re: [PIC] TQFP adapter, selfmade.

Spehro Pefhany wrote:
> Quoting lk <stowoda <at> gmx.net>:
> > i am wondering if my selfmade TQFP 80 adapter is working well.
> > Maybe You can just look at the picture and tell me if it is basically
> > possible to get it to work with such an adapter.
> > Of course there are no hazards!
> > I ve red that the oscillator should be as near to the OSC pins as
> > possible. Using that adapter it cant be close at all...
> > I already have run a simple LED blinking program on that chip, but am
> > not sure if everything worked well.
> > Is there generally the possibility of crosstalk et cetera?
> > There are not much information i am giving You, but maybe You can give
> > me some advise by just looking at the picture.
> >
> > http://home.arcor.de/luka5/DSC06977.JPG
> 
> Traces are pretty narrow-- it might be a good idea to widen the Vdd/Vss
> traces and maybe add a bypass cap or two near the TQFP, even if you need
> to add wire jumpers.

Take it a step further than that, even. Instead of a "totally generic"
QFP80 adapter, make one that's specific to the chip (or family of similar
chips) insofar as providing the power and ground connections, bypassing,
crystal/oscillator, reset and a programming connector. This (once debugged)
will make all of these non-issues in any particular application.

You might check out Stuart Ball's article, "Prototyping with QFP Parts",
in Circuit Cellar #218 for further thoughts about this approach:

   http://www.dtweed.com/circuitcellar/caj00218.htm#3698
(Continue reading)

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lk | 5 Sep 22:13

Re: [PIC] TQFP adapter, selfmade.

Dave Tweed schrieb:
> Spehro Pefhany wrote:
>   
>> Quoting lk <stowoda <at> gmx.net>:
>>     
>>> i am wondering if my selfmade TQFP 80 adapter is working well.
>>> Maybe You can just look at the picture and tell me if it is basically
>>> possible to get it to work with such an adapter.
>>> Of course there are no hazards!
>>> I ve red that the oscillator should be as near to the OSC pins as
>>> possible. Using that adapter it cant be close at all...
>>> I already have run a simple LED blinking program on that chip, but am
>>> not sure if everything worked well.
>>> Is there generally the possibility of crosstalk et cetera?
>>> There are not much information i am giving You, but maybe You can give
>>> me some advise by just looking at the picture.
>>>
>>> http://home.arcor.de/luka5/DSC06977.JPG
>>>       
>> Traces are pretty narrow-- it might be a good idea to widen the Vdd/Vss
>> traces and maybe add a bypass cap or two near the TQFP, even if you need
>> to add wire jumpers.
>>     
>
> Take it a step further than that, even. Instead of a "totally generic"
> QFP80 adapter, make one that's specific to the chip (or family of similar
> chips) insofar as providing the power and ground connections, bypassing,
> crystal/oscillator, reset and a programming connector. This (once debugged)
> will make all of these non-issues in any particular application.
>
(Continue reading)

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Jon Baker | 5 Sep 22:40

Re: [PIC] TQFP adapter, selfmade.

2008/9/5 lk <stowoda <at> gmx.net>:
> I can not access the article. There is no link at the site..

It's just an index, I presume you need to buy the back issue.

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Dave Tweed | 5 Sep 23:14

Re: [PIC] TQFP adapter, selfmade.

lk <stowoda <at> gmx.net> wrote:
> Dave Tweed schrieb:
> > You might check out Stuart Ball's article, "Prototyping with QFP Parts",
> > in Circuit Cellar #218 for further thoughts about this approach:
> >
> >    http://www.dtweed.com/circuitcellar/caj00218.htm#3698
>   
> I can not access the article. There is no link at the site..

Sorry, if you don't already have access to the issue, see the links at the
bottom of the page to order a back issue or CDROM.

If you want, I can email you a PDF of the article (757 KB, zipped). Is that
a valid address for off-list mail?

-- Dave Tweed
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lk | 5 Sep 23:20

Re: [PIC] TQFP adapter, selfmade.

Dave Tweed schrieb:
> lk <stowoda <at> gmx.net> wrote:
>   
>> Dave Tweed schrieb:
>>     
>>> You might check out Stuart Ball's article, "Prototyping with QFP Parts",
>>> in Circuit Cellar #218 for further thoughts about this approach:
>>>
>>>    http://www.dtweed.com/circuitcellar/caj00218.htm#3698
>>>       
>>   
>> I can not access the article. There is no link at the site..
>>     
>
> Sorry, if you don't already have access to the issue, see the links at the
> bottom of the page to order a back issue or CDROM.
>
> If you want, I can email you a PDF of the article (757 KB, zipped). Is that
> a valid address for off-list mail?
>
> -- Dave Tweed
>   
Yes You can use this email, i would be grateful.

Lukas
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lk | 5 Sep 22:57

Re: [PIC] TQFP adapter, selfmade.

The PIC18F8680 i am using has no internal oscillator, so i have to get 
another chip to do the test.
The next thing i will do is to redesign the adaptor and add the bypass 
cap, and the smd oscillator.
If i´ll find a way i´ll also try to make vdd/vss thicker as it was 
mentioned before by Sphero Pefhany.

I am not sure if it would be practically to let the adaptor have 2x2 
rows of pinheads.. I have to think about it.
Maybe i gonna use a double sided pcb.

So far, thank You all for Your opinion.

Regards
Lukas

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M. Adam Davis | 5 Sep 20:57

Re: [PIC] TQFP adapter, selfmade.

I don't know what speed you're running at, but if you're using a
crystal faster than 4MHz you should put it closer to the chip - the
TQFP adaptor lines might be too long and introduce too much noise.

Have you already checked each line for shorts and opens?

-Adam

On 9/5/08, lk <stowoda <at> gmx.net> wrote:
> Hello,
>
> i am wondering if my selfmade TQFP 80 adapter is working well.
> Maybe You can just look at the picture and tell me if it is basically
> possible to get it to work with such an adapter.
> Of course there are no hazards!
> I ve red that the oscillator should be as near to the OSC pins as
> possible. Using that adapter it cant be close at all...
> I already have run a simple LED blinking program on that chip, but am
> not sure if everything worked well.
> Is there generally the possibility of crosstalk et cetera?
> There are not much information i am giving You, but maybe You can give
> me some advise by just looking at the picture.
>
> http://home.arcor.de/luka5/DSC06977.JPG
>
> Regards
> Lukas
>
>
> PS:I hope that this message will not appear twice or more often at the
(Continue reading)

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lk | 5 Sep 21:16

Re: [PIC] TQFP adapter, selfmade.

M. Adam Davis schrieb:
> I don't know what speed you're running at, but if you're using a
> crystal faster than 4MHz you should put it closer to the chip - the
> TQFP adaptor lines might be too long and introduce too much noise.
>
> Have you already checked each line for shorts and opens?
>
> -Adam
>
> On 9/5/08, lk <stowoda <at> gmx.net> wrote:
>   
>> Hello,
>>
>> i am wondering if my selfmade TQFP 80 adapter is working well.
>> Maybe You can just look at the picture and tell me if it is basically
>> possible to get it to work with such an adapter.
>> Of course there are no hazards!
>> I ve red that the oscillator should be as near to the OSC pins as
>> possible. Using that adapter it cant be close at all...
>> I already have run a simple LED blinking program on that chip, but am
>> not sure if everything worked well.
>> Is there generally the possibility of crosstalk et cetera?
>> There are not much information i am giving You, but maybe You can give
>> me some advise by just looking at the picture.
>>
>> http://home.arcor.de/luka5/DSC06977.JPG
>>
>> Regards
>> Lukas
>>
(Continue reading)

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