AVR-Chat

HI

I´ve a AVR DRagon and I made a 10 pin flat cable with about 30 cm length ...
well , when I put a ATmega16 or mega32 .. its work fine (I use the AVRSTudio
4.16 build 638), but with ATmega164p the JTAG fail with a message that not
can´t read ... when I use my hand to envolve the flat cable .... Its work
...? Its a EMI ? EMC ???

Anyone have this type of problem ?

Thanks

Emerson Santos


[Non-text portions of this message have been removed]

On Fri, Oct 16, 2009 at 09:22:28AM -0300, Emerson Santos wrote:
> HI
> 
> I?ve a AVR DRagon and I made a 10 pin flat cable with about 30 cm
> length ... well , when I put a ATmega16 or mega32 .. its work fine (I
> use the AVRSTudio 4.16 build 638), but with ATmega164p the JTAG fail
> with a message that not can?t read ... when I use my hand to envolve
> the flat cable .... Its work ...? Its a EMI ? EMC ???
> 
> Anyone have this type of problem ?

Yes. Have had that sort of problem with the Dragon where an ECROS ICE
Cube worked perfectly.

Not sure that just one thing "fixed" my problem but the Dragon behaved
differently for different length of cable. Seemed to work best at 6",
about 14 cm, which was as short as I could make it.

Also put 1/4" thick rubber feet on the bottom of the Dragon to hold it
off the metal top table. Believe that helped but wasn't a complete cure.
The combination of rubber feet and short cable got things working.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.

Hi David

Thanks for you reply

But i can fix the problem soldering a 1K Pull UP in the TCK line of JTAG in
the ATmega164P board ... I don´t see anything about this in the datasheet
but works.

hehehehe

Emerson Santos




2009/10/16 David Kelly <dkelly@hiwaay.net>

>
>
>  On Fri, Oct 16, 2009 at 09:22:28AM -0300, Emerson Santos wrote:
> > HI
> >
> > I?ve a AVR DRagon and I made a 10 pin flat cable with about 30 cm
> > length ... well , when I put a ATmega16 or mega32 .. its work fine (I
> > use the AVRSTudio 4.16 build 638), but with ATmega164p the JTAG fail
> > with a message that not can?t read ... when I use my hand to envolve
> > the flat cable .... Its work ...? Its a EMI ? EMC ???
> >
> > Anyone have this type of problem ?
>
> Yes. Have had that sort of problem with the Dragon where an ECROS ICE
> Cube worked perfectly.
>
> Not sure that just one thing "fixed" my problem but the Dragon behaved
> differently for different length of cable. Seemed to work best at 6",
> about 14 cm, which was as short as I could make it.
>
> Also put 1/4" thick rubber feet on the bottom of the Dragon to hold it
> off the metal top table. Believe that helped but wasn't a complete cure.
> The combination of rubber feet and short cable got things working.
>
> --
> David Kelly N4HHE, dkelly@HiWAAY.net <dkelly%40HiWAAY.net>
> ========================================================================
> Whom computers would destroy, they must first drive mad.
>
> 
>


[Non-text portions of this message have been removed]

On Fri, Oct 16, 2009 at 11:44:53AM -0300, Emerson Santos wrote:
> Hi David
> 
> Thanks for you reply
> 
> But i can fix the problem soldering a 1K Pull UP in the TCK line of
> JTAG in the ATmega164P board ... I don?t see anything about this in
> the datasheet but works.
> 
> hehehehe

Wow! 1k is a pretty stout pullup. I'd experiment with 10k.

Last week I briefly fired up a board via Dragon JTAG that was built a
year ago but never run before. Everything went fine until I attempted to
debug. Board immediately took off running but I can't single step or
breakpoint. Didn't have time or need to pursue it then. Meanwhile a
JTAGICE-II was coming in the mail via Arrow's half price promotion.

Next time I attack that problem board I will have a Dragon, ICE Cube,
and the official JTAG-ICE mkII.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.

David,

You are right on the 10K - if the current needed to pull up is minimal, the Vdrop over that resistor will be minimal and all is well.  But in a high noise environment (or where there is RF floating about), I like to use lower value pull ups if the sink capability of the driver is sufficient.  And 1K at 5V is only 5ma.  Just about anything connected to that line should be able to sink 5ma.  My 2 cents.

73/jeff/ac0c

From: David Kelly 
Sent: Friday, October 16, 2009 10:29 AM
To: AVR-Chat@yahoogroups.com 
Subject: Re: [AVR-Chat] JTAG problems with ATmega164P


  On Fri, Oct 16, 2009 at 11:44:53AM -0300, Emerson Santos wrote:
> Hi David
> 
> Thanks for you reply
> 
> But i can fix the problem soldering a 1K Pull UP in the TCK line of
> JTAG in the ATmega164P board ... I don?t see anything about this in
> the datasheet but works.
> 
> hehehehe

Wow! 1k is a pretty stout pullup. I'd experiment with 10k.

Last week I briefly fired up a board via Dragon JTAG that was built a
year ago but never run before. Everything went fine until I attempted to
debug. Board immediately took off running but I can't single step or
breakpoint. Didn't have time or need to pursue it then. Meanwhile a
JTAGICE-II was coming in the mail via Arrow's half price promotion.

Next time I attack that problem board I will have a Dragon, ICE Cube,
and the official JTAG-ICE mkII.

-- 
David Kelly N4HHE, dkelly@HiWAAY.net
========================================================================
Whom computers would destroy, they must first drive mad.




[Non-text portions of this message have been removed]