AVR using JTag pins

Hi,

Could I use AVR JTag pins in my application circuit when debugging using JTag?

Adding resistors to separate?

Thanks!

These comments are intended to be my own opinion and they
may, or may not be shared by my employer, Atmel Sweden.

"terry" <leonlai2k@yahoo.com> skrev i meddelandet
news:9904d48.0410311817.46d7435c@posting.google.com...
> Hi,
>
> Could I use AVR JTag pins in my application circuit when debugging using
JTag?
>
> Adding resistors to separate?
>
> Thanks!

I do not think so.
-- 
Best Regards
Ulf at atmel dot com

"Ulf Samuelsson" <ulf@NOSPAMatmel.com> wrote in message news:<cm8bte$t49$3@public2.atmel-nantes.fr>...
> These comments are intended to be my own opinion and they
> may, or may not be shared by my employer, Atmel Sweden.
> 
> "terry" <leonlai2k@yahoo.com> skrev i meddelandet
> news:9904d48.0410311817.46d7435c@posting.google.com...
> > Hi,
> >
> > Could I use AVR JTag pins in my application circuit when debugging using
>  JTag?
> >
> > Adding resistors to separate?
> >
> > Thanks!
> 
> I do not think so.

So I cannot debug when I use SPI in ATMega16!

terry wrote:

> So I cannot debug when I use SPI in ATMega16!

On the ATmega16, the SPI port is on PB4-7 and the debug port in on port 
PC2-5.

What is the problem again ???

Yes, you will lose port bits PC2-5 when using the JTAG port.


hamilton

hamilton <hamilton@deminsional.com> wrote in message news:<418cf18e_4@omega.dimensional.com>...
> terry wrote:
> 
> > So I cannot debug when I use SPI in ATMega16!
> 
> On the ATmega16, the SPI port is on PB4-7 and the debug port in on port 
> PC2-5.
> 
> What is the problem again ???
> 
> Yes, you will lose port bits PC2-5 when using the JTAG port.
> 
> 
> hamilton

Thanks!

hamilton <hamilton@deminsional.com> wrote in message news:<418cf18e_4@omega.dimensional.com>...
> terry wrote:
> 
> > So I cannot debug when I use SPI in ATMega16!
> 
> On the ATmega16, the SPI port is on PB4-7 and the debug port in on port 
> PC2-5.
> 
> What is the problem again ???
> 
> Yes, you will lose port bits PC2-5 when using the JTAG port.
> 
> 
> hamilton

I found in the JTagIce manual there is a section saying the following:

Figure 2-2 shows which JTAG lines should be connected to the target
AVR to ensure correct operation. To avoid drive contention on the
lines, place series resistors between the JTAG lines and external
circuitry. The value of the resistor should not exceed the maximum
ratings and sink or source to much current. See Section 5.4 for a
detailed description of the hardware.

Is it true to place series resistors between the JTAG lines and
external circuitry so that I can debug the IO pins using JTagICE?