Forums

Minimum JTAG Connection

Started by Brian C. Lane January 30, 2004
For some reason my original post and Leon's reply didn't make it here. I
see them on the yahoo groups archive though.

So, What is the correct way to get a minimum JTAG setup working with the
secondary JTAG port? Leon's connections are for the primary JTAG port.

Has anyone connected a wiggler to the secondary port with success? I see
that noone has responded to Jim Beagley's post about problems with the
secondary port.

Also, I read on the Philips forum that when using the primary JTAG port
you lose the trace pins even if you aren't using them for trace, right?
This would be a good reason for using the secondary port since I plan to
keep those pins free for jtagging on the production boards.

DBGSEL needs to be pulled high to enable JTAG, but what state should
RTCK be in? The documentation says that it is used to select the second
JTAG port, but doesn't say how to do this.

Thanks,

Brian
--
-----------------
Brian C. Lane (W7BCL) Programmer
www.shinemicro.com RF, DSP & Microcontroller Design




An Engineer's Guide to the LPC2100 Series

Brian,
The experience I have had with the secondary JTAG port has led me to
these conclusions:

A) Put 2 headers on your board, 1 for the Primary, and 1 for the
Secondary connections.
B) The following connections are required:
- 3.3v (i/o voltage)(wiggler may not require)
- TRST
- TDI
- TMS
- TCK
- RTCK
- TDO
- GND
C) Jumper on DBGSEL ( High for Primary, Low for Secondary )
D) PIN 44 pulled high on startup ( if low, debug mode for serial
will be entered)

I am using the NOHAU USB pod, and it requires the 3.3v. It also has a
problem connecting directly to the Secondary port, the following
procedure is required:
- connect using the primary port, switch to secondary, and reset the
debugger. ( this may be unique to NOHAU's SEEHAU debugger )

Also, I have had no success programming with the secondary port. I use
the primary to program, and secondary to debug.

Good luck.

--- In , "Brian C. Lane" <brian@s...> wrote:
> For some reason my original post and Leon's reply didn't make it
here. I
> see them on the yahoo groups archive though.
>
> So, What is the correct way to get a minimum JTAG setup working with
the
> secondary JTAG port? Leon's connections are for the primary JTAG port.
>
> Has anyone connected a wiggler to the secondary port with success? I
see
> that noone has responded to Jim Beagley's post about problems with the
> secondary port.
>
> Also, I read on the Philips forum that when using the primary JTAG port
> you lose the trace pins even if you aren't using them for trace, right?
> This would be a good reason for using the secondary port since I
plan to
> keep those pins free for jtagging on the production boards.
>
> DBGSEL needs to be pulled high to enable JTAG, but what state should
> RTCK be in? The documentation says that it is used to select the second
> JTAG port, but doesn't say how to do this.
>
> Thanks,
>
> Brian >
> --
> -----------------
> Brian C. Lane (W7BCL) Programmer
> www.shinemicro.com RF, DSP & Microcontroller Design





Jim Beagley wrote:

> Brian,
> The experience I have had with the secondary JTAG port has led me to
> these conclusions:
>
> A) Put 2 headers on your board, 1 for the Primary, and 1 for the
> Secondary connections.
> B) The following connections are required:
> - 3.3v (i/o voltage)(wiggler may not require)
> - TRST
> - TDI
> - TMS
> - TCK
> - RTCK
> - TDO
> - GND
> C) Jumper on DBGSEL ( High for Primary, Low for Secondary )
> D) PIN 44 pulled high on startup ( if low, debug mode for serial
> will be entered)
>
> I am using the NOHAU USB pod, and it requires the 3.3v. It also has a
> problem connecting directly to the Secondary port, the following
> procedure is required:
> - connect using the primary port, switch to secondary, and reset the
> debugger. ( this may be unique to NOHAU's SEEHAU debugger )
>
> Also, I have had no success programming with the secondary port. I use
> the primary to program, and secondary to debug.
>
> Good luck.

Thanks for the great info! Having JTAG 2 ports in the design would make
using the 2106 impossible (we really need all those pins). Has anyone
had similar experiences? Or better yet, has anyone successfully used the
second JTAG port for debug and programming?

Also, we are seriously looking at the LPC2124 instead, and it looks like
it only has 1 JTAG port on it, so I'd assume that this wouldn't be a
problem.

Thanks,

Brian
--
-----------------
Brian C. Lane (W7BCL) Programmer
www.shinemicro.com RF, DSP & Microcontroller Design