Lpc2000

--- In lpc2000@yahoogroups.com, "Stephen Pelc" <stephen@m...> wrote:
>
> 
> Warning: Response from JTAG vendor: See
>   http://www.mpeforth.com/jtagwidget.htm
> which is designed for hardwaare bring-up as well as software 
> debugging.
> 
> There are three aspects to consider:
>   connection to PC host
>   connection to ARM target
>   software
> 
> Host Connection
> ===============
> The host connection in rough order of performance and cost is
>   PC parallel port
>   USB
>   dedicated PCI card
> Some parallel port interfaces are powered from the parallel 
> port. Without great care in component selection and PC layout 
> these can be unreliable. We have several, some work well, some 
> don't.
> 
> USB interfaces can draw power from the USB port. In general, 
> these are the most convenient for site use. But the hardware is 
> more expensive and software is required, probably both on the PC 
> and on the JTAG adaptor. Software costs.
> 
> PCI interfaces will give the highest performance, but are 
> usually only found on dedicated testers.
> 
> ARM target connection
> =====================
> As the JTAG speed increases, you need to be more careful with 
> drive levels, cable length and cable impedances. We do not use a 
> cheap HC244, we use a real level shifter on the JTAG side. It's 
> rated to below 1.8 volts. Similarly, the lifetime and cost of a 
> good quality 3M connector is much higher than that of a generic 
> 20 pin connector.
> 
> Software
> ========
> Once you move away from the parallel port connection, you'll 
> most likely have to write software for the adaptor as well as 
> for the PC.
> 
> Conclusion
> ==========
> Better (performance, reliability ...) JTAG debuggers require 
> more work, which has to be paid for somehow or other. Technical 
> support costs time/money too. There's a lot more to ARM JTAG 
> debuggers than at first meets the eye.
> 
> Stephen
> 
> --
> Stephen Pelc, stephen@m...
> MicroProcessor Engineering Ltd - More Real, Less Time
> 133 Hill Lane, Southampton SO15 5AF, England
> tel: +44 23 80 631441, fax: +44 23 80 339691
> web: http://www.mpeforth.com - free VFX Forth downloads
>

Nice analysis, Stephen.

I just wanted to note that you left out my favorite as the most
powerful of the JTAG to workstation connection methods.

 Ethernet!!!!

The Lauterbach Trace32 Ethernet is the fastest and most powerful of
all the JTAG setups that I have used, and extremely expensive.  :-(

One big advantage of Ethernet, is that the workstation and the debug
target do not have to be in the same location. Of course, it is not as
fast over the Internet as it is with a direct local connection.  :-)

Care to give them some competition in that arena?  :-)

-- Dave