Lpc2000

On Tue, Feb 03, 2004 at 09:01:12AM -0800, Brian C. Lane wrote:
> Leon Heller wrote:
> 
> > ----- Original Message ----- 
> > From: "martin de lange" <martin_de_lange@...>
> > To: <lpc2100@yahoogroups.com>
> > Sent: Tuesday, February 03, 2004 8:23 AM
> > Subject: Re: [lpc2100] JTAG port
> > 
> > 
> > 
> >>Do you mean that one would sometimes use the one JTAG port and at other
> >>times use the other accoording to which I/O you wanted to use ?
> > 
> > 
> > Yes, it's mentioned in the data sheet.
> > 
> > 
> >>I have also seen at times that users at times cannot get the second port
> > 
> > to
> > 
> >>work for debug and or flashing.
> > 
> > 
> > I think that Philips has stated that the second JTAG port cannot be used for
> > programming, only debug.
> > 
> 
> Where? That's a pretty important piece of info. If that's the case then 
> this part isn't as useful as it looks at first glance. If you need the 
> primary JTAG for debug and programming then you lose those pins and the 
> trace pins (from my understanding).
> 
> Sharing JTAG pins with I/O is an understandable practice from the 
> manufacturer's standpoint, but from mine it makes designing things alot 
> more difficult -- its pretty hard to assign any useful function to the 
> pins that are used by the JTAG. You're almost better off programming it 
> via the serial port and using 1-line diagnostics to debug like you have 
> to do on the PIC <G>.

one has to wonder in the days of high density packing why giving
4-5 pins a special function is so abhorent to these manufacturers.

-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.