Lpc2000

At 10:52 AM 12/17/05 -0500, Tom Walsh wrote:
>Well, you could read the Philips manual for the LPC213x family..  Or,
>you could get an modestly priced evaluation board to try out.   Both
>ways, you will find that you "could" discard JTAG and use those pins for
>I/O.  Realistically, I don't think that you would want to consider doing
>that as how would you develop code???

Wimp :)

It is, of course, quite feasible to develop without using a JTAG.  Indeed 
on some micros with little or nor ICE or on chip debug support it's necessary.

There's a lot to be said for observing the behaviour of the device in 
question and determining from that what must be happening internally.  Add 
a few pins to toggle to indicate code paths and timings and a serial I/O 
port for data dumps and you cover a lot of ground, some of which cannot be 
covered very effectively with JTAG.

Of course there are situations where JTAG or a real ICE is very nearly 
essential.  In fact I'm not yet convinced that JTAG is a complete 
replacement for a proper ICE since I have yet to run into a situation on a 
JTAG equipped micro that demanded the full capabilities of an ICE.

Serial downloads do work quite well and since JTAG takes up so many general 
purpose I/O pins I can see why someone would want to dispense with it, 
especially on the lower pin count devices.  A lot of products really don't 
have room for a 144 pin package especially just to add a debugging interface.

Robert


" 'Freedom' has no meaning of itself.  There are always restrictions,   be 
they legal, genetic, or physical.  If you don't believe me, try to chew a 
radio signal. "  -- Kelvin Throop, III
http://www.aeolusdevelopment.com/