Lpc2000

I am using the secondary JTAG on the LPC2106 - its fine. I have done it with a modified Olimex P1 board and my own board

They both use different brands of regulator with no start up sequencing, and a simple RC reset circuit.

Having said that, the secondary JTAG on the first of my boards (3 V up then 1.8 up) spat the dummy and worked intermittanly, then refused to work properly. I built another prototype and that works perfectly.

Not an answer for you - but more information to the digest. 

Hi,

I was wondering if anyone has any information regarding the secondary JTAG -
internal structure. I'm battling a problem that I can only connect to JTAG
after I've SHORTed the 3.3 V line. My powerup sequence is - first core
(1.8v) and then IOs (3.3v) (btw there is nothing in the datasheet that
mentions the sequence, so I presumed it wouldn't matter). Without shorting
the tool will refuse to connect, but once shorted - works like a charm. 

I'm trying to understand the problem behind this. What I'm not sure how is
this presumably muliplexor setup by the core, and how does it stay set after
the core resets. Anyway, I'm out of ideas at this point, but this simple yet
annoying problem is bugging the hell out of me.

Thanks for any insight!

Cheer,

m.