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RE: [lpc2000] Question: Secondary JTAG internals

RE: [lpc2000] Question: Secondary JTAG internals

2004-02-04 by Milos Prokic

Rod, 

Thanks! I will definitely tweak my power circuit to supply 3.3 V first and
then 1.8 keeping the reset low until 1.8 reaches 95%.

Best regards,

Milos
Show quoted textHide quoted text
From: Rod Moffitt [mailto:rodlist@...] 
Sent: Wednesday, February 02, 2005 10:14 PM
To: lpc2000@yahoogroups.com
Subject: Re: [lpc2000] Question: Secondary JTAG internals

 

> Philips has stated, and my experience has been, that there is not a 
> sequencing issue on power up.  I suspect you've got something else going 
> on.  I've not used the secondary JTAG myself, but it does appear to 
> cause people no end of troubles.

I have been using the secondary JTAG on several different LPC2106 designs 
(with different revs of both the chip and boot-loader) since the summer of 
2004 and have not had a single problem.

On a side note. All of the designs had 1.8V regulators that fed off of the 
3.3V mains and only let the LPC2106 out of reset after the 1.8V was in 
spec and then only after a delay in the order of hundreds of milliseconds.

- Rod



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[Non-text portions of this message have been removed]

Question: Secondary JTAG internals

2005-02-02 by Milos Prokic

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.  



[Non-text portions of this message have been removed]

Re: [lpc2000] Question: Secondary JTAG internals

2005-02-02 by Robert Adsett

At 09:16 PM 2/1/05 -0500, Milos Prokic wrote:
>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.


Philips has stated, and my experience has been, that there is not a 
sequencing issue on power up.  I suspect you've got something else going 
on.   I've not used the secondary JTAG myself, but it does appear to cause 
people no end of troubles.

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

RE: [lpc2000] Question: Secondary JTAG internals

2005-02-02 by Milos Prokic

Robert, 

Thanks. The thing is that I built this board myself so I'm guessing that it
is due to my negligence of some kind and not the chip's fault. I tested the
Sec. JTAG prior to this implementation and it seemed to work just fine on
the Ashling LPC dev board. I wasn't gonna clone that board, so I obviously
don't have the same power section. 

How could one explain the fact that shorting 3.3V supply will somehow
kickstart it?.. beats me. I tried all kinds of tricks.. holding the reset,
shorting individual JTAG pins. 

I'll keep poking it in during some off hours :-) 

Cheers,

m.

  

 

  _____
Show quoted textHide quoted text
From: Robert Adsett [mailto:subscriptions@...] 
Sent: Tuesday, February 01, 2005 11:34 PM
To: lpc2000@yahoogroups.com
Subject: Re: [lpc2000] Question: Secondary JTAG internals

 

At 09:16 PM 2/1/05 -0500, Milos Prokic wrote:
>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.


Philips has stated, and my experience has been, that there is not a 
sequencing issue on power up.  I suspect you've got something else going 
on.   I've not used the secondary JTAG myself, but it does appear to cause 
people no end of troubles.

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




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[Non-text portions of this message have been removed]

Question: Secondary JTAG internals

2005-02-02 by Owen Mooney

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.

RE: [lpc2000] Question: Secondary JTAG internals

2005-02-03 by Milos Prokic

Ok. so you're saying that having 3.3V first, than 1.8V works fine now? That
is you did not change anything from the first prototype to second to fix the
JTAG inconsistencies?

Thanks for the info!

Cheers,

m.

 

  _____
Show quoted textHide quoted text
From: Owen Mooney [mailto:ojm@...] 
Sent: Wednesday, February 02, 2005 5:14 PM
To: lpc2000@yahoogroups.com
Subject: [lpc2000] Question: Secondary JTAG internals

 

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.  




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[Non-text portions of this message have been removed]

Re: [lpc2000] Question: Secondary JTAG internals

2005-02-03 by Rod Moffitt

> Philips has stated, and my experience has been, that there is not a 
> sequencing issue on power up.  I suspect you've got something else going 
> on.  I've not used the secondary JTAG myself, but it does appear to 
> cause people no end of troubles.

I have been using the secondary JTAG on several different LPC2106 designs 
(with different revs of both the chip and boot-loader) since the summer of 
2004 and have not had a single problem.

On a side note. All of the designs had 1.8V regulators that fed off of the 
3.3V mains and only let the LPC2106 out of reset after the 1.8V was in 
spec and then only after a delay in the order of hundreds of milliseconds.

- Rod

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