Forums

LPC210x JTAG

Started by Jason May 21, 2011
Hello all, im kind of confused. I have been skimming throught the user manual for the LPC2103 and can only find that to use debug you should Pull-UP RTCK and DBGSEL...

Why in the world does Olimex have so many resistors on the JTAG ?

http://www.olimex.com/dev/images/lpc-h2103-sch.gif

At the top right either something is pulled high or pulled low... are all these needed? or can i get by without them ? and only use the:

RTCK and DBGSEL Pullups ?

An Engineer's Guide to the LPC2100 Series

On 22/05/2011 01:21, Jason wrote:
> Hello all, im kind of confused. I have been skimming throught the user manual for the LPC2103 and can only find that to use debug you should Pull-UP RTCK and DBGSEL...
>
> Why in the world does Olimex have so many resistors on the JTAG ?
>
> http://www.olimex.com/dev/images/lpc-h2103-sch.gif
>
> At the top right either something is pulled high or pulled low... are all these needed? or can i get by without them ? and only use the:
>
> RTCK and DBGSEL Pullups ?

They are recommended by ARM.

I got away with none, when I added JTAG to an LPC2106 board of mine, on
the prototyping area. I couldn't be bothered to add them, and it worked OK.

Leon
--
Leon Heller
G1HSM
Heh Thanks a ton!

I also just remembered that the LPC210x has a bootloader with ISP use so i can omit the JTAG completely on some boards. Since i use the LPC-H2103 Header board from olimex to debug anyway...

...When i make a PCB i can just program it since debugging is complete ... if i need to make changes i can just use header board to test again and then alter code and reprogram via ISP...

Thanks for your help Leon!

Hey i was wondering one more thing... if i dont use the JTAG header at all since i wont be debugging... can i use the P0.27 : P0.31 for GPIO now?

On 22/05/2011 14:30, Jason wrote:
> Heh Thanks a ton!
>
> I also just remembered that the LPC210x has a bootloader with ISP use so i can omit the JTAG completely on some boards. Since i use the LPC-H2103 Header board from olimex to debug anyway...
>
> ...When i make a PCB i can just program it since debugging is complete ... if i need to make changes i can just use header board to test again and then alter code and reprogram via ISP...
>

I used the bootloader initially. However, I had a Wiggler, and wanted to
use that.

Leon
--
Leon Heller
G1HSM
On 22/05/2011 15:07, Jason wrote:
> Hey i was wondering one more thing... if i dont use the JTAG header at all since i wont be debugging... can i use the P0.27 : P0.31 for GPIO now?

That should be OK.

Leon
--
Leon Heller
G1HSM
Thanks a ton Leon! you rock!

--- In l..., Leon Heller wrote:
>
> They are recommended by ARM.
>
> I got away with none, when I added JTAG to an LPC2106 board of mine, on
> the prototyping area. I couldn't be bothered to add them, and it worked OK.

I'm jealous. I have some NewMicros.com 2138 boards (Tini2138 and Pluga2138) and their 2106 board with a built-in 20-pin JTAG (NMIN-2106-USB-1).

The 2138 boards have a 10-pin JTAG and I had to come up with an adapter for my Rowley CrossConnect 20-pin JTAG. *I* had to have all the pullups and pulldowns just to get the Rowley JTAG to work with the boards. Even the 20-pin JTAG on the 2106 had to have an adapter with all of the pullups/pulldowns.

How did you get away without them? What JTAG did you use?

wade

On 23/05/2011 15:05, warm38spl wrote:
> --- In l..., Leon Heller wrote:
>>
>> They are recommended by ARM.
>>
>> I got away with none, when I added JTAG to an LPC2106 board of mine, on
>> the prototyping area. I couldn't be bothered to add them, and it worked OK.
>
> I'm jealous. I have some NewMicros.com 2138 boards (Tini2138 and Pluga2138) and their 2106 board with a built-in 20-pin JTAG (NMIN-2106-USB-1).
>
> The 2138 boards have a 10-pin JTAG and I had to come up with an adapter for my Rowley CrossConnect 20-pin JTAG. *I* had to have all the pullups and pulldowns just to get the Rowley JTAG to work with the boards. Even the 20-pin JTAG on the 2106 had to have an adapter with all of the pullups/pulldowns.
>
> How did you get away without them? What JTAG did you use?

Wiggler.

Leon
--
Leon Heller
G1HSM
I've only used Rowley JTAG, Amontec JTAG, and now I have the Segger J-link (not yet used it).

Wiggler? URL?

--- In l..., Leon Heller wrote:
>
> On 23/05/2011 15:05, warm38spl wrote:
> >
> >
> > --- In l..., Leon Heller wrote:
> >>
> >> They are recommended by ARM.
> >>
> >> I got away with none, when I added JTAG to an LPC2106 board of mine, on
> >> the prototyping area. I couldn't be bothered to add them, and it worked OK.
> >
> > I'm jealous. I have some NewMicros.com 2138 boards (Tini2138 and Pluga2138) and their 2106 board with a built-in 20-pin JTAG (NMIN-2106-USB-1).
> >
> > The 2138 boards have a 10-pin JTAG and I had to come up with an adapter for my Rowley CrossConnect 20-pin JTAG. *I* had to have all the pullups and pulldowns just to get the Rowley JTAG to work with the boards. Even the 20-pin JTAG on the 2106 had to have an adapter with all of the pullups/pulldowns.
> >
> > How did you get away without them? What JTAG did you use?
>
> Wiggler.
>
> Leon
> --
> Leon Heller
> G1HSM
>