Hi,
Can anyone point me to some information on which JTAG lines should
have pull-ups (or pull-downs) and what values for the LPC micros?
I've seen a lot of variations in the schematics of various development
boards - no one seems to do it the same.
The board I am working with has 12k pull-ups on TDI, TCK and nRST, and
a 12k pull-down on RTCK. I'm not sure if this is the best arrangement-
a pull-up on TRST usually seems to be a good idea.
Thanks.
- Charles
LPC2106 JTAG interface pull-up resistors
Started by ●January 24, 2007
Reply by ●January 24, 20072007-01-24
I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k pull-downs on
TCK and RTCK.
It work perect.
On 1/24/07, embeddedkiwi wrote:
>
> Hi,
> Can anyone point me to some information on which JTAG lines should
> have pull-ups (or pull-downs) and what values for the LPC micros?
> I've seen a lot of variations in the schematics of various development
> boards - no one seems to do it the same.
> The board I am working with has 12k pull-ups on TDI, TCK and nRST, and
> a 12k pull-down on RTCK. I'm not sure if this is the best arrangement-
> a pull-up on TRST usually seems to be a good idea.
> Thanks.
>
> - Charles
>
--
N-Link ARM JTAG & ARM7 Boards
--------------
http://www.micro4you.com
http://stores.ebay.com/Micro4you-Store
TCK and RTCK.
It work perect.
On 1/24/07, embeddedkiwi wrote:
>
> Hi,
> Can anyone point me to some information on which JTAG lines should
> have pull-ups (or pull-downs) and what values for the LPC micros?
> I've seen a lot of variations in the schematics of various development
> boards - no one seems to do it the same.
> The board I am working with has 12k pull-ups on TDI, TCK and nRST, and
> a 12k pull-down on RTCK. I'm not sure if this is the best arrangement-
> a pull-up on TRST usually seems to be a good idea.
> Thanks.
>
> - Charles
>
--
N-Link ARM JTAG & ARM7 Boards
--------------
http://www.micro4you.com
http://stores.ebay.com/Micro4you-Store
Reply by ●January 24, 20072007-01-24
somboon sopee wrote:
>
> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k pull-downs on
> TCK and RTCK.
> It work perect.
>
And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
>
> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k pull-downs on
> TCK and RTCK.
> It work perect.
>
And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
Reply by ●January 24, 20072007-01-24
----- Original Message -----
From: "Tom Walsh"
To:
Sent: Wednesday, January 24, 2007 1:05 PM
Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> somboon sopee wrote:
>>
>> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k pull-downs
>> on
>> TCK and RTCK.
>> It work perect.
>>
> And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
> BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
When I added a JTAG connector to my LPC2106 system I didn't know about the
requirement for resistors. It worked OK. 8-)
Leon
--
Leon Heller
Amateur radio call-sign G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
l...@btinternet.com
http://webspace.webring.com/people/jl/leon_heller/
From: "Tom Walsh"
To:
Sent: Wednesday, January 24, 2007 1:05 PM
Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> somboon sopee wrote:
>>
>> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k pull-downs
>> on
>> TCK and RTCK.
>> It work perect.
>>
> And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
> BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
When I added a JTAG connector to my LPC2106 system I didn't know about the
requirement for resistors. It worked OK. 8-)
Leon
--
Leon Heller
Amateur radio call-sign G1HSM
Yaesu FT-817ND transceiver
Suzuki SV1000S motorcycle
l...@btinternet.com
http://webspace.webring.com/people/jl/leon_heller/
Reply by ●January 24, 20072007-01-24
Leon wrote:
>
> ----- Original Message -----
> From: "Tom Walsh" >
> To: >
> Sent: Wednesday, January 24, 2007 1:05 PM
> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>
> > somboon sopee wrote:
> >>
> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
> pull-downs
> >> on
> >> TCK and RTCK.
> >> It work perect.
> >>
> > And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
>
> When I added a JTAG connector to my LPC2106 system I didn't know about
> the
> requirement for resistors. It worked OK. 8-)
>
I think that you would only need the extra resistors (other than RTCK
which the LPC2000 needs) if you use a homebrew wiggler that uses 74xx
logic. If you use a bus driver type of chip that has a good source as
well as sink current, then you wouldn't need the resistors. However, if
you use the wimpy 7414 type logic, that has a weak source current, then
you would probably need the resistors to square off the JTAG signals.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
>
> ----- Original Message -----
> From: "Tom Walsh" >
> To: >
> Sent: Wednesday, January 24, 2007 1:05 PM
> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>
> > somboon sopee wrote:
> >>
> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
> pull-downs
> >> on
> >> TCK and RTCK.
> >> It work perect.
> >>
> > And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
>
> When I added a JTAG connector to my LPC2106 system I didn't know about
> the
> requirement for resistors. It worked OK. 8-)
>
I think that you would only need the extra resistors (other than RTCK
which the LPC2000 needs) if you use a homebrew wiggler that uses 74xx
logic. If you use a bus driver type of chip that has a good source as
well as sink current, then you wouldn't need the resistors. However, if
you use the wimpy 7414 type logic, that has a weak source current, then
you would probably need the resistors to square off the JTAG signals.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
Reply by ●January 24, 20072007-01-24
----- Original Message -----
From: "Tom Walsh"
To:
Sent: Wednesday, January 24, 2007 5:06 PM
Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> Leon wrote:
>>
>> ----- Original Message -----
>> From: "Tom Walsh" >
>> To: >
>> Sent: Wednesday, January 24, 2007 1:05 PM
>> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>>
>> > somboon sopee wrote:
>> >>
>> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
>> pull-downs
>> >> on
>> >> TCK and RTCK.
>> >> It work perect.
>> >>
>> > And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
>> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
>>
>> When I added a JTAG connector to my LPC2106 system I didn't know about
>> the
>> requirement for resistors. It worked OK. 8-)
>> I think that you would only need the extra resistors (other than RTCK
> which the LPC2000 needs) if you use a homebrew wiggler that uses 74xx
> logic. If you use a bus driver type of chip that has a good source as
> well as sink current, then you wouldn't need the resistors. However, if
> you use the wimpy 7414 type logic, that has a weak source current, then
> you would probably need the resistors to square off the JTAG signals.
My Wiggler clone uses a 74HC244.
Leon
From: "Tom Walsh"
To:
Sent: Wednesday, January 24, 2007 5:06 PM
Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> Leon wrote:
>>
>> ----- Original Message -----
>> From: "Tom Walsh" >
>> To: >
>> Sent: Wednesday, January 24, 2007 1:05 PM
>> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>>
>> > somboon sopee wrote:
>> >>
>> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
>> pull-downs
>> >> on
>> >> TCK and RTCK.
>> >> It work perect.
>> >>
>> > And, I only use a 10K pulldown on RTCK. This works fine for an Abatron
>> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've built.
>>
>> When I added a JTAG connector to my LPC2106 system I didn't know about
>> the
>> requirement for resistors. It worked OK. 8-)
>> I think that you would only need the extra resistors (other than RTCK
> which the LPC2000 needs) if you use a homebrew wiggler that uses 74xx
> logic. If you use a bus driver type of chip that has a good source as
> well as sink current, then you wouldn't need the resistors. However, if
> you use the wimpy 7414 type logic, that has a weak source current, then
> you would probably need the resistors to square off the JTAG signals.
My Wiggler clone uses a 74HC244.
Leon
Reply by ●January 25, 20072007-01-25
Leon wrote:
>
> ----- Original Message -----
> From: "Tom Walsh" >
> To: >
> Sent: Wednesday, January 24, 2007 5:06 PM
> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>
> > Leon wrote:
> >>
> >> ----- Original Message -----
> >> From: "Tom Walsh" > 40openhardware. net>>
> >> To: >
> >> Sent: Wednesday, January 24, 2007 1:05 PM
> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> >>
> >> > somboon sopee wrote:
> >> >>
> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
> >> pull-downs
> >> >> on
> >> >> TCK and RTCK.
> >> >> It work perect.
> >> >>
> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
> Abatron
> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
> built.
> >>
> >> When I added a JTAG connector to my LPC2106 system I didn't know about
> >> the
> >> requirement for resistors. It worked OK. 8-)
> >>
> >
> > I think that you would only need the extra resistors (other than RTCK
> > which the LPC2000 needs) if you use a homebrew wiggler that uses 74xx
> > logic. If you use a bus driver type of chip that has a good source as
> > well as sink current, then you wouldn't need the resistors. However, if
> > you use the wimpy 7414 type logic, that has a weak source current, then
> > you would probably need the resistors to square off the JTAG signals.
>
> My Wiggler clone uses a 74HC244.
>
That should be good. I've seen some wiggler designs where they used
7404 / 7414 devices. I would imagine that you would need to use pullups
with those to get any real speed.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
>
> ----- Original Message -----
> From: "Tom Walsh" >
> To: >
> Sent: Wednesday, January 24, 2007 5:06 PM
> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>
> > Leon wrote:
> >>
> >> ----- Original Message -----
> >> From: "Tom Walsh" > 40openhardware. net>>
> >> To: >
> >> Sent: Wednesday, January 24, 2007 1:05 PM
> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> >>
> >> > somboon sopee wrote:
> >> >>
> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
> >> pull-downs
> >> >> on
> >> >> TCK and RTCK.
> >> >> It work perect.
> >> >>
> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
> Abatron
> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
> built.
> >>
> >> When I added a JTAG connector to my LPC2106 system I didn't know about
> >> the
> >> requirement for resistors. It worked OK. 8-)
> >>
> >
> > I think that you would only need the extra resistors (other than RTCK
> > which the LPC2000 needs) if you use a homebrew wiggler that uses 74xx
> > logic. If you use a bus driver type of chip that has a good source as
> > well as sink current, then you wouldn't need the resistors. However, if
> > you use the wimpy 7414 type logic, that has a weak source current, then
> > you would probably need the resistors to square off the JTAG signals.
>
> My Wiggler clone uses a 74HC244.
>
That should be good. I've seen some wiggler designs where they used
7404 / 7414 devices. I would imagine that you would need to use pullups
with those to get any real speed.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
Reply by ●January 26, 20072007-01-26
On Thu, 25 Jan 2007 13:11:20 -0500, you wrote:
>Leon wrote:
>>
>> ----- Original Message -----
>> From: "Tom Walsh" >
>> To: >
>> Sent: Wednesday, January 24, 2007 5:06 PM
>> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>>
>> > Leon wrote:
>> >>
>> >> ----- Original Message -----
>> >> From: "Tom Walsh" >> 40openhardware. net>>
>> >> To: >
>> >> Sent: Wednesday, January 24, 2007 1:05 PM
>> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>> >>
>> >> > somboon sopee wrote:
>> >> >>
>> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
>> >> pull-downs
>> >> >> on
>> >> >> TCK and RTCK.
>> >> >> It work perect.
>> >> >>
>> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
>> Abatron
>> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
>> built.
>> >>
>> >> When I added a JTAG connector to my LPC2106 system I didn't know about
>> >> the
>> >> requirement for resistors. It worked OK. 8-)
>> >>
>> >
>> > I think that you would only need the extra resistors (other than RTCK
>> > which the LPC2000 needs)
According to the datasheet (2103 & 2106)
"RTCK : Returned Test Clock output: Extra signal added to the JTAG port. Assists
debugger synchronization when processor frequency varies. Also used during
debug mode entry to select primary or secondary JTAG pins with the 48-pin
package. Bidirectional pin with internal pull-up."
Am I missing something here - why do you say RTCK needs a resistor?
J-link doesn't even use this pin - don't know about any other Jtag interfaces
>Leon wrote:
>>
>> ----- Original Message -----
>> From: "Tom Walsh" >
>> To: >
>> Sent: Wednesday, January 24, 2007 5:06 PM
>> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>>
>> > Leon wrote:
>> >>
>> >> ----- Original Message -----
>> >> From: "Tom Walsh" >> 40openhardware. net>>
>> >> To: >
>> >> Sent: Wednesday, January 24, 2007 1:05 PM
>> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>> >>
>> >> > somboon sopee wrote:
>> >> >>
>> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
>> >> pull-downs
>> >> >> on
>> >> >> TCK and RTCK.
>> >> >> It work perect.
>> >> >>
>> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
>> Abatron
>> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
>> built.
>> >>
>> >> When I added a JTAG connector to my LPC2106 system I didn't know about
>> >> the
>> >> requirement for resistors. It worked OK. 8-)
>> >>
>> >
>> > I think that you would only need the extra resistors (other than RTCK
>> > which the LPC2000 needs)
According to the datasheet (2103 & 2106)
"RTCK : Returned Test Clock output: Extra signal added to the JTAG port. Assists
debugger synchronization when processor frequency varies. Also used during
debug mode entry to select primary or secondary JTAG pins with the 48-pin
package. Bidirectional pin with internal pull-up."
Am I missing something here - why do you say RTCK needs a resistor?
J-link doesn't even use this pin - don't know about any other Jtag interfaces
Reply by ●January 29, 20072007-01-29
Mike Harrison wrote:
>
> On Thu, 25 Jan 2007 13:11:20 -0500, you wrote:
>
> >Leon wrote:
> >>
> >> ----- Original Message -----
> >> From: "Tom Walsh" > 40openhardware. net>>
> >> To: >
> >> Sent: Wednesday, January 24, 2007 5:06 PM
> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> >>
> >> > Leon wrote:
> >> >>
> >> >> ----- Original Message -----
> >> >> From: "Tom Walsh" > >> 40openhardware. net>>
> >> >> To: >
> >> >> Sent: Wednesday, January 24, 2007 1:05 PM
> >> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> >> >>
> >> >> > somboon sopee wrote:
> >> >> >>
> >> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
> >> >> pull-downs
> >> >> >> on
> >> >> >> TCK and RTCK.
> >> >> >> It work perect.
> >> >> >>
> >> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
> >> Abatron
> >> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
> >> built.
> >> >>
> >> >> When I added a JTAG connector to my LPC2106 system I didn't know
> about
> >> >> the
> >> >> requirement for resistors. It worked OK. 8-)
> >> >>
> >> >
> >> > I think that you would only need the extra resistors (other than RTCK
> >> > which the LPC2000 needs)
>
> According to the datasheet (2103 & 2106)
>
> "RTCK : Returned Test Clock output: Extra signal added to the JTAG
> port. Assists
> debugger synchronization when processor frequency varies. Also used during
> debug mode entry to select primary or secondary JTAG pins with the 48-pin
> package. Bidirectional pin with internal pull-up."
>
> Am I missing something here - why do you say RTCK needs a resistor?
> J-link doesn't even use this pin - don't know about any other Jtag
> interfaces
>
Dig a little deeper into the manual. Technically it doesn't need one if
you are using P1.26 to P1.30 as GPIO when the board boots normally.
However, if you want the JTAG interface enabled, you have to have the
pin held at a logic Low.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
>
> On Thu, 25 Jan 2007 13:11:20 -0500, you wrote:
>
> >Leon wrote:
> >>
> >> ----- Original Message -----
> >> From: "Tom Walsh" > 40openhardware. net>>
> >> To: >
> >> Sent: Wednesday, January 24, 2007 5:06 PM
> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> >>
> >> > Leon wrote:
> >> >>
> >> >> ----- Original Message -----
> >> >> From: "Tom Walsh" > >> 40openhardware. net>>
> >> >> To: >
> >> >> Sent: Wednesday, January 24, 2007 1:05 PM
> >> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
> >> >>
> >> >> > somboon sopee wrote:
> >> >> >>
> >> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
> >> >> pull-downs
> >> >> >> on
> >> >> >> TCK and RTCK.
> >> >> >> It work perect.
> >> >> >>
> >> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
> >> Abatron
> >> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
> >> built.
> >> >>
> >> >> When I added a JTAG connector to my LPC2106 system I didn't know
> about
> >> >> the
> >> >> requirement for resistors. It worked OK. 8-)
> >> >>
> >> >
> >> > I think that you would only need the extra resistors (other than RTCK
> >> > which the LPC2000 needs)
>
> According to the datasheet (2103 & 2106)
>
> "RTCK : Returned Test Clock output: Extra signal added to the JTAG
> port. Assists
> debugger synchronization when processor frequency varies. Also used during
> debug mode entry to select primary or secondary JTAG pins with the 48-pin
> package. Bidirectional pin with internal pull-up."
>
> Am I missing something here - why do you say RTCK needs a resistor?
> J-link doesn't even use this pin - don't know about any other Jtag
> interfaces
>
Dig a little deeper into the manual. Technically it doesn't need one if
you are using P1.26 to P1.30 as GPIO when the board boots normally.
However, if you want the JTAG interface enabled, you have to have the
pin held at a logic Low.
TomW
--
Tom Walsh - WN3L - Embedded Systems Consultant
http://openhardware.net http://cyberiansoftware.com http://openzipit.org
"Windows? No thanks, I have work to do..."
----------------
Reply by ●January 29, 20072007-01-29
On Fri, 26 Jan 2007 08:08:12 -0500, you wrote:
>Mike Harrison wrote:
>>
>> On Thu, 25 Jan 2007 13:11:20 -0500, you wrote:
>>
>> >Leon wrote:
>> >>
>> >> ----- Original Message -----
>> >> From: "Tom Walsh" >> 40openhardware. net>>
>> >> To: >
>> >> Sent: Wednesday, January 24, 2007 5:06 PM
>> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>> >>
>> >> > Leon wrote:
>> >> >>
>> >> >> ----- Original Message -----
>> >> >> From: "Tom Walsh" >> >> 40openhardware. net>>
>> >> >> To: >
>> >> >> Sent: Wednesday, January 24, 2007 1:05 PM
>> >> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>> >> >>
>> >> >> > somboon sopee wrote:
>> >> >> >>
>> >> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
>> >> >> pull-downs
>> >> >> >> on
>> >> >> >> TCK and RTCK.
>> >> >> >> It work perect.
>> >> >> >>
>> >> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
>> >> Abatron
>> >> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
>> >> built.
>> >> >>
>> >> >> When I added a JTAG connector to my LPC2106 system I didn't know
>> about
>> >> >> the
>> >> >> requirement for resistors. It worked OK. 8-)
>> >> >>
>> >> >
>> >> > I think that you would only need the extra resistors (other than RTCK
>> >> > which the LPC2000 needs)
>>
>> According to the datasheet (2103 & 2106)
>>
>> "RTCK : Returned Test Clock output: Extra signal added to the JTAG
>> port. Assists
>> debugger synchronization when processor frequency varies. Also used during
>> debug mode entry to select primary or secondary JTAG pins with the 48-pin
>> package. Bidirectional pin with internal pull-up."
>>
>> Am I missing something here - why do you say RTCK needs a resistor?
>> J-link doesn't even use this pin - don't know about any other Jtag
>> interfaces
>>
>Dig a little deeper into the manual. Technically it doesn't need one if
>you are using P1.26 to P1.30 as GPIO when the board boots normally.
>However, if you want the JTAG interface enabled, you have to have the
>pin held at a logic Low.
OK - re-reading the manual, as I understand it, you only need to connect RTCK if using JTAG for
things OTHER than debugging, i.e. boundary scan for testing etc.
Otherwise the internal pullup will make the pins work as GPIO when DBGSEL is low, or as JTAG debug
when DBGSEL is high.
>Mike Harrison wrote:
>>
>> On Thu, 25 Jan 2007 13:11:20 -0500, you wrote:
>>
>> >Leon wrote:
>> >>
>> >> ----- Original Message -----
>> >> From: "Tom Walsh" >> 40openhardware. net>>
>> >> To: >
>> >> Sent: Wednesday, January 24, 2007 5:06 PM
>> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>> >>
>> >> > Leon wrote:
>> >> >>
>> >> >> ----- Original Message -----
>> >> >> From: "Tom Walsh" >> >> 40openhardware. net>>
>> >> >> To: >
>> >> >> Sent: Wednesday, January 24, 2007 1:05 PM
>> >> >> Subject: Re: [lpc2000] LPC2106 JTAG interface pull-up resistors
>> >> >>
>> >> >> > somboon sopee wrote:
>> >> >> >>
>> >> >> >> I used 10k pull-ups on TRST, TDI, TMS and TDO , and used 10k
>> >> >> pull-downs
>> >> >> >> on
>> >> >> >> TCK and RTCK.
>> >> >> >> It work perect.
>> >> >> >>
>> >> >> > And, I only use a 10K pulldown on RTCK. This works fine for an
>> >> Abatron
>> >> >> > BDI2000 with the LPC2106, LPC2138, and LPC2214 designs that I've
>> >> built.
>> >> >>
>> >> >> When I added a JTAG connector to my LPC2106 system I didn't know
>> about
>> >> >> the
>> >> >> requirement for resistors. It worked OK. 8-)
>> >> >>
>> >> >
>> >> > I think that you would only need the extra resistors (other than RTCK
>> >> > which the LPC2000 needs)
>>
>> According to the datasheet (2103 & 2106)
>>
>> "RTCK : Returned Test Clock output: Extra signal added to the JTAG
>> port. Assists
>> debugger synchronization when processor frequency varies. Also used during
>> debug mode entry to select primary or secondary JTAG pins with the 48-pin
>> package. Bidirectional pin with internal pull-up."
>>
>> Am I missing something here - why do you say RTCK needs a resistor?
>> J-link doesn't even use this pin - don't know about any other Jtag
>> interfaces
>>
>Dig a little deeper into the manual. Technically it doesn't need one if
>you are using P1.26 to P1.30 as GPIO when the board boots normally.
>However, if you want the JTAG interface enabled, you have to have the
>pin held at a logic Low.
OK - re-reading the manual, as I understand it, you only need to connect RTCK if using JTAG for
things OTHER than debugging, i.e. boundary scan for testing etc.
Otherwise the internal pullup will make the pins work as GPIO when DBGSEL is low, or as JTAG debug
when DBGSEL is high.
