Lpc2000

--- In lpc2000@yahoogroups.com, "Paul Curtis" <plc@r...> wrote:
> John, 
> 
I just
> said in this instance we've proven that the expensive JTAGjet is 
slower
> than a $20 wiggler when downloading and flashing an LPC229x.  I've 
even
> provided numbers to prove it.

You don't seem to be getting the message. We really don't care if one 
device is more optimally used by external software than another for 
downloading to flash. A few seconds here or there every 10 minutes or 
so is not a big issue. Getting information quickly into a debuuger at 
a breakpoint is a big issue.

There is more to the life of developers than downloading to flash and 
there are very important uses for JTAG debuggers when higher speeds 
are a wonderful convenience.

You know a Wiggler or compatible has no buffering capability, is 
clocked under PC software control (via dead simple drivers if W2K or 
XP) and is at the mercy of the operating system and PC hardware.

> 
> > First ETM (Embedded Trace Macrocell) is fitted to all 
> > LPC2xxxx ARM7TDMI-S parts and uses pins independently of JTAG 
> > and so TCK. If LPC2xxxx parts are happy to support ETM 
> > speeds, I don't see why the same parts cannot support very 
> > high JTAG speeds. Why should one set of pins support very 
> > high speeds and not another.
> 
> Try this link.  http://www.arm.com/support/faqip/3732.html.  
Extracting
> the relevent details, "If the RTCK output is not used, it is 
required
> that TCK is running at a maximum of 1/6th the system clock 
frequency if

Suppose RTCK is used then the limitation does not apply.

Suppose the system clock frequency is 60Mhz. Then TCK maximum is 
10Mhz if RTCK output is not taken advantage of. 


> only 1 JTAG synchroniser is implemented in the system."  Although 
the
> ETM will run quickly as it's driven from the core, JTAG will not run
> quickly because without RTCK you can't send data at more than 1/6th 
the
> system clock frequency.  For an LPC2k at 10MHz, that's 1.67MHz TCK.

See above why this is irrelevant to this posting. LPC2xxx parts are 
rated up to 60Mhz and have buffering techniques to minimise wait 
states when executing from flash.

> 
> > I am not an expert on the limiting issues of maximum JTAG TCK 
> > clocking speeds, however I suspect if there are such issues 
> > it is has to do with factors independent of the part, which 
> > may be simply solved. 
> 
> No, you're completely wrong here.  The factors are part of the JTAG
> design on the part, as the above link shows.

No you are wrong. Clearly explained above

 
> Pardon?  The ETM connector does use JTAG signals and they are 
require
> for debugging.  The ETM is for tracing.

ETM pins ON PARTS are not shared with JTAG pins ON PARTS. A single 
Mictor connector may include connections to both set of pins

Tracing is used as a debugging tool.

> > I really don't have time for this.
> 
> Sure you do.  Otherwise you wouldn't have responded.

No I don't have time for this. It brings no benefit to those 
supporting my projects and is not productive. While I recognise those 
who partake in debates can gain noteriety, that is not my business. 


John Heenan