Re: JTAG RTCK / Jeeni question

Started by Michael Johnson October 1, 2005
Hi Tom,

The RTCK isn't strictly needed. Without the RTCK if the JTAG port works
slowly, as is the case of the LPC2xxx, then the JTAG cable/debugger has
to put in a delay before it samples the TDO. I'm surprised that
companies are selling JTAG cables that require RTCK - the cynic in me
says it's a way of getting repeat business.


>--- In lpc2000@lpc2..., Rob Jansen <rob@m...> wrote: >>Does anyone have experience with the Jeeni connected to an lpc2xxx?
>>I got a Jeeni (from EPI) on my desk but heard that it will not connect
>>to the lpc2xxx because of the missing RTCK line on its JTAG interface.
>>I was not yet able to verify this myself yet since I'm still waiting
>for >>the software to arrive (someone misplaced the CDs ...)
>I was informed unequivocally by EPI that the LPC family (and any other
>-S series ARM core) was *not* supported by JEENI specifically due to
>the lack of the RTCK interface. This is what forced me to buy another
>JTAG unit to work with the LPCs, specifically, a BDI2000, since I
>needed to continue to use the GDB server-based interface.
>Abitron also stated that the RTCK support was mandatory, quoting the
>same paragraph from the ARM7DMI-S spec noted in an earlier message.
>If this pin really isn't necessary for correct data timing, then
>Philips needs to get the message out to all the JTAG debugger people.
>-- Tom Nelson >Yahoo! Groups Links

An Engineer's Guide to the LPC2100 Series