ARM Cortex-M3 Jtag question

[muzzamil8]

Hi,

I am using LM3S6965 microcontroller which uses JTAG standard for programming. It is an ARM core and uses standard 20-pin connector for programming the controller. My question is, can I use 20-pin to 6-pin cable with 20-pin connector on external debugger (JLINK) and 6-pin connector on target board? 6 pins on target board will include signals TDI,TDO,TMS,TCK,GND,VCC. Is it correct design?

Secondly, What is the purpose of 9 ground pins (4,6,8,10,12,14,16,18,20 pins) on standard 20-pin JTAG connector?

 

[cionst]

Yes, you can use 6PINS. But normally I use TDI,TDO,TMS,TCK,TRST,RTCK,GND,VCC.

 

[FvM]

Some debug/trace adapters are relying on the RTCK signal to achieve higher speed. You should check with your tools.

 

[muzzamil8]

What is the purpose of RTCK signal?