How to detect JTAG is connected or not

thanks for the answers , I am a software guy, I went thru the docs but
could not find a answers, I am using Au1550 processor and DM642.

For completeness, host board circuitry is required to maintain the JTAG
port lines, although chip manufacturers may provide internal pull-ups /
downs.

For devices with TRST ( I know it's active low, but that's it's name in
the spec :) pull all other lines high, pull TRST low. (There are
exceptions to this - the Intel PXA series has specific *ordinary* reset
timing requirements applied to TRST).

For devices that do not have TRST:

Pull TCK ***LOW***, TDI, TMS high. The reason is the JTAG chain will
enter test mode with TMS high on a rising edge of TCK. At system
startup, depending on the board capacitances and the resistor sizes (to
say nothing of chip innards), if both TCK and TMS are pulled to power,
it is possible that normal startup can put the device in test mode (not
a good thing [tm]).

Cheers

PeteS