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When a board just comes off from production lines it is just a bare board without any
data and we usually have to burn the first program to it through the JTAG interface.
However since the S5PV210 supports booting from the TF card the JTAG is not
significant to users any more. Now the JTAG is more often used for debugging. In fact,
most of the widely used utilities in markets like JLINK, ULINK and other simulators
actually work via the JTAG interface. A standard JTAG has 4 signals :TMS, TCK, TDI
and TDO which are test mode select input, test clock, test data input and test data output.
These 4 signal lines plus a power line and a ground line form 6 lines in total. In order for
testing, most simulators even have a reset signal. Therefore, a standard JTAG is supposed
to have those signal lines, and it does not specify whether it is 20Pin or 10Pin. As long as
a JTAG interface has those signal lines it will be a standard JTAG interface. The Mini210
has a 10Pin JTAG interface which has complete standard JTAG signals.
Notes: for beginners who just want to focus on Linux or WinCE development, the JTAG
interface has no significance because most development boards already have a complete
BSP which includes commonly needed serial port, network port and USB port.When a
board runs with Linux or WinCE installed, users can fully utilize more convenient
functions and utilities provided by the operating system to debug. They do not need a
JTAG. Even if you can trace your programs it will be extremely tough to step debug
because it will go into the operating system. This is not an easy job.
