Re: jtag debug vs trace

Strictly speaking, trace is a functionality (like breakpoints) that
facilitates debugging. JTAG on the other hand, is an on-chip resource that
allows boundary scan operations to be performed.
This means that 'tracing' can be implemented in multiple ways, one of
which may even use the JTAG infrastructure. In other cases, like you
mentioned, chips may have specialized tracing interfaces devoted to the
operation. So there is fine distinction between the the 'trace' operation
and a special 'trace' interface. The former may be possible without the
latter.
cheers,
-Bhanu

On Wed, 26 Nov 2003, Jee wrote:

> Hi,
>   As a novice I am confused at the difference between JTAG debug and
> trace. As I know JTAG is used for debug, and normally it has 5 pins,
> with background and foreground support, we can run debug software tool
> on host PC to control the embedded processor, this way debug is done.
>   Then comes "trace", on PowerPC it has both JTAG and TRACE interface,
> and I was told TRACE is also used for debugging. Is there any document
> about what TRACE is?
>
> Thanks.
>
>
>