68HC11

[Steve Ravet]

Close.  I hadn't heard of the Buffalo monitor so I searched for it on
the WWW.  Buffalo what's called a monitor.  It's some code that is in
the system who's only purpose is to communicate with an external
debugger.  It communicates to a PC or something over a serial port.  If
the user wants to see the value stored in the register, the PC sends a
request over the serial port, which interrupts whatever the
microcontroller was doing, jumps to the monitor, and sends the requested
info to the PC which displays it for the user.  The monitor program has
to be in memory along with the engine control code, which is not
desirable.  Takes up code space.

BDM is all hardware on the microcontroller end.  The BDM port literally
pokes around the inards of the microcontroller to find out what it needs
to know.  That way there is no impact on the engine controller code.

Both have the same purpose, to allow debugging of embedded hardware
without actually having a display, keyboard, etc. on the embedded
system.

--steve

Shannen Durphey wrote:
> 
> steve ravet wrote:
> 
> >
> > BDM means "background debugging mode".  It's a few pins on the processor
> > that allow you to do debugging from outside the chip.  From the BDM port
> > you can halt the CPU, read/write the registers, read/write any memory in
> > the system, set breakpoints in the code, etc. etc. etc.  Lots of
> > processors have them, they're all the same idea but none are compatible
> > with each other.
> >
> > Usually there's an interface board that connects between the processor
> > and a PC, and some debugging software on the PC that lets you see what's
> > going on.
> >
> > --steve
> Is this what the Buffalo monitor is for?
> Shannen

--
Steve Ravet
sravet at arm.com
Advanced Risc Machines, INC
www.arm.com