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Shut down the memory bus (for a while)



Hi all

We've built a DSP plattform using an Etrax for interfacing. The etrax is
also booting up the Ti DSP via its host port interface, which is directly
connected to the etrax' memory bus. This interface is selectable to be
either 16 or 32 bits wide, which is done with a pull-up or -down resistor on
one of the data pins.

This all works fine when booting the DSP and the Etrax at the same time, but
resetting the DSP during operation is impossible because that very data pin
is apparently driven to the wrong level each time we try. It appears that,
when going through the code to reset the DSP (which is done with a GP pin
connected to the DSPs reset), the same access pattern is sent through the
bus.

Does anyone know how I best bypass this problem? I thought of somehow using
the internal cache and disabling DMA transfers to be sure that the memory
bus is clean for some time....

Thanks a lot
 Bernhard