Jon Harris
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 Posted:
Tue Dec 28, 2004 7:00 am Post subject:
SHARC 21065L hardware problem |
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I have one board that has a problem with a 21065L SHARC (many other "identical"
boards work properly). The main symptom I have noticed is that the bus request
line (\BR1) line is always low, even during reset. The board has 2 21065L chips
connected in a standard multi-processor set-up (i.e. shared busses and control
signals). But it appears that DSP ID #1 is driving bus request 1 line low even
during reset. This signal is of course connected to both DSPs, so to isolate
the problem, I lifted the pin from DSP ID #1. The pin still is driven low, so
it seems that the DSP is driving it rather than a short on the board or problem
with the other DSP.
My first assumption is that I have a bad DSP chip. But since it is fairly
difficult and costly to replace the chip, I wanted to see if there was anything
else obvious that might cause this behavior. I checked clock, reset, and chip
ID and they all looked OK. \HBR and \HBG were both high as expected. The boot
mode is set to host boot (\BMS high, BSEL low). Can you think of anything that
would cause the bus request line to be driven low?
Thanks in advance,
Jon |
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