RE: PEMicro PPCBDM strange behaviour

When you say "as soon as you start the debugger", but presumably the
debug session has already started if reading/writing memory works fine.
Do you really mean 'when you start the CPU running code' ?  This is
relevant and effects the answer.
 
Anyway, if the opcodes are invalid data it could mean a number of
different things and it depends what memory you are using.
 
If you are using external memory, perhaps the chip select or EBI isn't
set correctly.
Perhaps the debugger hasn't loaded your code.
Perhaps there is no memory available where you are trying to locate the
code.
If the code is flash, you have to program it first or instruct the
debugger how to program it.
If the code started running and then stopped, perhaps the CPU has taken
an exception with  no vector and has ended up at an address where you
didn't expect - verify the PC to check this.
After you download the code to memory and set the PC to the start
address, do not run any code, do not run until 'main', etc and see if
your very first instruction is correct.
 
- Allan

________________________________

From: [email protected] [mailto:[email protected]] On Behalf
Of rkaufmanus
Sent: Tuesday, February 06, 2007 2:31 PM
To: [email protected]
Subject: [MPC500] PEMicro PPCBDM strange behaviour



Hi,

I have problems debugging an MPC556 with the PEMicro PPCBDM.
Reading/writing of the ECU memory seems to work fine.

As soon as I start the debugger, I see only nonsense instead of the 
expected program data. The debugger says this nonsense are 'invalid 
opcodes'?!

What is going wrong here?

Thanks + best regards, Rainer



 


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