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DEMO9S12XEP100 flash busy at power on

Question asked by James Murray on Mar 17, 2009
Latest reply on May 9, 2009 by James Murray

I am getting intermittent problems where the flash controller reports it is busy at power on.

FSTAT bit MGBUSY is set and CCIF is clear. (FSTAT = 0x08)

FCLKDIV is set correctly. I changed the crystal to 8MHz, so use value 7.

(I had this issue with the 4MHz crystal too.)


My chip is mask set 1M48H which has an errata relating to flash busy. I believe I followed the published workaround by setting DFPART < 99. I used 98 and disable the EEE in any case.

The problem persists.


The only factor that appears to be repeatable is that I don't believe I have seen this problem when the board is powered from the USB. Mostly I power it from the 12V unreg input and that's when I see this problem.

What's the difference?


I believe that during application development I may have at some point used the wrong FCLKDIV which _may_ have damaged the flash according to the datasheet. But, I would expect to see the problem whatever power supply I was using.


 I'm somewhat stuck here. Not sure what is wrong - my code, the demo board or the CPU?


Any ideas?