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P89LPC922 Security bits

Question asked by Rafal Obirek on May 29, 2020
Latest reply on Jul 28, 2020 by Rafal Obirek

Hi everybody,

I have microcontroller LPC922 and he has some sectors locked with security bits ( 0x07 ).

In the documentation is written ( as I understood ) that "global erase" shall clear these bits with 0x00  ( parallel programmer )

http://www.keil.com/dd/docs/datashts/philips/ps_900.pdf 

 

I bought a programmer TOP2013 and during ERASE I have observed with logic analyzer what is written to.

 

As I expected there was written 0x72 order to FMCON register and than is few reads from FMCON to check if programming was successor not.  This checking takes around 4ms  and status is always F0 what tells that chip is BUSY  ( probably erasing is in progress ). But programmer doesn't wait until the status is 0x70 and breaks VCC and return SUCCESS.

Later after reading security bits is still the same and nothing changes.

Writing 0x07 to other sectors which were 0x00 before works perfectly, but restoring it back by global erase not.

 

And my question is now :

1. When security bits for given sector is already 0x07 is it possible to restore it back with 0x00 via global erase at all?

2. How long can take the execution of GLOBAL ERASE for this chip ?

 

Regards

Rafael

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