Author Topic: CRC for LPC931  (Read 2723 times)

kasd

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CRC for LPC931
« on: September 05, 2005, 02:01:08 am »
Now trying to generate the checksum for my LPC931 device using the Flash magic. I would like to verify if this is the correct method.

If I choose these option
1. "Generate checksum" -> unchecked
2. "Fill unused Flash" -> unchecked
3. "Erase all Flash"-> checked
4. "Protect ISP code"-> checked
5. All "block x security bits" -> unchecked.

The CRC read from the DEVICE and that of the hex file will be same for memory block 0, 1, 2, and 3 that my code used. The total checksum will be different as expected since my code does not include the ISP code.

However, if I were to choose other options specifically checking the "Filled unused Flash", the CRC will be different from the hex file for the first four memory blocks.

The puzzling thing is that "Filled unused Flash" is using 0x00 so should be ok, unless empty Flash is usually filled with'0xff?

Anyone any idea?

Andy Ayre

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Re: CRC for LPC931
« Reply #1 on: September 05, 2005, 02:44:22 pm »
Please don't post your question twice!

As I posted in response to your question in the other thread, using the generate checksums option will alter the contents of flash memory so it doesn't match the hex file any more. The generate checksums feature is fully described in the manual.

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kasd

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Re: CRC for LPC931
« Reply #2 on: September 05, 2005, 10:43:51 pm »
Thanks for replying.

Sorry about doubel posting. I did not manage to find the previous post so I posted again.