Author Topic: LPC security bits- please clarify  (Read 3178 times)

Roger

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LPC security bits- please clarify
« on: February 04, 2005, 09:56:29 am »
These tssop's (LPC932...936) are soldered in, so they will probably will be destroyed if removed, besides I

Andy Ayre

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Re: LPC security bits- please clarify
« Reply #1 on: February 04, 2005, 10:01:53 am »
You can erase only selected blocks if you wish, simply by selecting them. Any other blocks and their security bits will be ignored.

Don't know about parallel programming, sorry.

If you mean programming CRCs into the device, then no that is not automatic. The LPC9xx family can generate the CRCs and display them when requested (ISP menu -> Cycle Redundancy Check). If you want a checksum that your application can read to verify itself, then you can use the Checksums feature provided in Flash Magic. See the manual for details.

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erikm

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Re: LPC security bits- please clarify
« Reply #2 on: February 04, 2005, 10:41:11 am »
when secured can a parallel programmer be used to read the contents? (not good)

No it cant  Why the "not good?, who cares, the value of retrieved object is infinitessemally small.

Erik

kasd

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Re: LPC security bits- please clarify
« Reply #3 on: September 05, 2005, 01:31:32 am »
Andy,

Now trying to generate the checksum for my LPC931 device using the Flash magic.

However, I have different CRC for my hex file and the LPC931 target after programming.

I choose

1. "Generate checsum" -> checked
2. "Fill unused Flash" -> unchecked
3. "Erase all Flash"-> checked
4. "Protect ISP code"-> checked

There is difference for the 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, the difference CRC for the first four blocks make me very puzzled.

kasd

Andy Ayre

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Re: LPC security bits- please clarify
« Reply #4 on: September 05, 2005, 02:43:17 pm »
If you use the generate checksums option then Flash Magic programs a checksum into the last byte of each block. This will cause the memory contents to be different from the hex file.

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