CRC Question

[dmilrtime]

Hello All,

Using Flashmagic 5.80.22 on a Win 7 Pro 32 bit machine.

My device is an LPC932A1FDH

The issue I am having is I am getting block checksum errors in my application.  On POR my application will calculate the Block Check sums using the supplied sample code.  It compares the calculated CRC with the Stored CRC. 

This has all been working fine until recently.  I have some Micro's that show the problem and some that don't even though they are all using the same hex file.  I have used the CRC check function in Flashmagic and I see that the CRC on the device do not match the calculated CRC of the hex file.  I have attached screen shots to show the discrepancy.

I have tried erasing the chip first (leaving the ISP section alone of course) and the CRC's on the device are 0's as expected.  I searched the forum and understand why Block 7 will always not match.  In fact My CRC Calc function does not check block 7.

Can someone help explain why the device and the hex will not match?  Is it really an error when they don't match?  Is there a good appnote somewhere that explains how these work?

Thanks,
Dave

[Andy Ayre]

In those two screenshots the hex file CRCs are totally different. Is that because the hex file has changed between you grabbing those images?

Does your CRC calculation always match the one generated by Flash Magic? Note that you don't need the microcontroller to test it you can run it as a simple console program. If so then I am not sure what the problem is - perhaps only NXP will know.

Andy

[dmilrtime]

Thanks for the response.  This is definitely a strange issue.

I am not sure where the problem lies, I tried 5 different versions of this application and they all had similar results.  After I loaded them into the micro I would run the CRC check compared to the hex file and they all had issues with matching.

I also tried a few different PCBA's to make sure it was not an isolated micro issue and they all exhibited the same errors. 

The interesting thing to note is my application seems to working just fine.  I just don't very much trust that it will always run fine since a CRC error says there is something wrong with the FLASH and I just may not be seeing it right now.

Dave

[dmilrtime]

Another interesting item to note is that I thought I would play around with the CRC demo supplied with Flash Magic.  When I load the hex file into my micro it also appears to fail the CRC test.

I have attached the screen shot of the CRC check window.

Dave