topic Why does the programmer change these bytes in the flash of LPC812 and what do these bytes mean. in LPC Microcontrollers

Why does the programmer change these bytes in the flash of LPC812 and what do these bytes mean.

nkremers — Tue, 03 Jan 2017 14:53:30 GMT

Hi,

Flash a hex-file in-circuit into a LPC812 I use flash magic with an ISP serial interface or i use J-flash with a SWD interface. With these tools we have no problems.

In the production run we use Beeprog2 from elnec. After programming de LPC812 doesn't boot. The same hex-file is used. After programming I see that the flash in the LPC812 is not identical to the data in de .hex-file. Both flash-magic and J-flash change the data in the first row of 64 bytes.

The first 64-bits in the hex file is:

:40000000E80400106901000079010000710100000000000000000000000000000000000000000000000000000000000073010000000000000000000075010000770100000C

The first 64-bits in the flash of the LPC812 is:

:40000000E8040010690100007901000071010000000000000000000000000000C5F6FFEF000000000000000000000000730100000000000000000000750100007701000063

The red part is different and is missing when using the Elnec program tool. I wonder what these bytes mean and why flash magic and j-flash load these files into the flash.

Re: Why does the programmer change these bytes in the flash of LPC812 and what do these bytes mean.

kerryzhou — Wed, 04 Jan 2017 08:43:32 GMT

Hi, N Kremers,

C5F6FFEF is the vector 7 in the NVIC, each vector have 4 bytes, vector 7 is the checksum complement data of vector0 to vector6, just like the following picture:

This checksum complement data normally calculated by the development tools, and write to the chip.

This is why you will find the vector 7 (checksum) data is different as the original data.

If you use Beeprog2 , and can't boot, you can contact with elnec, whether you forget some operation step, we don't have this tool on our side.

Wish it helps you!

Have a great day,
Kerry

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