ARM Technical Support Knowledge Articles

LPC18xx/43xx On-chip Flash Loader Vector Checksum Calculation

Applies to: ARM Development Tools


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When I load an example to the internal flash on the LPC18xx/43xx and correctly set the boot pins, the program still won't run.

What could be wrong?


The most likely reason this happens is that the application does not fulfill the criterion for Valid User Code. Unlike the on-chip flash loaders for other LPC devices, the flash loader for LPC18xx/43xx on-chip flash does not calculate the NXP specific vector table checksum. So the on-chip boot loader will not detect valid user code and does not boot from it.

The reason for this different behavior is that LPC18xx/43xx can boot from different flash banks. It is up to the user to place the vector table in flash bank A or B. The generic flash loader must NOT modify the flash bank which does not contain the vector table.


Add the checksum to the output file with a user command that runs automatically after the build. MDK-ARM also supplies the suitable command line tool for this purpose.

In Options for Target — User — Run User Programs After Build/Rebuild add:


If your application starts from bank A.
Or add:


if your application starts from bank B.
So the correct vector checksum will be added to the output file and the NXP on-chip boot loader will recognize it as valid user code.



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Article last edited on: 2012-09-11 06:28:40

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