ARM Technical Support Knowledge Articles

USING A BOOTLOADER ON AN AT91SAM7

Applies to: RealView Real-Time Library

Answer


Information in this knowledgebase article applies to:


SYMPTOM

When I use a bootloader to update the application on my AT91SAM7 based system, the application will die with a data abort if I try to run it as soon as the load completes.

CAUSE

On the AT91SAM7, the RTX kernel uses the PIT as the system timer.  The kernel enables the system timer before it initializes its own data. 

If you leave the PIT running during the update, it will trigger an IRQ as soon as you enable it.  This will cause the kernel to attempt to switch tasks, using unititialized data.

RESOLUTION

During your bootloader process, you must disable the PIT and clear any pending interrupts.

ATTACHED FILES

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Article last edited on: 2008-09-09 06:54:06

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