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AT91 Port ram usage

Posted by johanan on January 8, 2005
I just started with this AT91 and compiled the demo port. It usese about 14K of RAM, which is quit a lot for a 16K device - can you explain how to reduce this and what is taking most of the RAM?

RE: AT91 Port ram usage

Posted by Richard on January 8, 2005
The demo application creates a lot of tasks (22?), most of which are tasks that are common to a number of different ports. Each task requires its own stack, which takes up memory. The demo application is sized for the amount of RAM available (that is, I made it create as many tasks as would fit with a little bit spare).

There is a block of memory allocated to the kernel. This is basically a large array from which the kernel can obtain memory as needed. In the case of the AT91 demo no memory is dynamically allocated other than that allocated by the kernel – so the block of memory made available to the kernel is sized to nearly fill the entire RAM available. The size of this memory block can be made smaller or larger as required.

Depending on how your application uses memory you may wish to leave the memory block taking up nearly the entire RAM space and then use the pvPortMalloc() and vPortFree() functions from your application is necessary. Or, you may wish to make the memory block just big enough for the kernel needs.





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