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Using FreeRTOS from Scratch.

Posted by erik on May 24, 2007
Hi,

I've been trying to use the FreeRTOS from scratch. I'm using IAR EWARM for the ARM LPC2129. I've gotten the demo to work and I have read through the API thoroughly. I believe I've included the bulk of the files necessary to compile, since I can compile. The issue that I come to is when I'm trying to create a task it seems to freeze the entire system and an interrupt goes off. The following is what I'm doing.


StarttestMath();
vTaskStartScheduler();


void StarttestMath(void)
{
xTaskHandle TestHandle;
xTaskCreate(TestMath , "Test", 4, 0, 3, &TestHandle);
}

I am not using the originaly Cstartup.79

Can someone help me?
Thanks,
Erik


RE: Using FreeRTOS from Scratch.

Posted by embeddedc on May 25, 2007
Is it a peripheral interrupt or an abort that is causing the problem?

If it is a peripheral interrupt then make sure you don't allow any interrupts to execute that use the FreeRTOS API prior to the scheduler being started.

The most likely cause is something in the startup file. The startup file must:

i/ Call main() in Supervisor mode (or at least you must switch to supervisor mode prior to starting the scheduler).
ii/ Setup stacks for Supervisor and IRQ mode. FIQ mode too if FIQs are being used. You need not setup stacks for user mode as the kernel does this for you.
iii/ Setup the VIC to vector directly to interrupts with not code in between.

The best thing to do is not start from scratch but modify one of the demos provided for you.


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