porting FreeRtos to atmega2560

Jul 23, 2008 1 Replies

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Hello All. I try to port FreRtos to atmega2560 WinAVR I modified this piece in port.c

usAddress = ( unsigned portSHORT ) pxCode;

*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); pxTopOfStack--;

usAddress >>= 8;

*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); pxTopOfStack--;

/* AND THE THIRD BYTE */ usAddress >>= 8;

*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); pxTopOfStack--; /* end of AND THE THIRD BYTE */

and changed timer interrupt settings to make interrupt work. But still it resets even if I have only Idle Hook Task with only one vTaskDelay function inside. Could somebody point what I had overlooked? Thanks Alex.

Hello, I've had the same problem and after reading your post and ATMega2560's datasheet I changed pxPortInitializeStack() in port.c as follow:

usAddress = ( unsigned portLONG ) pxCode; *pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portLONG ) 0x000000ff ); pxTopOfStack--;

usAddress >>= 8; *pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portLONG ) 0x000000ff ); pxTopOfStack--;

and I redifined type of usAddress variable as well: unsigned portLONG usAddress; because portSHORT in AVR is only 16-bit wide and ATMega2560 have 22- bit Program Counter register. After these changes I port FreeRTOS demo to ATMega2560 and it works correctly.

Good Luck, walert

porting FreeRtos to atmega2560

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