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PIC18 MCC18 function parameters not working

Posted by Joe Martinosky on April 29, 2008
I am starting to experiment with FreeRTOS on the PIC18f87J11, and have the latest version of it as well as the Microchip tools. I am running into a strange problem where data sent to vTaskDelay doesn't work. I thought I'd write a little LED flasher, but I can't get the delay to work. I have tried passing a variable, defined in the task, as well as directly passing a value. When I debug into the vTaskDelay function, the passed parameter is always 0.


void vLED_task(void *pvParameters);

void main(void)
PORTCbits.RC2 = 1;



void vLED_task()
portTickType xDelayTime = 500;

PORTCbits.RC2 = ~PORTCbits.RC2;

PORTCbits.RC2 = ~PORTCbits.RC2;

I first thought it might be a problem with bank addressing, so I spent a lot of time single-stepping through the assembly code. I understand what the processor is doing, now, but that didn't help me with the problem. I've looked at the post from John Franklin, and implemented it, as well, but to no avail.


RE: PIC18 MCC18 function parameters not working

Posted by Dave on April 29, 2008
Strange, its a simple enough program. Does the demo app for your hardware work ok? Are you sure that the value within vTaskDelay() truly is zero and that its not just an issue with viewing the value within the debugger. I know some debuggers will not show variables that are in registers properly. Are you using optimization?

Sorry, more questions than answers.

RE: PIC18 MCC18 function parameters not working

Posted by Joe Martinosky on April 29, 2008
I'm not using hardware that's compatible with the demo app, so I don't know. I don't believe it's a visibility problem with the debugger because the processing that follows matches what happens if the passed value is zero.

Optimizations are turned off.

My boss has experienced the same problem but attributed it to something else he was doing wrong. He didn't trace it down, though.

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