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ADC interfacing using RTOS on PIC24FJ

Posted by Shashank on April 4, 2013
Hello Everyone!!
I am trying to interface 12, 10 bit-ADC on PIC24FJ256GB210. I successfully ported the RTOS on the same controller and verified it by blinking 2 LEDs in to two task with a delay of 200 ms and 400 ms. The code which I wrote was like this:
void vTask1( void *pvParameters )
{
for( ;; )
{
LATDbits.LATD8 = ~LATDbits.LATD8;
vTaskDelay( 2000 / portTICK_RATE_MS );
}
}
void vTask2( void *pvParameters )
{
for( ;; )
{
LATDbits.LATD9 = ~LATDbits.LATD9;
vTaskDelay( 4000 / portTICK_RATE_MS );
}
}


Then I modified the code of TASK1 to take values of 12 ADCs. The code compiles but doesn't work. The code which I wrote is something like this:
 void vTask_ADC ( void *pvParameters )
{
for( ;; )
{
AD1CON1bits.ASAM = 1;
vAverage_ADC_Readings();
vTaskDelay( 1000 / portTICK_RATE_MS );
}
}


Do I need to write the wrapper class to handle ADC? I have just written the attribute in a C file in which I just set and reset flags.
Thanks in advance.

RE: ADC interfacing using RTOS on PIC24FJ

Posted by Dave on April 4, 2013
I doubt your issue is FreeRTOS related. Try creating a loop in main() to read the ADC before the scheduler is started. Once you have that working it should also work inside your RTOS task as long as it does not do something like leave interrupts disabled.

RE: ADC interfacing using RTOS on PIC24FJ

Posted by Richard Damon on April 4, 2013
I think your biggest issue is that you are going to need to wait for the conversion to be complete before you read it. Since you don't show what vAverage_ADC_Readings() is doing, it is hard to say what is wrong.


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