Why _OUTPUT_COMPARE_1_VECTOR interrupr is looping ?

Created Sat, 29 Nov 2014 18:50:37 +0000 by PICedh

PICedh

Sat, 29 Nov 2014 18:50:37 +0000

Hello

As soon as OC1 is enable, the following source loops in the Interrupt fonction and never come back to the main. Could you please indicate what is wrong ?

Here is the log:

vw-setup chipkit prescaler: 1 nticks: 5000 __ISR chipkit end __ISR chipkit __ISR chipkit end __ISR chipkit __ISR chipkit end __ISR chipkit .....

[code]#include <sys/attribs.h> //used for __ISR

extern "C"
{

   
void __ISR(_OUTPUT_COMPARE_1_VECTOR,ipl7) OC1_IntHandler2(void) { //priority 7 
     Serial.println("__ISR chipkit");
     IFS0CLR = 0x0040;// Clear the OC1 interrupt flag}
     Serial.println("end __ISR chipkit");
}


void vw_setup()
{
    uint16_t nticks; // number of prescaled ticks needed
    uint8_t prescaler; // Bit values for CS0[2:0]


    nticks =5000;
    prescaler = 1;
    Serial.println("vw-setup chipkit");
    Serial.print("prescaler: "); Serial.println((int)prescaler);
    Serial.print("nticks: "); Serial.println(nticks);
 
 // Initialization TIMER2
  T2CON = 0x0000 ;  // 0x0000=0000000000000000 
  				    // ON=0 (Timer is disable for now)
                    // FRZ=0 (Continue operation even when CPU is in Debug Exception mode)
                    // SIDL=0 (Continue operation even in Idle mode)
                    // TGATE=0 (Gated time accumulation is disabled) 
                    // TCKPS=000 (prescale value updated below)
                    // T32=0 (TMRx and TMRy form separate 16-bit timer)
                    // TCS=0 (Internal peripheral clock) 
  T2CONbits.TCKPS =  1 << (prescaler-1);   //TCKPS= prescale value CPU clock = 80 MHz => Period : prescale value/80Mhz = prescale value/80 000 000                                              
                                           //111 = 1:256 prescale value
                                           //110 = 1:64 prescale value
                                           //101 = 1:32 prescale value
                                           //100 = 1:16 prescale value
                                           //011 = 1:8 prescale value
                                           //010 = 1:4 prescale value
                                           //001 = 1:2 prescale value
                                           //000 = 1:1 prescale value

  PR2 = nticks;  // TIMER2 Period = (nticks+1)* prescale value/80 000 000  seconds
        
  // Configure the control register OC1CON for the output compare channel 1
  OC1CON = 0x0000; // clear OC1
  OC1CONbits.OCTSEL = 0; // Select Timer 2 as output compare time base
  OC1CONbits.OCM = 0b011; // OCM=011: Compare event toggles OCx pin

  // Configure the compare register OC1R and compare register secondary OC1RS for the output compare channel 1
  OC1R = 5000;  // set initial cycle in counts
  
     
  // Configure int 
  IFS0CLR = 0x0040; // Clear the OC1 interrupt flag 
  IEC0SET = 0x040; // Enable OC1 interrupt 
  IPC1SET = 0x001C0000; // Set OC1 interrupt priority to 7
  IPC1SET = 0x00030000; // Set Subpriority to 3, maximum
   
  // Enable Timer 2 and OC1              
  T2CONSET =  0x8000; // Enable Timer2
  OC1CONSET = 0x8000; // Enable OC1
 
  Serial.println("end vw-setup chipkit");
 

}


void setup()
{
    Serial.begin(9600);	  // Debugging only
    Serial.println("setup");

   vw_setup();	 
}

void loop()
{

    Serial.println("hello");
}

[/code]

}

PICedh

Tue, 02 Dec 2014 21:30:15 +0000

Hi,

Please note that I have removed the 'Serial.println' in the ISR handler and now everything is fine. I don't know the rott casue of the issue but I will take care of the manner to debug ISR