TIMER1 intterupt of PIC 16f88 in C

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  1. #1
    Join Date
    May 2015

    Default TIMER1 intterupt of PIC 16f88 in C

    I'm trying to work ultrasonic sensor (HCSR-04) with PIC16f88. Since other interrutps (RB0 and INT0) were used I'm trying to operate HCSR04 with Timer1.When I connected trigger and echo to oscillator everyting seems OK. I can see trigger and corresponding echo related with distance. I think interrupt never occurs. When I read data sheet of microcontroller I understand as RB6 is related with TMR1 interrupt. Here is my code.

    #include <xc.h>

    #define _XTAL_FREQ 8000000 // crystal freq defined as 8 Mhz
    int b;

    void main()


    OSCCON = 0b01111000;// 8 Mhz selected Internal Oscillator Freq

    INTCON = 0b11000000; // GIE and PEIE is enabled

    TRISB = 0b01000000;// RB6 selected as input(echo connected here)

    T1CON = 0b01001000; // // System clock is derived from Timer1 oscillator with
    // 1:1 prescale value and oscillator is enabled

    PIE1bits.TMR1IE=1; // tmr1 overflow is enabled

    ei(); // interrupt is enabled



    TMR1H = 0; //Setting Initial Value of Timer
    TMR1L = 0; //Setting Initial Value of Timer
    b = 0; // TM1 value is taken in b (look at interrupt at below)

    __delay_us(10); //trigger is sent
    __delay_ms(100); //Waiting for ECHO

    if(b>2 && b<=20) // If measured distance is between 2-20 cm led
    // at RB1 blinks

    if(b>20 ) // If measured distance is higher than 20 cm led // at RB2 blinks

    } // while closed

    }// main closed

    void interrupt echo()

    if(PIR1bits.TMR1IF == 1) // Code enters if when flag condition occured

    //PIE1bits.TMR1IE=0; // I also tried with that but it didnít work

    T1CONbits.TMR1ON = 1; //Start Timer

    if(RB6 == 0) //If ECHO is LOW
    T1CONbits.TMR1ON = 0; //Stop Timer
    b = (TMR1L | (TMR1H<<8))/58; //Calculate Distance

    PIR1bits.TMR1IF=0; //Clear PORTB On*Change Interrupt flag
    //PIE1bits.TMR1IE=1;// Enable is opened if it is closed at top


  2. #2
    Join Date
    Nov 2003
    Wellton, U.S.A.

    Did you find this post helpful? Yes | No

    Default Re: TIMER1 intterupt of PIC 16f88

    There are a few here that use "C", but the most of us use Pic Basic. I suggest you try over at the MicroChip forums.
    Always wear safety glasses while programming.

  3. #3
    Join Date
    May 2013

    Did you find this post helpful? Yes | No

    Default Re: TIMER1 intterupt of PIC 16f88 in C

    timer1 is not turned on until the interrupt fires therefore it can't trigger an interrupt. the whole concept is flawed
    why no just use portb int on change (its available on a pic16f88 ) portb.rb4:7

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