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Work with functions on PIC16F76

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nexus_1975

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I am using PIC16F76 I am trying to write my own code.

When I use the following code it compiles and runs on hardware with 1 error.
If RC4_bit == 0 and i == 10 program will work well since 2nd iteration, i want it work with 1st iteration.
ChecFunc( ) not working during 1st iteration!
Code C - [expand]
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/*
 * Test configuration:
     MCU:             PIC16F76
 */
 
unsigned int i, count, cnt, time_in_ms;
void Vdelay_ms(time_in_ms);
CheckFunc(time_in_ms);
 
CheckFunc(time_in_ms)
       {
        if((RC4_bit == 0) && (i == 10)) //continue;
                    {
                    i=0;
                    PORTA = 0x00;
                    time_in_ms = 150;//continue;
                    }
                    else if((RC3_bit == 0) && (i == 20)) //continue;
                         {
                         i=0;
                         PORTA = 0x00;
                         time_in_ms = 150;//continue;
                         }
                         else if(RC2_bit == 0)
                               {
                               time_in_ms = 120; //continue;
                               }
                               else if(RC1_bit == 0)
                                    {
                                    time_in_ms = 200;//continue;
                                    }
                                    else if(RC0_bit == 0)
                                         {
                                         time_in_ms = 1000; //continue;
                                         }
                                               else if(PORTC == 0xFF)
                                               {
                                               time_in_ms = 500; //continue;
                                               }
         return time_in_ms;
        }
 
void main()
{
//
// initialize system
//
        ADCON0 = 0;
        ADCON1 = 0x07;               // all digital port pins
        TRISC = 0xFF;                // port C, bit 1, is input
        TRISB = 0x00;                // port B, bit 0, is output
        TRISA = 0x00;                // port A is output
        PORTC = 0xFF;
        PORTB = 0x00;                // all LEDs on
        PORTA = 0x00;
        cnt = 0;             // Initialize cnt
        INTCON = 0x00;       // Set GIE, PEIE
        time_in_ms = 150;            // start count at zero
 
        while ( 1 )                // the one and only program loop
        {
        for(count=0;count<=7;count++)
        {
 
               PORTB = 0x10;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x01;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x02;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x04;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x08;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
 
               PORTA = PORTA++;         //
               i=i+5;
 
        }
        PORTA = 0x00;
        PORTB = 0x00;
        count=0;
        i=0;
        }
}
Added code tags
 
Last edited by a moderator:
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You are talking about "error" in code behaviour but don't tell what expected versus observed behaviour is.

My first observation, you are calling CheckFunc() without actual argument. I expect that inside CheckFunc() time_in_ms is treated as local variable, it's never read anywhere in the code, neither inside the function nor as return value.

Calling a function without defined arguments would be normally flagged as error unless the argument has a default value (an option provided by some compilers).
 
Upvote 0 Downvote
Hi,

What´s the idea of:
increasing "i" by 5
then check against 10 and 20

isn´t it the same as
increasing "i" by 1
and checking it against 2 and 4

****
I don´t recommend to make "i" as a public/global variable at all
The better way is to make it local to main() and pass it to the fucntion via a pointer.
But indeed the even better way is to not modify "i" in the fucntion at all. You could use a rrtutn value of the funtion... to modify "i" in main() only. This way "i" is not used in the function at all.

***

As far as I can see ... CheckFunc leaves a lot of "unchecked" conditions.

Klaus
 
Upvote 0 Downvote
nexus_1975 said:
I am using PIC16F76 I am trying to write my own code.

When I use the following code it compiles and runs on hardware with 1 error.
If RC4_bit == 0 and i == 10 program will work well since 2nd iteration, i want it work with 1st iteration.
ChecFunc( ) not working during 1st iteration!
Code C - [expand]
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/*
 * Test configuration:
     MCU:             PIC16F76
 */
 
unsigned int i, count, cnt, time_in_ms;
void Vdelay_ms(time_in_ms);
CheckFunc(time_in_ms);
 
CheckFunc(time_in_ms)
       {
        if((RC4_bit == 0) && (i == 10)) //continue;
                    {
                    i=0;
                    PORTA = 0x00;
                    time_in_ms = 150;//continue;
                    }
                    else if((RC3_bit == 0) && (i == 20)) //continue;
                         {
                         i=0;
                         PORTA = 0x00;
                         time_in_ms = 150;//continue;
                         }
                         else if(RC2_bit == 0)
                               {
                               time_in_ms = 120; //continue;
                               }
                               else if(RC1_bit == 0)
                                    {
                                    time_in_ms = 200;//continue;
                                    }
                                    else if(RC0_bit == 0)
                                         {
                                         time_in_ms = 1000; //continue;
                                         }
                                               else if(PORTC == 0xFF)
                                               {
                                               time_in_ms = 500; //continue;
                                               }
         return time_in_ms;
        }
 
void main()
{
//
// initialize system
//
        ADCON0 = 0;
        ADCON1 = 0x07;               // all digital port pins
        TRISC = 0xFF;                // port C, bit 1, is input
        TRISB = 0x00;                // port B, bit 0, is output
        TRISA = 0x00;                // port A is output
        PORTC = 0xFF;
        PORTB = 0x00;                // all LEDs on
        PORTA = 0x00;
        cnt = 0;             // Initialize cnt
        INTCON = 0x00;       // Set GIE, PEIE
        time_in_ms = 150;            // start count at zero
 
        while ( 1 )                // the one and only program loop
        {
        for(count=0;count<=7;count++)
        {
 
               PORTB = 0x10;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x01;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x02;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x04;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
               PORTB = 0x08;
               CheckFunc();
               Vdelay_ms(time_in_ms);  /* One second pause */
 
               PORTA = PORTA++;         //
               i=i+5;
 
        }
        PORTA = 0x00;
        PORTB = 0x00;
        count=0;
        i=0;
        }
}
Added code tags
Click to expand...
To ensure CheckFunc() behaves as expected from the first iteration, there are a few modifications and improvements that can be made to your code:

  1. Function Prototypes: Define function prototypes for Vdelay_ms() and CheckFunc() at the beginning to ensure proper recognition by the compiler.
  2. Parameter Handling: CheckFunc is designed to take a parameter time_in_ms, but in main() it’s called without arguments, causing a mismatch.
  3. Initialization: Ensure i is properly initialized at the start of the main loop, so it correctly counts from the beginning.
C: 
/*
 * Test configuration:
     MCU:             PIC16F76
 */

unsigned int i, count, cnt, time_in_ms;

// Function prototypes
void Vdelay_ms(unsigned int time);
unsigned int CheckFunc(void);

unsigned int CheckFunc() {
    if ((RC4_bit == 0) && (i == 10)) {
        i = 0;
        PORTA = 0x00;
        return 150;
    } else if ((RC3_bit == 0) && (i == 20)) {
        i = 0;
        PORTA = 0x00;
        return 150;
    } else if (RC2_bit == 0) {
        return 120;
    } else if (RC1_bit == 0) {
        return 200;
    } else if (RC0_bit == 0) {
        return 1000;
    } else if (PORTC == 0xFF) {
        return 500;
    }
    return time_in_ms;  // Return current delay if no conditions match
}

void Vdelay_ms(unsigned int time) {
    // Implement your delay function here based on time parameter
}

void main() {
    // Initialize system
    ADCON0 = 0;
    ADCON1 = 0x07;  // All digital port pins
    TRISC = 0xFF;   // Port C is input
    TRISB = 0x00;   // Port B is output
    TRISA = 0x00;   // Port A is output
    PORTC = 0xFF;
    PORTB = 0x00;   // All LEDs off
    PORTA = 0x00;

    i = 0;                // Initialize i for use in CheckFunc
    time_in_ms = 150;     // Initial delay time

    while (1) {           // Main program loop
        for (count = 0; count <= 7; count++) {
            PORTB = 0x10;
            time_in_ms = CheckFunc(); // Call CheckFunc and update delay time
            Vdelay_ms(time_in_ms);

            PORTB = 0x01;
            time_in_ms = CheckFunc();
            Vdelay_ms(time_in_ms);

            PORTB = 0x02;
            time_in_ms = CheckFunc();
            Vdelay_ms(time_in_ms);

            PORTB = 0x04;
            time_in_ms = CheckFunc();
            Vdelay_ms(time_in_ms);

            PORTB = 0x08;
            time_in_ms = CheckFunc();
            Vdelay_ms(time_in_ms);

            PORTA++;
            i += 5;
        }
        PORTA = 0x00;
        PORTB = 0x00;
        count = 0;
        i = 0;  // Reset i at the end of each outer loop iteration
    }
}

Explanation of Modifications​

  1. CheckFunc Return Type and Calls: CheckFunc now returns time_in_ms based on the condition, so it can be used directly to update time_in_ms in the loop.
  2. Vdelay_ms Parameter: Vdelay_ms() is now defined to accept time_in_ms as a parameter, allowing more flexible timing.
  3. Initialization and Reset: i is reset to 0 after each outer loop iteration to ensure the function behaves as expected on each loop start
 
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