Ininite loop error when print a sensor status pic18f4520

Question

I have a problem with my code, I am programming a microcontroller pic18f4520 to read two reflective sensors, but when I print a status from any sensor become a infinite loop let me explain better

example:

Sensor A
Sensor B

when sensor A is on (0) print "BAG INICIALIZE"
when sensor A and B are on (0) print "BAG IN PLACE"
when sensor A and B are off (1) print "BAG REMOVED"

The print is well but is infinite

my referencial code is: everything is inside while(1)

//reading ports when boot
//Sensor A = J13 
//Sensor B = J6

void USART_EnviaMsg(char *str);
void USART_EnviaMsg (char *msgout)
{
    char letraout;
    while(*msgout != 0x00)      //As long as I don't come across the null at the end of the string.
    {
        letraout=*msgout;       //Read the pointer letter.
        msgout++;               //pointer go forward.
        while (TXIF==0){}       //wait to send
        TXREG=letraout;         //send the letter.
    }                
}

while(1){
 if ((PORTDbits.RD3 == 0) && (J6 == 1)) 
        {
                __delay_ms(100);         //Antibounce.
       if (PORTDbits.RD3 == 0) //I check again that it is pressed.
            {
            J6 = 0;
            }
        }
      if (PORTDbits.RD3 == 1)
            J6 = 1;
            //Bolsa A - J13...
      if ((PORTDbits.RD2 == 0) && (J13 == 1)) //J13
        {
                __delay_ms(100);         //Antibounce.
      if (PORTDbits.RD2 == 0) //I check again that it is pressed.
            {
            J13 = 0;
            }
        }
      if (PORTDbits.RD2 == 1)
                J13 = 1;
       
      if (J13 == 0 && J6 == 0){
          ValorBag = 2;
          USART_EnviaMsg("BAG IN PLACE");
          USART_EnviaMsg(CRLF);
      }
      if (J13 == 0 && J6 == 1){
          ValorBag = 0;
          USART_EnviaMsg("BAG PUTTING");
          USART_EnviaMsg(CRLF);
      }
      if (J13 == 1 && J6 == 0){
          ValorBag = 0;
          USART_EnviaMsg("BAG ERROR");
          USART_EnviaMsg(CRLF);
      }
      if ((J13 && J6)== 1){
          ValorBag = 1;
          USART_EnviaMsg("BAG REMOVED");
          USART_EnviaMsg(CRLF);
      }
}

if some condition is true print infinite loop example:

"BAG REMOVED"
"BAG REMOVED"
"BAG REMOVED"
"BAG REMOVED"
"BAG REMOVED"
"BAG REMOVED"
"BAG REMOVED"

You don't seem to have a terminating condition for your loop. You have a while(1) statement but you never break out of it. — Nikhil Kumar
– Nikhil Kumar, Commented Apr 4, 2021 at 19:40
What would be the expected behaviour? Why is the current behaviour surprising? Two conditions make 4 combinations. One combination is always true in the while(1) loop. — dlask
– dlask, Commented Apr 4, 2021 at 19:42
The code itself is OK. The logic is fine and has no "bugs," but I bet that the expected behavior is to print once it changes. Also, the coding style is pretty hard to understand. — NoTengoBattery
– NoTengoBattery, Commented Apr 4, 2021 at 20:14
You are right the expected behavior is to print once it changes, the code was from an ex employee and yes is hard to understand, I have to made some changes to make it "work". — Alexis
– Alexis, Commented Apr 4, 2021 at 21:15
Masters some advice that can help me with this? the expected behavior is to print once it changes the condition but no with infinity loop — Alexis
– Alexis, Commented Apr 5, 2021 at 0:51

user5329483 · Accepted Answer · 2021-04-08 16:51:13Z

Pack both input bits in one integer. Remember its last value and write out message only if it is changed since last time, like this:

void foo()
{
    static const int SensorA=1;
    static const int SensorB=2;
    int Status =0; //Bitmap of above Bitmasks
    int lastStatus=Status; //Bitmap of above Bitmasks
    while(1)
    {
        if ((PORTDbits.RD3 == 0) && (Status & SensorA))
        {
            __delay_ms(100);         //Antibounce.
            if (PORTDbits.RD3 == 0) //I check again that it is still pressed.
            {
                Status &= ~SensorA; //Clear bit
            }
        }
        if (PORTDbits.RD3 == 1)
            Status |= SensorA; //Set bit

        if ((PORTDbits.RD2 == 0) && (Status & SensorB))
        {
            __delay_ms(100);         //Antibounce.
            if (PORTDbits.RD2 == 0) //I check again that it is still pressed.
            {
                Status &= ~SensorB; //Clear bit
            }
        }
        if (PORTDbits.RD2 == 1)
            Status |= SensorB; //Set bit

        if (Status == lastStatus) continue; //nothing changed

        lastStatus = Status; //Changed. Remember current Status. Issue Msg only once.
        switch (Status)
        {
            case 0:
                USART_EnviaMsg("A=0, B=0");
                break;
            case SensorA:
                USART_EnviaMsg("A=1, B=0");
                break;
            case SensorB:
                USART_EnviaMsg("A=0, B=1");
                break;
            case SensorA+SensorB:
                USART_EnviaMsg("A=1, B=1");
                break;
        }
    }
}

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