NEED HELP URGENTLY! flow meter that displays litres per hour

[moad]

for the past 2 week iv just started my first ever project to make a c program on the software called mikroc where i would get pulses in from the flow meter and calculate the flow rate of how much litres flows every hour which then outputs to the lcd, however, after using a timer of 100ms and an interrupt that occurs that does the calculations and displays on the screen. i get lots of 0's on lcd and when the water flows through the meter...i get a change of 1 . thats all. please guys i would very much appreciate it if i get help on this. also how do i read the input signal becuase i may have done it wrong. the input signal is connected to RB7 as i have chaned the interrupt pin.

pic16f877a datasheet: **broken link removed** water flow meter datasheet: **broken link removed**

this is the code:

//Prescaler 1:4; TMR1 Preload = 15536; Actual Interrupt Time : 100 ms
volatile unsigned int val;
char num [20];
int calc;
void InitTimer1(){
  T1CON         = 0x21;
  TMR1IF_bit         = 0;
  TMR1H         = 0x3C;
  TMR1L         = 0xB0;
  TMR1IE_bit         = 1;
  INTCON         = 0xC8;
}

void Interrupt(){
  if ((TMR1IF_bit) && (RBIF_bit)){
    TMR1IF_bit = 0;
    RBIF_bit   = 0;
    TMR1H         = 0x3C;
    TMR1L         = 0xB0;
    val= PORTB.F7;                //read the input signal and assign it to val
    Calc = (val * 60 / 7.5);          //calculations for the flow rate per hour
    longinttostrwithzeros(calc,num);       //displaying on screen
    Lcd_Out(1, 3, num );
  }
}


void main() {
     Lcd_Init();
     TRISB=0b10000000;       //initiallizing rb7 as the interrupt
     PORTB=0;
     InitTimer1();            //100ms timer
}

 

[paulfjujo]

hello,

you must separate and treat appart the 2 sources of interrupt

With RB7 interrupt, you must cumulate the number of event (pulse) into your variable Nb_of_pulses
and when Timer1 interrupt occurs , read the number of pulse into Nb_of_pulses
save it in another variable, ie into Amount_Pulses_per_100mS , zeroed Nb_of_pulses
and arm a flag ie; Flag to tell to the main program , a calculus is ready

Into your main programme
inside an infinite loop
loop:
just check if Flag is ON
if (FLag==1)
{
display the Amount_pulses_per_100mS on your LCD
Raz the Flag
}
goto loop

maybe you have better to use 1 sec instead of 100mS as timer1 delay...

What is the max frequency of flowmeter pulses ?
if too high, need to use Timer0 counter instead of RB7 ...