plant counting using ultrasonic sensor with bcm2835 lib

plantCounting.c

#include <stdio.h>
#include <bcm2835.h>
 
// defining the connections 
 
#define ultra_LT RPI_V2_GPIO_P1_16
#define ultra_LE RPI_V2_GPIO_P1_18
 
 
void setup()
{
 
// setting the pins as output
     
     
     bcm2835_gpio_fsel(ultra_LT, BCM2835_GPIO_FSEL_OUTP);
     bcm2835_gpio_fsel(ultra_LE, BCM2835_GPIO_FSEL_INPT);
     bcm2835_gpio_set_pud(ultra_LE, BCM2835_GPIO_PUD_UP);
 
}
 
 
 
// detacting plants 
int main()
{
     
    uint16_t num;
    uint16_t sum=0;
 
while(1)
{
    bcm2835_gpio_write(ultra_LT, HIGH);
    bcm2835_delay(100);
    bcm2835_gpio_write(ultra_LT, LOW);
    bcm2835_delay(500);
     
 
 
    bcm2835_gpio_read(ultra_LE, HIGH)=num;
    while (num>0)
    {
 
        sum=sum+1;
        printf("the current number of plants %d \n",sum);
    }
}
 
 
return 0;
}