Interfacing PIC12F1822 with HC-SR04 ultrasonic sensor

Distance meter using PIC12F1822 microcontroller and HC-SR04 ultrasonic sensor

This topic shows how to make a simple distance meter using PIC12F1822 microcontroller and HC-SR04 ultrasonic sensor.
I'm not going to write any information about the HC-SR04 ultrasonic sensor because it's well described in its datasheet as well as the following three topics:
PIC16F84A with HC-SR04 ultrasonic sensor example
Interfacing PIC16F877A with HC-SR04 ultrasonic sensor
Interfacing PIC18F4550 Microcontroller with HC-SR04 Ultrasonic Sensor

Components List:

• PIC12F1822 Microcontroller
• HC-SR04 Ultrasonic sensor
• 1602 LCD display
• 74HC595 Shift Register
• 10K Variable Resistor
• +5V Power Source
• Breadboard
• Jumper Wires

Interfacing PIC12F1822 with HC-SR04 ultrasonic sensor circuit:
This is our example circuit schematic where internal oscillator of PIC12F1822 is used.
The LCD display is used to display the distance result.
To interface 1602 LCD with PIC12F1822 microcontroller we need 74HC595 shift register as what was done in this post:
Interfacing PIC12F1822 microcontroller with LCD display

Interfacing PIC12F1822 with HC-SR04 ultrasonic sensor CCS C code:

// Interfacing  PIC12F1822 with HC-SR04 ultrasonic sensor CCS PIC C code
// 3-Wire LCD driver must be added
// http://ccspicc.blogspot.com/
// electronnote@gmail.com
// Use at your own risk

//LCD module connections
#define LCD_DATA_PIN PIN_A0
#define LCD_CLOCK_PIN PIN_A1
#define LCD_EN_PIN PIN_A2
//End LCD module connections

#include <12F1822.h>
#fuses NOMCLR INTRC_IO
#use delay(clock = 8000000)
#include <3WireLCD.c>
#use fast_io(A)

unsigned int16 i, distance;
int1 wait_sensor(){
  i = 0;
  set_timer1(0);                                      // Reset Timer1
  while(!input(PIN_A5) && (i < 1000))
    i = get_timer1();                                 // Read Timer1 and store its value in i
  if(i > 990)
    return 0;
  else
    return 1;
}
unsigned int16 get_distance(){
  i = 0;
  set_timer1(0);
  while(input(PIN_A5) && (i < 25000))
    i = get_timer1();
  return i;
}
void main() {
  setup_oscillator(OSC_8MHZ);                         // Set internal oscillator to 8MHz
  setup_adc_ports(NO_ANALOGS);                        // Configure all pins as digital
  set_tris_a(0x20);                                   // Configure RA5 pin as input
  lcd_initialize();                                   // Initialize LCD module
  lcd_cmd(LCD_CLEAR);                                 // LCD Clear
  lcd_goto(4, 1);                                     // Go to column 4 row 1
  lcd_out("Distance:");
  SETUP_TIMER_1(T1_INTERNAL | T1_DIV_BY_2);           // Configure Timer 1 to increment by 1 every 1 us
  while(TRUE){
    // Send 10us pulse to HC-SR04 Trigger pin
    output_high(PIN_A4);
    delay_us(10);
    output_low(PIN_A4);
    // Read pulse comes from HC-SR04 Echo pin
    if(wait_sensor()) {
      distance = get_distance();
      if(distance > 24990) {
        lcd_goto(3, 2);                               // Go to column 3 row 2
        lcd_out("Out Of Range");
      }
      else {
        distance = i/58;                              // Calculate the distance
        lcd_goto(3, 2);                               // Go to column 3 row 2
        lcd_out("       cm   ");
        lcd_goto(6, 2);                               // Go to column 6 row 2
        printf(lcd_out,"%3Lu",distance);
      }
    }
    else {
      lcd_goto(3, 2);                                 // Go to column 3 row 2
      lcd_out("  Time Out  ");
    }
  delay_ms(100);
  }
}