A Ultrasonic car stopper project I made for my garage to inform as to how far I should pull my car forward. This project uses a MSP430 launchpad and a HSC - 04 ultrasonic range module as well as a RGB LED and a photosensitive resistor.
Youtube video: (uploading)
Schematic here: 
garage_msp430.pdf 40.14KB
5 downloads
Source here:
(i'll clean it up in abit, was having trouble with my debugger hence all the globals)
/*
* Author: Nathan Zimmerman
* Date: 6/22/13
*
* Description: A simple program to turn on a LED with the HC-SR04
* module to turn on a LED if the module detects a object closer
* than 100 centimeters
*
*/
#include "msp430g2553.h"
#include "stdint.h"
//GPIO Pins
#define trigger_pin BIT2
#define echo_input_pin BIT1
#define pot BIT0
#define bled BIT0
#define bled_setup P2DIR
#define bled_output P2OUT
#define bled_setup_on bled_setup |= bled
#define bled_on bled_output |= bled
#define bled_off bled_output &=~bled
#define rled BIT1
#define rled_setup P2DIR
#define rled_output P2OUT
#define rled_setup_on rled_setup |= rled
#define rled_on rled_output |= rled
#define rled_off rled_output &=~rled
#define gled BIT2
#define gled_setup P2DIR
#define gled_output P2OUT
#define gled_setup_on gled_setup |= gled
#define gled_on gled_output |= gled
#define gled_off gled_output &=~gled
//Ultrasound parameters
#define timer_period 62500 // 4 * 62500 = 250ms
#define trigger_pulse (timer_period - 5)
#define us_per_cm 58
#define time_to_trigger_us 450
#define distance_check 100
#define count_clk_divider 4
#define bad_measurement 40000
#define max_distance 400 //centimeters
//Statics
static uint16_t echo_pulse_counts = 0;
static uint16_t distance_set_value =0;
static uint16_t adc_val=0;
static uint16_t distance=0;
//Functions
void clk_setup_1mhz();
void setup_trigger_pulse();
void setup_gpio_echo_interrupt();
void setup_adc_input();
uint16_t compare_distance_vs_threshold();
uint16_t get_adc_counts();
uint16_t get_distance_cm();
//Main
void main(void) {
clk_setup_1mhz();
setup_trigger_pulse();
setup_gpio_echo_interrupt();
setup_adc_input();
bled_setup_on;
gled_setup_on;
rled_setup_on;
bled_off;
gled_off;
rled_off;
while(1)
{
distance = get_distance_cm();
if(distance) //Check for out of range measurement
{
if(distance<compare_distance_vs_threshold())
{
gled_off;
rled_on;
}
else
{
gled_on;
rled_off;
}
}
}
}
} // End of main
void clk_setup_1mhz() {
BCSCTL1 = CALBC1_1MHZ;
DCOCTL = CALDCO_1MHZ;
WDTCTL = WDTPW + WDTHOLD;
}
void setup_trigger_pulse() {
P1DIR |= trigger_pin;
P1OUT &= ~trigger_pin;
P1SEL |= trigger_pin;
CCR0 = timer_period;
CCTL1 = OUTMOD_7;
CCR1 = trigger_pulse;
TACTL = TASSEL_2 + MC_1+ ID_2;
__enable_interrupt();
}
void setup_gpio_echo_interrupt() {
P1DIR &= ~echo_input_pin;
P1OUT &= ~echo_input_pin;
P1IE |= echo_input_pin;
P1IES |= echo_input_pin;
P1IFG &= ~echo_input_pin;
}
void setup_adc_input() {
ADC10CTL1 |= CONSEQ1;
ADC10CTL0 |= ADC10SHT_2 + ADC10ON + MSC;
ADC10AE0 |= pot;
ADC10CTL0 |= ADC10SC + ENC;
}
uint16_t get_distance_cm() {
if(echo_pulse_counts>bad_measurement)
return 0;
else
return (echo_pulse_counts*count_clk_divider - (time_to_trigger_us))/ us_per_cm;
}
uint16_t get_adc_counts()
{
return ADC10MEM;
}
uint16_t compare_distance_vs_threshold()
{
uint32_t trip_threshold =0;
adc_val=0;
adc_val = get_adc_counts();
_delay_cycles(1);
trip_threshold = ((unsigned long)0x190*((unsigned long)adc_val))>>10;
_delay_cycles(1);
return (uint16_t)(trip_threshold & 0xFFFF);
}
#pragma vector=PORT1_VECTOR
__interrupt void Port_1(void) {
echo_pulse_counts = TAR;
P1IFG &= ~echo_input_pin;
_delay_cycles(10);
}