uint32_t Read_Distance()
{
init_ultrasonic();
//let trigger pin sends signal
GPIO_ResetBits(GPIOA, GPIO_Pin_7);
delay(2);
GPIO_SetBits(GPIOA, GPIO_Pin_7);
delay(10);
GPIO_ResetBits(GPIOA, GPIO_Pin_7);
// Give some time for response
uint32_t timeout = 1000000;
while(!GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_6)) {
if(timeout -- == 0x00) {
return -1;
}
}
//if echo pin receive signal, start counting time.
uint32_t wait_time = 0;
while(GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_6) == 1) {
wait_time ++;
delay(1);
}
return wait_time/58;
}
int main (void)
{
VCOM_Init();
xprintf_output(&VCOM_putchar); // tell miniprintf to print to VCOM
init_ultrasonic();
while (1)
{
uint32_t distance_mm = measure_distance_mm();
xprintf("Measured distance: %d mm\r\n", distance_mm);
delayMS(1500); // Wait 1.5sec until next measurement
}
}
/********************************************************************************
* main(): Calls initalizing functions and contains the infinite loop for
* distance detection.
*******************************************************************************/
int main(int argc, char **argv) {
uint64_t total_time = 0;
double distance = 0;
double threshold = 10.0; // This is in cm
/* Ways to display LEDs */
char eight_rows[8] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
char six_rows[8] = {0x7E, 0x7E, 0x7E, 0x7E, 0x7E, 0x7E, 0x7E, 0x7E};
char four_rows[8] = {0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C, 0x3C};
char two_rows[8] = {0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18, 0x18};
char x[8] = {0x81, 0x42, 0x24, 0x18, 0x18, 0x24, 0x42, 0x81};
char no_lights[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
/* Handle a signal */
signal(SIGINT, sigint_handler);
printf("Signal handler set up.\n");
/* Check for command arguments */
check_args(argc, argv, &threshold);
printf("Arguments have been checked.\n");
/* Setup LED Matrix pins */
if(init_gpio() != 0) {
exit(1);
}
printf("GPIO initialized.\n");
/* Setup SPI */
if(init_spi() != 0) {
exit(1);
}
printf("SPI initialized.\n");
/* Setup ultrasonic sensor */
if(init_ultrasonic() != 0) {
exit(1);
}
printf("Ultrasonic initialized.\n");
/* Begin a never ending loop that will read from the ulstrasonic sensor
* and display lights on the LED matrix until CTRL-C is hit */
while(1){
if (read(ultrasonic_fd, &total_time, sizeof(total_time)) < 0) {
perror("ERROR: Could not read from ultrasonic device.\n");
}
/* Pretty sure the ultrasonic data sheet lied because using the formulas didn't
* get me anywhere. So, after some trial and error, I determined using a denominator
* in th range of 22750 will give me a decent distance number. */
distance = (double)total_time / 22750;
printf("Distance is %f\n", distance);
/* Distance scenarios */
if (distance > (4 * threshold)) { // Object is too far away to register
display_pattern(eight_rows);
}
else if (distance <= (4 * threshold) && distance > (3 * threshold)) { // Object is far but still registered
display_pattern(six_rows);
}
else if (distance <= (3 * threshold) && distance > (2 * threshold)) { // Object is halfway
display_pattern(four_rows);
}
else if (distance <= (2 * threshold) && distance > threshold) { // Object is getting too close
display_pattern(two_rows);
}
else { // Object has crashed =(
display_pattern(x);
usleep(500000);
display_pattern(no_lights);
usleep(500000);
}
}
}
