Revision 2:174ac1a5a658, committed 2018-02-09

Comitter:

fjwats

Date:

Fri Feb 09 16:22:57 2018 +0000

Parent:

1:4a5586eb1765

Commit message:

testHCSR04 us sensor

Changed in this revision

--- a/main.cpp	Thu Dec 04 08:04:55 2014 +0000
+++ b/main.cpp	Fri Feb 09 16:22:57 2018 +0000
@@ -1,23 +1,65 @@
 #include "mbed.h"
-#include "ultrasonic.h"
-
- void dist(int distance)
-{
-    //put code here to happen when the distance is changed
-    printf("Distance changed to %dmm\r\n", distance);
-}
-
-ultrasonic mu(D8, D9, .1, 1, &dist);    //Set the trigger pin to D8 and the echo pin to D9
-                                        //have updates every .1 seconds and a timeout after 1
-                                        //second, and call dist when the distance changes
-
+ 
+DigitalOut trigger(p13);
+DigitalOut myled(LED1); //monitor trigger
+DigitalOut myled2(LED2); //monitor echo
+DigitalOut myled3(LED3);
+DigitalOut myled4(LED4);
+DigitalIn  echo(p14);
+int distance = 0;
+int correction = 0;
+Timer sonar;
+ 
 int main()
 {
-    mu.startUpdates();//start mesuring the distance
-    while(1)
-    {
-        //Do something else here
-        mu.checkDistance();     //call checkDistance() as much as possible, as this is where
-                                //the class checks if dist needs to be called.
+    sonar.reset();
+// measure actual software polling timer delays
+// delay used later in time correction
+// start timer
+    sonar.start();
+// min software polling delay to read echo pin
+    while (echo==2) {};
+    myled2 = 0;
+// stop timer
+    sonar.stop();
+// read timer
+    correction = sonar.read_us();
+    printf("Approximate software overhead timer delay is %d uS\n\r",correction);
+ 
+//Loop to read Sonar distance values, scale, and print
+    while(1) {
+// trigger sonar to send a ping
+        trigger = 1;
+        myled = 1;
+        myled2 = 0;
+        sonar.reset();
+        wait_us(10.0);
+        trigger = 0;
+        myled = 0;
+//wait for echo high
+        while (echo==0) {};
+        myled2=echo;
+//echo high, so start timer
+        sonar.start();
+//wait for echo low
+        while (echo==1) {};
+//stop timer and read value
+        sonar.stop();
+//subtract software overhead timer delay and scale to cm
+        distance = (sonar.read_us()-correction)/58.0;
+        myled2 = 0;
+        printf(" %d cm \n\r",distance);
+        
+        if (distance<10) {
+            myled3= 1;
+        }
+        if (distance>=10) {
+            myled4= 1;
+        }
+        
+        
+//wait so that any echo(s) return before sending another ping
+        wait(0.2);
+        myled3 = myled4 = 0;
     }
-}
+}
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