Revision 8:c69fe28366d8, committed 2015-05-06

Comitter:

coyotebush

Date:

Wed May 06 04:02:08 2015 +0000

Parent:

7:939fdc8df95b

Child:

9:16b63cd4aba8

Commit message:

Distance sensing improvements

Changed in this revision

--- a/hcsr04.cpp	Wed May 06 02:53:36 2015 +0000
+++ b/hcsr04.cpp	Wed May 06 04:02:08 2015 +0000
@@ -38,11 +38,11 @@
 void HCSR04::isr_rise(void)
 {
     pulsetime.start();
+    pulsetime.reset();
 }
 void HCSR04::start(void)
 {
     pulsedur = 0;
-    distance = 0;
     
     trigger=1;
     wait_us(10);
@@ -53,8 +53,6 @@
 {
     pulsetime.stop();
     pulsedur = pulsetime.read_us();
-    distance= (pulsedur*343)/20000;
-    pulsetime.reset();
 }
 
 void HCSR04::rise (void (*fptr)(void))
@@ -66,9 +64,11 @@
     echo.fall(fptr);
 }
 
-unsigned int HCSR04::get_dist_cm()
+double HCSR04::get_dist_cm()
 {
-    return distance;
+    if (pulsedur == 0)
+        return -1;
+    return pulsedur * kMicrosecondsToCentimeters;
 }
 unsigned int HCSR04::get_pulse_us()
 {

--- a/hcsr04.h	Wed May 06 02:53:36 2015 +0000
+++ b/hcsr04.h	Wed May 06 04:02:08 2015 +0000
@@ -29,9 +29,13 @@
 /** HCSR04 Class(es)
  */
 
+// TODO(CJF): steal clever logic from https://code.google.com/p/arduino-new-ping/ ?
+
 class HCSR04
 {
 public:
+    static const double kMicrosecondsToCentimeters = 343.0 / 20000;
+    
     /** Create a HCSR04 object connected to the specified pin
     * @param pin i/o pin to connect to
     */
@@ -41,7 +45,7 @@
     /** Return the distance from obstacle in cm
     * @param distance in cms and returns -1, in case of failure
     */
-    unsigned int get_dist_cm(void);
+    double get_dist_cm(void);
     /** Return the pulse duration equal to sonic waves travelling to obstacle and back to receiver.
     * @param pulse duration in microseconds.
     */
@@ -62,7 +66,6 @@
     DigitalOut  trigger;
     InterruptIn echo;
     unsigned int pulsedur;
-    unsigned int distance;
 };
 
 #endif
\ No newline at end of file

--- a/main.cpp	Wed May 06 02:53:36 2015 +0000
+++ b/main.cpp	Wed May 06 04:02:08 2015 +0000
@@ -46,9 +46,6 @@
 }
 
 int main() {
-   double temperature;
-   unsigned int distance;
-
    logger.log("\r\n\r\nSmart Trash Can booting\r\n");
    Connector::Endpoint::plumbNetwork();
    Connector::Endpoint::start();

--- a/resource/DistanceResource.cpp	Wed May 06 02:53:36 2015 +0000
+++ b/resource/DistanceResource.cpp	Wed May 06 04:02:08 2015 +0000
@@ -2,8 +2,11 @@
 
 string DistanceResource::get() {
     char buf[10];
+    double dist;
     sensor->start();
-    wait_ms(500);
-    snprintf(buf, 10, "%d", sensor->get_dist_cm());
+    while ((dist = sensor->get_dist_cm()) < 0)
+        ;
+    //wait_ms(500);
+    snprintf(buf, 10, "%0.2f", dist);
     return string(buf);
 }
\ No newline at end of file