Diff: HCSR04.h

Revision:

0:78b84e1ce9df

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/HCSR04.h	Tue Feb 18 21:16:23 2020 +0000
@@ -0,0 +1,46 @@
+#ifndef HCSR04_H
+#define HCSR04_H
+
+// The following lines MUST be added into the main() routine
+/*
+HCSR04_timer.start();
+HCSR04_echo.rise(&echo_start);
+HCSR04_echo.fall(&echo_end);
+HCSR04_start.attach(&pulse_trigger, 100E-3);
+*/
+
+DigitalOut HCSR04_trigger(PTC13);
+InterruptIn HCSR04_echo(PTC16); 
+Ticker HCSR04_start;
+Timer HCSR04_timer;
+float HCSR04_time, HCSR04_inches, HCSR04_cm;
+
+void HCSR04_pulse_trigger()
+{
+    HCSR04_trigger.write(1);
+    wait(10E-6);
+    HCSR04_trigger.write(0);
+}
+
+void HCSR04_echo_start()
+{
+    HCSR04_timer.reset();
+}
+
+void HCSR04_echo_end()
+{
+    HCSR04_time=HCSR04_timer.read();
+    if(HCSR04_time < 30E-3)   // delay longer than 30 ms indicates no echo
+    {
+        HCSR04_inches=HCSR04_time*13503.9*0.5;     // speed of sound = 13503.9 inches/second and distance to object is 1/2 path length;
+        HCSR04_cm=HCSR04_time*34300.0*0.5;     // speed of sound = 34300 cm/second and distance to object is 1/2 path length;
+    }
+    else
+    {
+        HCSR04_inches=-1.0;
+        HCSR04_cm=-1.0;
+    }
+}
+
+
+#endif //HCSR04_H
\ No newline at end of file