initial cleanup and mapping

examples/echo.c

@@ -0,0 +1,83 @@
+/*
+ * blink.c:
+ *	Standard "blink" program in wiringPi. Blinks an LED connected
+ *	to the first GPIO pin.
+ *
+ * Copyright (c) 2012-2013 Gordon Henderson. <projects@drogon.net>
+ ***********************************************************************
+ * This file is part of wiringPi:
+ *	https://projects.drogon.net/raspberry-pi/wiringpi/
+ *
+ *    wiringPi is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU Lesser General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    wiringPi is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Lesser General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Lesser General Public License
+ *    along with wiringPi.  If not, see <http://www.gnu.org/licenses/>.
+ ***********************************************************************
+ */
+
+#include <stdio.h>
+#include <wiringPi.h>
+#include <sys/time.h>
+
+#define	TRIG   15	
+#define	ECHO   16	
+
+float disT(void) 
+{
+  struct timeval tv1;
+  struct timeval tv2;
+
+  long start, stop;
+  float dis;
+  
+  digitalWrite(TRIG, LOW);
+  delayMicroseconds(2);
+
+  digitalWrite(TRIG, HIGH);
+  delayMicroseconds(10);
+  digitalWrite(TRIG, LOW);
+
+  while(!(digitalRead(ECHO) == 1)) {
+    gettimeofday(&tv1, NULL);
+  }
+
+  while(!(digitalRead(ECHO) == 0)) {
+    if(tv2.tv_sec - tv1.tv_sec > 10) break;
+    gettimeofday(&tv2, NULL);
+  }
+
+
+  start = tv1.tv_sec * 1000000  + tv1.tv_usec;
+  stop = tv2.tv_sec * 1000000  + tv2.tv_usec;
+
+  dis = (float) (stop - start) / 1000000 * 34000 / 2;
+
+  return dis;
+}
+
+int main (void)
+{
+  float dis;
+
+  wiringPiSetup () ;
+
+  pinMode(TRIG, OUTPUT);
+  pinMode(ECHO, INPUT);
+
+  while(1) 
+  {
+    dis = disT();
+    printf("dis: %f \n", dis);
+    delay(1200);
+  }
+
+  return 0 ;
+}