hcsr04.cpp

00001 /* Copyright (c) 2013 Prabhu Desai
00002  * pdtechworld@gmail.com
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
00005  * and associated documentation files (the "Software"), to deal in the Software without restriction,
00006  * including without limitation the rights to use, copy, modify, merge, publish, distribute,
00007  * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
00008  * furnished to do so, subject to the following conditions:
00009  *
00010  * The above copyright notice and this permission notice shall be included in all copies or
00011  * substantial portions of the Software.
00012  *
00013  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
00014  * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00015  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
00016  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00017  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00018  */
00019 
00020 
00021 #include "hcsr04.h"
00022 
00023 
00024 HCSR04::HCSR04(PinName TrigPin,PinName EchoPin):
00025     trigger(TrigPin), echo(EchoPin)
00026 {
00027     pulsetime.stop();
00028     pulsetime.reset();
00029     echo.rise(this,&HCSR04::isr_rise);
00030     echo.fall(this,&HCSR04::isr_fall);
00031     trigger=0;
00032 }
00033 
00034 HCSR04::~HCSR04()
00035 {
00036 }
00037 
00038 void HCSR04::isr_rise(void)
00039 {
00040     pulsetime.start();
00041 }
00042 void HCSR04::start(void)
00043 {
00044     trigger=1;
00045     wait_us(10);
00046     trigger=0;
00047 }
00048 
00049 void HCSR04::isr_fall(void)
00050 {
00051     pulsetime.stop();
00052     pulsedur = pulsetime.read_us();
00053     distance= (pulsedur*343)/20000;
00054     pulsetime.reset();
00055 }
00056 
00057 void HCSR04::rise (void (*fptr)(void))
00058 {
00059     echo.rise(fptr);
00060 }
00061 void HCSR04::fall (void (*fptr)(void))
00062 {
00063     echo.fall(fptr);
00064 }
00065 
00066 unsigned int HCSR04::get_dist_cm()
00067 {
00068     return distance;
00069 }
00070 unsigned int HCSR04::get_pulse_us()
00071 {
00072     return pulsedur;
00073 }
00074 
00075 
00076 
00077 /*******************************************************
00078    Here is a sample code usage
00079 ********************************************************* 
00080 #include "hcsr04.h"
00081 HCSR04  usensor(p25,p6);
00082 int main()
00083 {
00084     unsigned char count=0;
00085     while(1) {
00086         usensor.start();
00087         wait_ms(500); 
00088         dist=usensor.get_dist_cm();
00089         lcd.cls();
00090         lcd.locate(0,0);
00091         lcd.printf("cm:%ld",dist );
00092  
00093         count++;
00094         lcd.locate(0,1);
00095         lcd.printf("Distance =%d",count);
00096         
00097     }
00098 */