main.cpp

00001 /*   PWM motor driving example on LPC1768 
00002 *
00003 *    @author: Baser Kandehir 
00004 *    @date: July 9, 2015
00005 *    @license: MIT license
00006 *     
00007 *   Copyright (c) 2015, Baser Kandehir, baser.kandehir@ieee.metu.edu.tr
00008 *
00009 *   Permission is hereby granted, free of charge, to any person obtaining a copy
00010 *   of this software and associated documentation files (the "Software"), to deal
00011 *   in the Software without restriction, including without limitation the rights
00012 *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00013 *   copies of the Software, and to permit persons to whom the Software is
00014 *   furnished to do so, subject to the following conditions:
00015 *
00016 *   The above copyright notice and this permission notice shall be included in
00017 *   all copies or substantial portions of the Software.
00018 *
00019 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00020 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00021 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00022 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00023 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00024 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00025 *   THE SOFTWARE.
00026 * 
00027 *    @description of the program: 
00028 *
00029 *    Program is written as an example for the PWM control on mbed LPC1768.
00030 *    After making neccessary connections, this program can control speed 
00031 *    and direction of a motor. Example code will increase motor speed to
00032 *    its max in 5 seconds and decrease the motor speed from max to zero
00033 *    in 5 seconds and it will keep doing this.    
00034 *    
00035 *    @connections:
00036 *-------------------------------------------------------------- 
00037 *    |LPC1768|        |Peripherals|
00038 *    Pin 21 -------->  First input of the L293D
00039 *    Pin 22 -------->  Second input of the L293D
00040 *    GND ----------->  GND of any peripheral
00041 *    VOUT (3.3 V) -->  VCC of the the motor driver
00042 *---------------------------------------------------------------
00043 *   Note: L293D is a very simple and useful motor driver that mostly used in
00044 *   robotics. For detailed info and neccessary connections for L293D, please
00045 *   refer to its datasheet.
00046 */
00047 
00048 #include "mbed.h"
00049 
00050 PwmOut PWM1(PF_8);     // pwm outputs
00051 PwmOut PWM2(PF_7);
00052 DigitalOut led1(LED1);
00053 
00054 /* Function prototype */
00055 void motorControl(bool dir, float pwmVal);
00056 
00057 int main()
00058 {
00059     
00060     led1 = 1;
00061     wait(1);
00062     led1 = 0;
00063     PWM1.write(0);       // Duty cycles are initially zero   
00064     PWM2.write(0);   
00065     PWM1.period(0.02f);   // 1 kHz pwm frequency
00066     PWM2.period(0.02f);
00067     
00068     while(1)
00069     {
00070         for(float i=0;i<1;i=i+0.01f)  // increase speed from 0 to 1 in 5 seconds (50ms*100). 
00071         {
00072             motorControl(1,i);
00073             wait(0.05f);    
00074         }  
00075         for(float i=1;i>0;i=i-0.01f)  // decrease speed from 1 to 0 in 5 seconds (50ms*100).
00076         {
00077             motorControl(0,i);
00078             wait(0.05f);    
00079         }   
00080         led1 = 1;
00081         wait(0.5);
00082         led1 = 0;
00083     }    
00084 }
00085 
00086 // This is a motor control function which controls the speed and direction of
00087 // a motor. Motor drivers like L293D can be used.
00088 void motorControl(bool dir, float pwmVal)
00089 {
00090     if(dir==1)               // forward direction
00091     {
00092         PWM2.write(0);   
00093         PWM1.write(pwmVal);        
00094     }
00095     else if(dir==0)         // reverse direction
00096     {     
00097         PWM1.write(0);       
00098         PWM2.write(pwmVal);   
00099     }    
00100 }