L293D.h

00001 #ifndef L293D_H
00002 #define L293d_H
00003 
00004 #include "mbed.h"
00005 
00006 /**@brief  Class to handle L293D in two modes, Pwm or Digital.
00007  * Pwm Mode requires constructing an object with two PwmOut'puts to handle Speed.
00008  * Enable, or Digital Mode requires One DigitalOut'put to Enable or Disable both sides
00009  * of the L293D driver.
00010  *
00011  * This of course requires an 'special' wiring of the driver, using one transistor for each side.
00012  * The transistor is effectively a NOT gate, assuring that the direction of the current of the 
00013  * driver output will be controlled using just one pin.
00014  *                                                  _____________
00015  *                               Enable/ Pwm --->[1] 
00016  *                   _5V__                         |      L
00017  *                     |         _______________ [2]
00018  *                    _|_       /                  |      2
00019  *                   |  |       |       ---------[3]
00020  *                   |1k|       |       |          |      9
00021  *                   |__|       |       |   (GND)[4]
00022  *                    /_________/     ( ~ )        |      3
00023  * _left            |/                  |   (GND)[5]
00024  * -.---|470ohm|----|\  (Q 2N3904)      |          |
00025  *  |               | \                 | -------[6]      D
00026  *  |                  |_(GND)                     |    
00027  *  |                                              |
00028  *  \___________________________________________ [7]
00029  *                                                 |
00030  *                                       5~15V-->[8]_____________
00031  *
00032  * Hope you get my ASCII Art.  same goes for the other side, thus allowing a complete control of the driver 
00033  * with a few pins.
00034  *
00035  * Also for Sake of Simplicity SetSpeedLeft/Right will control Motor Speed and Direction, from -1.0 to 1.0 
00036  * Reverse if < 0.
00037  */
00038 class L293D{
00039 
00040 public:
00041 
00042     /**@brief
00043      * Two PWM for speed Cpntrol & two digital outs needed for setting direction 
00044      * on each side of the L293D.
00045      * @param left:  Output to the left side of the driver
00046      * @param right: Output to the right side of the driver
00047      * @param pwmLeft: Left side PWM.
00048      * @param pwmRight: Right side PWM.
00049      */
00050     L293D( PwmOut pwmLeft, PwmOut right, DigitalOut left, DigitalOut right );
00051     
00052     
00053     /**@brief
00054      * Set the left PWM to current speed and Direction.
00055      * Values from -1.0 to 1.0, to control direction and speed,
00056      * if Enable mode, only use -1.0 & 1.0
00057      */
00058     void setSpeedLeft( float speed );
00059     
00060     
00061     /**@brief
00062      * Set the right PWM to current speed and direction.
00063      * Values from -1.0 to 1.0, to control direction and speed,
00064      * if Enable mode, only use -1.0 & 1.0
00065      * Only to use when PWM mode is declared
00066      */
00067     void setSpeedRight( float speed );
00068     
00069     
00070     /**@brief
00071      * Read the left PWM current speed & direction
00072      * Ranges from -1.0 to 1.0, as being set.
00073      * @return Current PWM duty cycle.
00074      */
00075     float getSpeedLeft();
00076     
00077     
00078     /**@brief
00079      * Read the left PWM current speed & direction.
00080      * Ranges from -1.0 to 1.0 as being set.
00081      * @return Current PWM duty cycle.
00082      */
00083     float getSpeedRight();
00084     
00085     
00086 private:
00087 
00088     DigitalOut _left;
00089     DigitalOut _right;
00090     PwmOut _pwmLeft;
00091     PwmOut _pwmRight;
00092     
00093     float _speedLeft;
00094     float _speedRight;
00095     
00096 };
00097 
00098 #endif