HBridgeDCMotor.h

00001 #include "mbed.h"
00002 #include "RateLimiter.h"
00003 
00004 /** A class for driving a DC motor using a full-bridge driver (H-bridge). 
00005  *
00006  * The class has an option to drive all 4 transistors gates independently by using 4 PwmOut objects,
00007  * or to drive the H-bridge with complementary driven transistors using only 2 PwmOut objects.
00008  *
00009  * Example of use:
00010  *
00011  * @code
00012  * #include "mbed.h"
00013  * #include "HBridgeDCMotor.h"
00014  *
00015  * HBridgeDCMotor motor(p21, p22);
00016  *
00017  * int main() {
00018  *     float sampleTime = 50e-3, switchingFrequency = 25e3, rampTime = 3;
00019  *     motor.configure(sampleTime, switchingFrequency, rampTime, rampTime);
00020  *     while(true) {
00021  *         motor.setDutyCycle(1);
00022  *         wait(10);
00023  *         motor.setDutyCycle(-1);
00024  *         wait(10);
00025  *     }
00026  * }
00027  * @endcode
00028  */
00029 class HBridgeDCMotor {
00030     public:
00031         /** Constructor for independently driven transistors.
00032          * H stands for high side and L for low side transistor.
00033          * A and B designate the individual half-bridges.
00034          * @param GH_A PWM signal for driving the high side transistor of the half-bridge A
00035          * @param GL_A PWM signal for driving the low side transistor of the half-bridge A
00036          * @param GH_B PWM signal for driving the high side transistor of the half-bridge B
00037          * @param GL_B PWM signal for driving the low side transistor of the half-bridge B
00038          */
00039         HBridgeDCMotor(PinName GH_A, PinName GL_A, PinName GH_B, PinName GL_B);
00040         
00041         /** Constructor for complementary driven transistors.
00042          * The high side transistors are driven directly, while the low side transistors are
00043          * complemented by the driver itself using logic circuits.
00044          * A and B designate the individual half-bridges.
00045          * @param GH_A PWM signal for driving the high side transistor of the half-bridge A
00046          * @param GH_B PWM signal for driving the high side transistor of the half-bridge B
00047          */
00048         HBridgeDCMotor(PinName GH_A, PinName GH_B);
00049         
00050         /** Configure the parameters.
00051          * @param sampleTime sample time in seconds
00052          * @param switchingFrequency switching frequency in Hz
00053          * @param rampUpTime set the ramp up time (in seconds) from 0 to maximum speed
00054          * @param rampDownTime set the ramp down time (in seconds) from maximum speed to 0
00055          */
00056         void configure(float sampleTime, float switchingFrequency, float rampUpTime, float rampDownTime);
00057         
00058         /** Set the motor speed by changing a duty cycle value.
00059          * @param dutyCycle Duty cycle value in a range of (-1, 1). Negative value means opposite direction. */
00060         void setDutyCycle(float dutyCycle);
00061         
00062         /** Set the drive in a coast mode. */
00063         void coast();
00064         
00065         /** Get the current duty cycle.
00066          * @returns the current value of the duty cycle.
00067          */
00068         float getDutyCycle();
00069         
00070     private:
00071         PwmOut *GH_A, *GL_A, *GH_B, *GL_B; // pointers to PwmOut objects
00072         RateLimiter rl;
00073         float switchingPeriod, dutyCycle, tempDutyCycle, sampleTime;
00074         bool independentGates;
00075         Ticker ticker;
00076         void adjustDutyCycle();
00077         void init();
00078 };