1. EECS 373 Presentation DC motor with H-bridge Team: Bowen Xu, Chenyu Yi, Yitian Chen 1

2. 2 How to drive a motor Two functions – Rotate reversely by reverse the voltage (Appendix I) Rotate reversely by reverse the voltage – Speed increases with voltage applied LEGO 2838, without load: M + - http://www.philohome.com/motors/motorcomp.htm

3. 3 All in one – H bridge Integrating the following functions: – Capable of driving the motor in both directions (Appendix II) Capable of driving the motor in both directions – Control the speed (explain later) What’s more? – Brake(Appendix III) Brake – Free wheeling(Appendix IV) Free wheeling

4. Control the speed using PWM Can we use analog? – …Yes… But too complex – We prefer digital (Appendix V) We prefer digital Can we connect PWM output pins on MCU with motor? – No! – The motor won’t move – Or magic smoke comes out! PWM signal acts as “switch manager”(Appendix VI)switch manager – Manage big voltage source with small voltage source – Get different AVERAGE voltage with different duty cycle 4

5. R A safer way to manage the “switches” 5 M Vpwr GND R PWM1 PWM2 OUT1 OUT2

6. R 6 M Vpwr GND R PWM1 PWM2 OUT1 OUT2 Vavg GND 0 0 1 Forward 1 3.3V 0V 3.3V 0V Vavg GND

7. 77 R 7 M Vpwr GND R PWM1 PWM2 OUT1 OUT2 Vavg GND 1 1 0 Reverse 0 3.3V 0V 3.3V 0V GND Vavg

8. 8 R 8 M Vpwr GND R PWM1 PWM2 OUT1 OUT2 GND 1 0 1 Brake 1 0 GND 3.3V 0V 3.3V 0V GND

9. 99 R 9 M Vpwr GND R PWM1 PWM2 OUT1 OUT2 Vpwr 0 1 0 Brake 2 1 Vpwr 3.3V 0V 3.3V 0V Vpwr

10. 10 M Vpwr GND R PWM1 PWM2 OUT1 OUT2 EN Add one more function: ENABLE

11. 11 PWM1 PWM2 Vpwr GND OUT1 OUT2 ENABLE 1234512345 6767 Our Basic H-bridge Chip

12. LEARN TO USE MC33886 An example of using data sheet 12

13. Before we start Scenario – Use RS-540 to drive a model car – The rated voltage: 7.2V – Current for normal speed: 3A 2 Problems – Is MC33886 capable? Bear 7.2V? Supply sufficient current? – How to connect the pins 13

14. For problem 1: Properties of MC33886Properties of MC33886 Output voltage and current: – Vpwr: 5 to 12V – Max current: 5.2A Other information – PWM input frequency no higher than 10kHz 14

15. 15 PWM1 PWM2 Vpwr GND OUT1 OUT2 ENABLE 1234512345 6767 For problem 2: Pin descriptionsPin descriptions General Chip we haveMC33886 (get from data sheet)

16. 16 RS- 540 7.2V MCU PWM1 PWM2 0 1 GND Ccp D2 D1 IN2 IN1 FS OUT1 OUT2 Vpwr 30nF Connect MC33886 with MCU and motor

17. RS- 540 MCU PWM1 PWM2 0 1 GND Ccp D2 D1 IN2 IN1 FS OUT1 OUT2 Vpwr 7.2V GND Ccp D2 D1 IN2 IN1 FS OUT1 OUT2 Vpwr Dual H-bridge to get greater power! 6.03 dollar each (www.findchips.com(www.findchips.com) 5.2A 10.4A

18. Questions? 18

19. 19 Appendix I Forward and reverse +- + - M +- M + - +- + -

20. Appendix II Forward and reverse with simple H-bridge 20 - + sw1 sw2 sw3 sw4 M + - + - -+

21. Appendix III B rake with simple H-bridge 21 GND + sw1 sw2 sw3 sw4 M + - + - GND +

22. 22 - + sw1 sw2 sw3 sw4 M + - + - Appendix III B rake with simple H-bridge

23. 23 + sw1 sw2 sw3 sw4 M + - + - + Appendix III B rake with simple H-bridge

24. Appendix IV Free wheeling 24

25. Appendix V PWM and V avg 25 3.3V 0V V avg = V peak * Duty_cycle

26. Appendix VI Output voltage with PWM control 26 Vpwr = 12V Vout 3.3V 3.6V Duty cycle: 30% 12V

27. Appendix VII MC33886 Data sheet: 27 http://www.freescale.com/files/analog/doc/data_sheet/MC33886.pdf

28. Appendix VIII MC33886 Data sheet, pin descriptions 28 http://www.freescale.com/files/analog/doc/data_sheet/MC33886.pdf