1. Rowan Hall 238A beard@rowan.edu http://rowan.jkbeard.com April 09, 2006 Sophomore Clinic ENGR 01-202 5, CRN 20686 Integrating the PIC and the H- Bridge James K. Beard, Ph.D.

2. Slide 2 Sophomore Clinic II April 09, 2006 Topics Driving the MOSFETs from 5 Volts The pin out of the H-bridge Connecting the H-bridge and the PIC board

3. Slide 3 Sophomore Clinic II April 09, 2006 MOSFETs in Switching Switching properties  Off When they’re off, they’re off Gate-source voltage must be below threshold voltage  On When they’re on, the drain-source resistance is very, very low The achieved on resistance is a function of the drive voltage Drive must be much higher than the threshold voltage 5 Volts drive provides sufficient drive

4. Slide 4 Sophomore Clinic II April 09, 2006 On V-I Characteristics N-ChannelP-Channel

5. Slide 5 Sophomore Clinic II April 09, 2006 Conclusion Typical characteristics from the IRC data sheets  N-channel is IRFZ24N  P-channel is IRF9Z24NPbF Data sheet shows  N-channel on resistance of 1/8 Ohm  P-channel on resistance of 2/5 Ohm  Both limit current to about 2.5 A Good to go for Sophomore Clinic Project motor drives A good choice for magnet drive – switch directly from the PIC

6. Slide 6 Sophomore Clinic II April 09, 2006 Pin-Out of the H-Bridge Board Power connector  +5 Volts, ground from the rails  Power to the motors comes from here Connectors for the motors Three redundant ground connections Eight lines to the PIC board

7. Slide 7 Sophomore Clinic II April 09, 2006 1 3 5 7 8 6 4 2 ABC D G5 G2G2 G4G4 G1G1 G3G3 G6G6 G8G8 G5G5 G7G7 G2G2 G1G1 G3G3 G4G4 V DD H 12 H 34 H 78 H 56 H 34 H 12

8. Slide 8 Sophomore Clinic II April 09, 2006 The H-Bridge Drive The MOSFETs are complementary – The P- channel is driven by the reverse polarity signal to the gate  +5 Volts is OFF  Ground is ON We want to drive them form the PIC hardware, not the software Solution  We use the PWM output of the PIC  We use the motor direction toggle from the PIC  We drive the H-bridge with hardware using these signals

9. Slide 9 Sophomore Clinic II April 09, 2006 Interface Circuitry G2G2 G4G4 G1G1 G3G3 G6G6 G8G8 G5G5 G7G7 Toggle PWM G4G4 G1G1 G2G2 G3G3 From PIC To H-Bridge

10. Slide 10 Sophomore Clinic II April 09, 2006 The Chips CMOS to provide full 5 Volt swing on logic one 4000 series to allow use in other circuits up to 15 Volts Two-chip solution for both motors  CD4011 or MC14011 quad NAND  CD4069 or MC14069 hex inverter

11. Slide 11 Sophomore Clinic II April 09, 2006 Chip Pin-Outs

12. Slide 12 Sophomore Clinic II April 09, 2006 Wiring the Interface Logic: G2 G4 G1 G3 G6 G8 G5 G7 C0C1C2C3C4......... PIN 14: HOOK TO +5VDC PIN 7: HOOK TO GND TAKE YOUR TIME – TRIPLE CHECK EVERY CONNECTION! Errors here can cause permanent damage to the uC board and/or H-Bridge! CD4011 17 14 23456 1312111098 On both ICs: CD4069 1234567 141312111098

13. Slide 13 Sophomore Clinic II April 09, 2006 The Interface Logic Wired

14. Slide 14 Sophomore Clinic II April 09, 2006 Electromagnet Drive Circuit D SG Electromagnet Output From PIC +5 Volts From Rail Or H-Bridge IRFZ24N N-Channel MOSFET (same one that the H-bridge uses) G S D