19 Motor Interfacing Motor physics Transistor level interface Pinky are you pondering what I m pondering Ya Brain who plugged this typewriter into our TV J wV April 5 2014 Jonathan Valvano EE445M EE380L 6 19 1 Digital Interfacing VOL is defined as the voltage at maximum IOL Family Example IOH IOL IIH IIL fan out Standard TTL 7404 0 4 mA 16 mA 40 A 1 6 mA 10 Schottky TTL 74S04 1 mA 20 mA 50 A 2 mA 10 Low Power Schottky 74LS04 0 4 mA 4 mA 20 A 0 4 mA 10 High speed CMOS 74HC04 4 mA 4 mA 1 A 1 A LM3S LM4F 2mA drive LM3S811 2 mA 2 mA 2 A 2 A LM3S LM4F 4mA drive LM3S811 4 mA 4 mA 2 A 2 A LM3S LM4F 8mA drive LM3S811 8 mA 8 mA 2 A 2 A Electrical specifications See Chapter 24 of TM4C123 5V tolerant PD0 PD1 PB7 PB6 April 5 2014 All GPIO signals are 5 V tolerant when configured as inputs except for PD4 PD5 PB0 and PB1 which are limited to 3 6 V Jonathan Valvano EE445M EE380L 6 19 2 Motor Physics Magnetic Field B Electrical Current I Wire Electromagnet Electrical Model B I L Wire F North Coil B South F F South Magnet S Rotor F emf North Magnet Stator Coil N I I April 5 2014 R F I Jonathan Valvano EE445M EE380L 6 Brush Brush Commutators I 19 3 Darlington Transistor Ib Icoil hfe 1A 1000 1mA TIP120 NPN hfe 1000 Ice 3A V LM3S LM4F PWM PWM0 April 5 2014 VCE depends on current R L 2N2222 or TIP120 Rb Rb 100 DC motor 1N914 Rb VOH Vbe Ib 3 2 5 1mA 0 5 k emf H L 200 50 125 125 PWM0 50 200 PWM0 H PWM0 Jonathan Valvano EE445M EE380L 6 L H H L L 19 4 MOSFET Interface VGS turns on VDS small IDS large V R Coil 1N914 V L LM3S LM4F PN2222 Port April 5 2014 10 k LM3S LM4F PN2222 1 k Port S IRF9540 FQP27P06 G ID D 10 k 1 k V emf D ID G S R Coil 1N914 IRF540 IRF522 Jonathan Valvano EE445M EE380L 6 L emf 19 5 H bridge Interface Both directions VOH V 1 4 VOL 1 2 5 V V 16 2 L293 1A 1Y 8 8 L293 Q1 3 A 7 5 2A 2Y 1 1 2EN April 5 2014 6 4 5 1N914 Jonathan Valvano EE445M EE380L 6 1Y Q2 4 3 A 6 Q3 2Y Q4 5 19 6 H bridge Interface PWM controls power Out controls direction 5 1 uC 1 2EN 5 9 PWM Out PWM Out 1N914 1Y 3 2Y 6 3 4EN L29 3 2 1A 7 3Y 2 A 10 3A 15 4Y 4A 4 April 5 2014 9 9 8 5 16 5 9 9 11 9 14 12 13 Jonathan Valvano EE445M EE380L 6 See L6203 pdf 19 7 H bridge Interface One Port is PWM controlling power Other port controls direction April 5 2014 Jonathan Valvano EE445M EE380L 6 19 8 Servo Motor Simple digital interface built in controller Duty cycle controls angle April 5 2014 Jonathan Valvano EE445M EE380L 6 19 9 Servo Interface Needs its own 5V regulator Duty cycle controls angle 7805 Vin 10 F uC 9S12 PWM PWM April 5 2014 5V Power Out Servo Gnd 10 F Ground In Command Angle 60o 30o 0o Jonathan Valvano EE445M EE380L 6 Command waveforms 2 5 ms 1 5 ms 0 5 ms 20 ms 19 10 Servo Software Duty cycle controls angle April 5 2014 Jonathan Valvano EE445M EE380L 6 19 11 Summary Be careful of the currents Sensors are noisy Time lag makes it unstable Component testing Visualization and control April 5 2014 Jonathan Valvano EE345M EE380L 6 19 12