Robotics Research Laboratory Louisiana State University

 Pulse-width Modulation ◦ What for ◦ How it works ◦ Applications ◦ How to make it  Servo Motor Control ◦ What is servo motor ◦ How it works ◦ Set position of servo head  Simple Hexabot ◦ Walking ◦ Turning ◦ Control hexbot

 How to make it? ◦ Digital Out (PINx) ◦ Special Function I/O Regiser (SFR/SFIOR) ◦ Using a main program  ns_spin( int delay_time ) ; TOGGLE_PIN(PINxx) ◦ Using interrupts  Timers  PORTB – PINB5 (OCA1), PINB6 (OC1B), PINB7 (OC2)  PORTE – PINE3 (OC3C), PINE4 (OC3B), PINE5 (OC3A)

 What is it? ◦ Robotic Arms, RC-Airplane, etc. ◦ Mechanical position change  How does it work? ◦ Position Reader (Potentiometer) ◦ DC-Motor ◦ PWM DC-Motor Controller ◦ Body Frame ◦ Gears ◦ Servo Head

 How to set position of a servo head ◦ /home/csc2700/csc2700/10-PWM-Servo-01 int count = 0; while (1){ switch (count++ % 4){ case(0): OCR3A = 1000; break;// OCR3A is PINE3, 1000 is 1ms == left (0 degree) case(1): OCR3A = 3000; break;// OCR3A is PINE3, 3000 is 3ms == middle (90 degree) case(2): OCR3A = 5000; break;// OCR3A is PINE3, 5000 is 5ms == right (180 degree) case(3): OCR3A = 3000; break;// OCR3A is PINE3 } ms_spin(1000); }

MOSFET-based H-bridges

 MOSFET-based H-bridges  Recommended motor voltage (VMOT): 4.5 – 13.5 V  Logic voltage (VCC): 2.7 – 5.5 V  Output current maximum: 3 A per channel  Output current continuous: 1 A per channel (can be paralleled to deliver 2 A continuous)  Maximum PWM frequency: 100 kHz  Built-in thermal shutdown circuit  Filtering capacitors on both supply lines  Reverse-power protection on the motor supply

 The metal–oxide–semiconductor field-effect transistor

 An H bridge is an electronic circuit that enables a voltage to be applied across a load in either direction

int main(void){ InitHardware(); initPWM(); MC_HI(STANBY); MC_LO(LEFT0); MC_LO(LEFT1); MC_LO(RIGHT0); MC_LO(RIGHT1); int speed = 1000; int delay = 100; while (1){ MC_LO(LEFT0);MC_HI(LEFT1); SetPWM( PWM_PINE3, speed); SetPWM( PWM_PINE4, speed); ms_spin(delay); MC_LO(RIGHT0);MC_HI(RIGHT1); SetPWM( PWM_PINE3, speed); SetPWM( PWM_PINE4, speed); ms_spin(delay); speed += 1000; if (speed > 40000){ speed = 1000; }

 Create a DC motor speed control program, which has a clockwise button, an anti-clockwise button, and a stop button ◦ The clockwise button is for increasing speed of Motor controller toward clockwise (speed down for anti-clockwise) ◦ The anti-clockwise button is for increasing speed of Motor controller toward anti-clockwise (speed down for clockwise) ◦ The stop button is for stop DC motor