Robotics Research Laboratory Louisiana State University

 Digital Output ◦ 8 * 8 LED matrix ◦ Techniques for LEDs control on LED matrix  Basic I/O operation ◦ Define pins on PORTas either input or output (DDRx) ◦ Output control ( PORTx) ◦ Input read (PINx)  Digital input ◦ Button ◦ Button Flag

 Ex) bitwise operations Let’s assume that we add 4 buttons on PINA4 ~ 7 and 4 LEDs on PINA0~3 LED0  PIN0, LED1  1, LED2  2, LED3  3 button0  PIN4, button1  PIN5, button2  PIN6, button3  PIN7 DDRA = 0x0F (0b ): PINA0 ~3= output, PIN4~7 = input PORTA = 0xF0 (0b ) : pull up from PIN4 to 7 for input PINA = 0xF0 (0b ): initial status of PINA All LEDs are off, all buttons are released If LED2 is only need to be on  PORTA = PORTA | 0x04 ( 0b )  PINA == 0xF4 ( 0b ) Then, if only button2 is need to be read  PINA & 0x04 ( 0b ) Button2 released: PINA ( 0b ) & 0x40 ( 0b ) 0x40 (0b )

 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

 What is it? ◦ Controlling power to inertial electrical devices ◦ Average voltage and current controlled by turning switch  What for? ◦ Modern electronic power switches ◦ The main advantage of PWM is that power loss in the switching devices is very low ◦ Relatively low cost

 Applications ◦ Fans ◦ Pumps ◦ Robotic Servo ◦ Stepper Motor ◦ Telecommunication

 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)

 How to set position of servo head ◦ /home/csc2700/csc2700/10-PWM-dimLight-01 ICR3 = 40000u;// input capture register // pulse cycle (every 40 milli-second) TCNT3 = 0;// interrupt flag register // Set the WGM mode & prescalar TCCR3A = ( 1 << WGM31 ) | ( 0 << WGM30 ) |// timer control register ( 1 << COM3A1 ) | ( 1 << COM3B1 ) | ( 1 << COM3C1 ); TCCR3B = ( 1 << WGM33 ) | ( 1 << WGM32 ) | // timer control register TIMER3_CLOCK_SEL_DIV_8; DDRE |= (( 1 << 3 ) | ( 1 << 4 ) | ( 1 << 5 ));// I/O control register uint16_t count = 0; while (1){ OCR3A = count++;// 0 ~ (pulse width), PINE3 us_spin(200); }

 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); }

 How to make it ◦ ATmega128 Stamp Board ◦ Three servo motors ◦ 3 wires (18 or 19 gauge, 12’ * 3) ◦ Battery (V 5.0)

 Let’s make it walk ◦ /home/csc2700/csc2700/10-PWM-HexaBot-01/ int count = 0; while (1){ LED_OFF(COL0_3x3);LED_OFF(COL1_3x3);LED_OFF(COL2_3x3); switch (count++ % 4){ case(0): SetPWM( PWM_PINE3, RIGHT_FRONT); SetPWM( PWM_PINE4, LEFT_BACK); SetPWM( PWM_PINE5, MID_RIGHT); break; case(1): SetPWM( PWM_PINE3, RIGHT_BACK); SetPWM( PWM_PINE4, LEFT_FRONT); SetPWM( PWM_PINE5, MID_RIGHT); break; case(2): SetPWM( PWM_PINE3, RIGHT_BACK); SetPWM( PWM_PINE4, LEFT_FRONT); SetPWM( PWM_PINE5, MID_LEFT); break; case(3): SetPWM( PWM_PINE3, RIGHT_FRONT); SetPWM( PWM_PINE4, LEFT_BACK); SetPWM( PWM_PINE5, MID_LEFT); break; } ms_spin(100); } void SetPWM( uint8_t pwmNum, uint16_t pulseWidthUSec ){ uint16_t pulseWidthTicks = pulseWidthUSec * 2; // Convert to ticks; switch ( pwmNum ){ case PWM_PINE3: OCR3A = pulseWidthTicks; break; case PWM_PINE4: OCR3B = pulseWidthTicks; break; case PWM_PINE5: OCR3C = pulseWidthTicks; break; } } // SetPWM #define PWM_PINE3 0 #define PWM_PINE4 1 #define PWM_PINE5 2 #define MID_RIGHT1300 #define MID_LEFT1700 #define RIGHT_FRONT1700 #define RIGHT_BACK1300 #define LEFT_FRONT1300 #define LEFT_BACK1700

 What is a motion in robotics? ◦ Sequence of specific poses with duration ㄴ  What motions the simple hexabot can take? ◦ Forward ◦ Backward ◦ Left turn ◦ Right turn ◦ ???

 Create a LED brightness control program, which has a plus button and a minus button ◦ The plus button is for increasing brightness of LEDs ◦ The minus button is for decreasing brightness of LEDs  (bonus) make a simple hexabot control program using 4 buttons ◦ Forward button, backward button, left turn button right turn button