1. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 1Spring Quarter IR & Servos Lab 3

2. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 2Spring Quarter Servos DC Gearhead motor with interface circuitry Often used for angular positioning Can be “hacked” to act as a standard DC Gearhead motor

3. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 3Spring Quarter Servos – Handy Board Specifics Handy Board uses PWM to command servo to desired angular position Handy Board can control 2 servos (second servo requires alternate source of 5 volts) –Digital port 9 –TOC3 port (under LCD) Need to include library files –Servo.icb –AND Servo.c –OR servo.lis

4. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 4Spring Quarter Servo - Calibration Servo.c constants may need "calibrated" to make full use of servo To do so, use servo (x) command –Set MIN_SERVO_WAVETIME=0, MAX_SERVO_WAVETIME=10000 (interaction window) –Reduce x (>1400) until servo is at 0° –Increase x( 180° –In your main program, assign new values to the global variables MIN_SERVO_WAVETIME and MAX_SERVO_WAVETIME

5. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 5Spring Quarter Servo – use Load servo.lis To turn servo on – servo_on ( ); To command servo - –servo (int period); –servo_rad (float radians); –servo_deg (float degrees); To turn servo off – servo_off ( );

6. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 6Spring Quarter Infrared (IR) Basics EM wave – 10 13 - 10 14 Hz Many things give off IR –Remote controls –Sun –Fluorescent lights –Handy Board How do we avoid interference from all these sources?

7. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 7Spring Quarter IR – Specifics Use Sharp GP1U5 IR detector –Looks for a 40kHz IR pulse 40kHz? –Used to reduce interference –Also rumored to be used due to legacy remote controls (ultrasonic)

8. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 8Spring Quarter IR – Waveform Specifics Another waveform is “modulated” on this 40 kHz carrier

9. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 9Spring Quarter IR – Handy Board detection Handy Board can look for 100Hz, 125Hz signals Handy Board looks for a matching waveform by sampling and pattern matching

10. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 10Spring Quarter IR – Waveform matching Signal Stored copy of signal X X

11. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 11Spring Quarter IR – Handy Board specifics Handy Board checks incoming signal for match w/ stored copy When they match, ir_counts return a number from 1 to 255 If there is no match, 0 is returned The longer the receiver sees a valid signal, the higher the count If you look away, counts goes to 0

12. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 12Spring Quarter IR – Handy Board use Handy Board does not handle mixed mode arithmetic Must use casting operators - angle=(float)deg where deg is integer and angle is floating point IR reception can take as much as 30% of HB resources ! !

13. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 13Spring Quarter IR – Handy Board functions void set_ir_receive_frequency (int f) ; void ir_receive_on ( ); void ir_receive_off ( ); int ir_counts (int p); –Where you should note that: –ir_counts (5) => from digital port 15 –ir_counts (4) => from digital port 14

14. Engineering H193 - Team Project Gateway Engineering Education Coalition Lab 3P. 14Spring Quarter Lab Write code to seek out an IR beacon –Scan a servo over 180° –Return to angle where beacon is located Try for accuracy, fast search time