1. Mobile and Vehicular Network Lab 2016 WNFA LAB1 Chung-Lin Chan 2016.3.11 VLC:CamCom

2. Mobile and Vehicular Network Lab Outline Intro Implementation –Transmitter –Receiver Grading Criteria

3. Mobile and Vehicular Network Lab Intro

4. Mobile and Vehicular Network Lab Intro The term VLC is from… Visible Light Communication A kind of wireless network using visible light to transmit Apply field: vehicle network, Indoor positioning : I’m here!

5. Mobile and Vehicular Network Lab Intro The term CamCom is from… Camera Communication Using a camera sensor for VLC In Lab1, we ask you to implement a VLC system applying LED as Transmitter, and Mobile phone’s camera as Receiver ×

6. Mobile and Vehicular Network Lab Implementation -Transmitter

7. Mobile and Vehicular Network Lab Tx: Zigduino board + LED Light Implementation-Tx Equipment List: Zigduino x 1 3-color LED x 2 250Ω resistor x 6 麵包板 x 1 電線 x n

8. Mobile and Vehicular Network Lab 實驗器材圖 Implementation-Tx Zigduino installation guide: https://www.csie.ntu.edu.tw/~hsinmu/courses/_media/wn_16spring/2 016_zigduino_arduino_installationguide.pdf Use Arduino to program your zigduino board!

9. Mobile and Vehicular Network Lab Our First Zigduino Program (Blink.ino) // Pin 13 has an LED connected on most Arduino boards. int led = 13; // the setup routine runs once when you press reset: void setup() { // initialize the digital pin as an output. pinMode(led, OUTPUT); } // the loop routine runs over and over again forever: void loop() { digitalWrite(led, HIGH); // turn the LED on (HIGH is the voltage level) delay(1000); // wait for a second digitalWrite(led, LOW); // turn the LED off by making the voltage LOW delay(1000); // wait for a second } Implementation-Tx

10. Mobile and Vehicular Network Lab VLC Inspiration –Computers know but we don’t!! Implementation-Tx

11. Mobile and Vehicular Network Lab Global Shutter(G) & Rolling Shutter(R) G: Whole frame shot simultaneously R: Every row shot in different times (CMOS) Implementation-Tx Get stripes when flicker LED meet rolling shutter camera

12. Mobile and Vehicular Network Lab Still a little confused to Rolling shutter? Here’re some examples Implementation-Tx

13. Mobile and Vehicular Network Lab You can use anything to represent bits: –color, frequency, luminance, waveform, duplication,...... –Don’t forget the low sampling rate of camera (30fps) Get extra score if people cannot notice the behavior of LEDs Range your score with data rate Implementation-Tx message => bytes => behavior of LEDs Read from monitor Zigduino

14. Mobile and Vehicular Network Lab Implementation-Tx CTC Mode Clear Timer on Compare (timer == OCRnA) Generate accurate square waves –all done by hardware, won’t affected by interrupt –Can simultaneously use all 3 timers easily. Set the corresponding bits in TCCRnX(n=1,2,3 X=A,B) registers for mode selection and timer prescaler Set OCRnX for“frequency”(OCRnA)or“delay”(OCRnB,OCRnC) Frequency = 16M / prescaler / OCRnA / 2 Additional support : interrupt handler (see document)

15. Mobile and Vehicular Network Lab void setup() { // use Timer1, set control registers here pinMode(11, OUTPUT); pinMode(10, OUTPUT); pinMode(9, OUTPUT); TCCR1A = _BV(COM1A0) | _BV(COM1B0) | _BV(COM1C0); TCCR1B = _BV(WGM12) | _BV(CS12) | _BV(CS10); OCR1A = 32767; OCR1B = 16383; OCR1C = 8191; } void loop(){ // change OCRnX values to manipulate frequency OCR1A = 32767, OCR1B = 16383, OCR1C = 8191; delay(10000); // this may not be so accurate OCR1A = 16383,OCR1B = 8191,OCR1C = 4095; delay(10000); } Implementation-Tx Timer n 101 => 5 => prescaler 1024

16. Mobile and Vehicular Network Lab Implementation-Tx Some register definition

17. Mobile and Vehicular Network Lab Implementation-Tx Timer name Size of register s Control value (fill TCCRnX) Prescaler Output pin name pin in Zigduino Timer116-bit WGM = 4 COM1A/B/C = 1 CS = 1/2/3/4/5 1 / 8 / 64/ 256 / 1024 OC1A pin11 OC1B pin10 OC1C pin9 (pin11 need a jumper) Timer316-bit WGM = 4 COM3A/B/C = 1 CS = 1/2/3/4/5 1 / 8 / 64/ 256 / 1024 OC3A pin5 OC3B pin6 OC3C pin3 Timer28-bit WGM = 2 COM2A = 1 CS = 1~7 1/8/32/64 /128/256/ 1024 OC2A pin8 CTC Mode For more details http://www.atmel.com/Images/doc8266.pdf (register definition) http://www.atmel.com/Images/doc8266.pdf https://static.squarespace.com/static/511f4f0de4b09463c7605f13/t/5275c478e4 b07e72f74c7442/1383449720133/zigduino-v6c-schematic.pdf https://static.squarespace.com/static/511f4f0de4b09463c7605f13/t/5275c478e4 b07e72f74c7442/1383449720133/zigduino-v6c-schematic.pdf

18. Mobile and Vehicular Network Lab CSnX –n:timer n –X: 所需的值轉成 2 進制，所對應的第 X 位為 1 1/8/64/256/1024 →1/2/3/4/5→0001/0010/0011/0100/0101 Ex. timer 3 →n=3→CS3X prescaler=1024→5→0101→ 第 2 位和第 0 位為 1 →_BV(CS32) | _BV(CS30) Implementation-Tx

19. Mobile and Vehicular Network Lab PWM Mode(with OCRnA top) –Pulse-width modulation –Can be used to control duty cycle –http://arduino.cc/en/Tutorial/SecretsOfArduinoPWM( pi ns are different )http://arduino.cc/en/Tutorial/SecretsOfArduinoPWM –Differences in luminance and ratio of light/dark stripe width Implementation-Tx

20. Mobile and Vehicular Network Lab Implementation-Tx pinMode(6, OUTPUT); TCCR3A = _BV(COM3B1) | _BV(WGM31) | _BV(WGM30); TCCR3B = _BV(WGM32) | _BV(WGM33) | _BV(CS32) | _BV(CS30); OCR3A = 8191; OCR3B = 2047; // 25% duty cycle PWM Mode(with OCRnA top) –OCRnA define frequency –OCRnB define duty cycle

21. Mobile and Vehicular Network Lab Implementation-Tx Serial Monitor – text I/O –Input your message here!

22. Mobile and Vehicular Network Lab Implementation -Receiver

23. Mobile and Vehicular Network Lab Implementation-Rx Notice: 每支手機的相機不一定都是 30fps Rx Devices: Mobile phone’s camera

24. Mobile and Vehicular Network Lab Rx Pseudo code for all images { read image; find bounding box // where are the stripes calculate row power count stripes to get freq. // through DIP or FFT get output bit by freq. } Implementation-Rx

25. Mobile and Vehicular Network Lab Video to image: –ffmpeg –i input.avi ouput%d.jpg (supported by windows, linux, and OS X) Counting Stripes : need some DIP –find LED position, image diff, color histogram, edge detection, Fourier transform, auto-correlation, …… 3 decode basic ways : DIP, FFT, auto-correlation Implementation-Rx Video ( -> image ) -> get behavior of LEDs -> bytes -> message

26. Mobile and Vehicular Network Lab Grading Criteria

27. Mobile and Vehicular Network Lab Grade –Tx : Transmit Message 20% Workable 10% No awareness 10% Data rate (Compete ranking as 0~10 credits) –Rx : Video/Image Decode 20% Workable 10% Message Accuracy –Report : describe what team members have done(in detail), and problems encountered ( also, how you solved it ? ) (20%) –Bonus: real time... (5%) Grading Criteria

28. Mobile and Vehicular Network Lab Deadline: 4/6(Wed.) 23:59 email to wn@csie.ntu.edu.tw –Email subject:[WN]lab1_teamXX –[WN]lab1_teamXX.zip source code(tx + rx) Report(.pdf) Demo-4/6(Wed.) –Please register the demo slot. And come to CSIE R424 at that time. (TBA) –All you should do are : 1. Transmit the character string given by TA 2. Record the videos 3. Decode and get the message Grading Criteria

29. Mobile and Vehicular Network Lab 特別評分機制 90% Lab 團體成績 ( 由各個作業負責的助教決 定 ) 10% 小組互評成績 – 匿名 – 給分範圍為 -2.5 ~ 2.5 – 給分總和需等於 0 (ex 0.25/0.25/-0.25/-0.25) 目的 –Report 上的工作分配有時無法準確的表達各個組員 各自的想法，因此添加此機制作參考

30. Mobile and Vehicular Network Lab Contact to TAs : –facebook https://www.facebook.com/groups/wn15spring/ –Email : wn@csie.ntu.edu.tw –Office hour : Tue. 13:20~14:10/TBA @ CSIE R424

31. Mobile and Vehicular Network Lab Q&A