MODULE 2: Signals / Rhett Board SUMMER CHALLENGE Electrical Engineering: Smart Lighting Michael Rahaim, PhD Candidate Multimedia Communications Lab Smart Lighting Engineering Research Center Boston University

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Overview  Smart Lighting Kit  Voltage and Current  What is a signal?  Generating & observing signals  The Rhett Board and Mobile Studio  Experiments  Time Domain - Digital Signals  Time Domain - Analog Signals  Frequency Domain 2 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Teams  Team 1: Konstantinos & Alexis  Team 2: Andrea & Aris  Team 3: Jaun Pablo & Arjun & Ignacio  Team 4: Christy & Alexandra  Team 5: Kaileigh & Elena  Team 6: Nithin & Simon  Team 7: Adam & Andrew  Team 8: Greg & Iraj  Team 9: Jeff & Eric  Team 10: Kento & Chandler 3 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Smart Lighting Kit 4 Course website: Mobile Studio Project: Smart Lighting Lab kit contents: 2 Rhett Boards 2 USB to micro-USB cables 2 Breadboards 2 Wiring kits 2 Alligator Clips Resistors and capacitors Red, green and white LEDs Photodiode(PD) Operational amplifier (Op-Amp) Exclusive-OR (XOR) gate Lens Flashlight Tape measure Protractor Speaker Headphones Transceiver printed circuit board (PCB) o Board Components o 2 USB to serial cables (FTDI) 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Static Electricity  Atoms vs Ions  Atoms consist of neutrons, protons, and electrons  Neutrons are neutral, protons are positive, electrons are negative  Ions are electrically charged atoms (more or less electrons than protons!)  Charge  Measure of the difference in protons and electrons  Typically measured in Coulombs [C]  Charge causes objects to experience an attractive or repulsive force 5 07/08/2014 P P P P P N P N N N NN e e e e e e P P P P P N P N N N NN e e e e e

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board  Insulators and Conductors  Electrons in insulators have little freedom to move  Electrons in conductors easily move from atom to atom  Insulators: Rubber, Cotton, Wood, etc.  Conductors: Silver, Copper, aluminum, etc.  Electric Current  Electric force tends to disperse charge if possible  Current is the rate of flow of charge (opposite the flow of electrons)  Current is measured in Amperes [A] or [C/s] “Dynamic” Electricity 6 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Circuits  Continuous flow requires an “infinite” source of electrons  What is another “circuit” you’ve heard of? 7 07/08/2014 Source Sink Source Sink What is flow rate of marbles in this scenario? What is missing?

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Voltage  Another Analogy: Water Slide  Pump moves water back to the top  Pumping water to the top requires energy  This increases the Potential Energy of the water  As water flows down the slide, it releases stored energy  Water at the top of higher slides has more PE relative to ground  Relation to electric circuits  Batteries act as the “pump” in an electric circuit  Electric Potential, or Voltage [V], is the Electric PE per unit charge 8 07/08/2014 Electrons flow from the negative terminal to the positive terminal Buildup of charge at the battery terminal forces electrons to move through the circuit

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Voltage 07/08/  Differential  Potential energy is related to the “drop” from one level to another  Voltage is the electric potential difference between two points  Ground  In the water slide analogy, the ground can be a common reference  Similarly, electrical “ground” can be a common reference  Ground isn’t always exactly the same across devices!  Polarity  Some devices only allow current to flow in one direction  LEDs are polarized components.

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Signal Generator Signal Measurement System Signal Analysis  What is “Time Domain”  Types of Signals  As EE’s, we want to convert to ELECTRICAL signals!  Digital vs Analog (Discrete vs Continuous)  Input vs Output 10 07/08/2014 Output Input

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Signal Analysis  Waveform  Signals repeated indefinitely  Amplitude  Instantaneous vs Average  Period and Frequency  Period: Duration of repeating component of the signal [s]  Frequency: Number of repetitions per second [Hz]  Phase  Ranges from 0 to 360 degrees  Single Ended (SE) vs Differential (DIF)  SE: Voltage difference between a point and “ground”  DIF: Voltage difference between point A and point B  AC vs DC coupling 11 07/08/2014 t … period Phase Shift Amplitude

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Digital Signal  Discrete level signals  Consider 2-level (binary) signals that are “on” or “off”  How many states do a car’s tail lights have?  Variations in time send information!  Pulse Width and Duty Cycle 12 07/08/2014 Pulse Width t period Amplitude Pulse Width t period Amplitude Duty Cycle: 50%Duty Cycle: 25%

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Signal Generation / Observation 13 07/08/2014 Function GeneratorOscilloscope

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Rhett Board Pinout 14 Digital I/O : Digital Input/Output Pins PWM1 : Pulse Width Modulation, Channel 1 PWM2 : Pulse Width Modulation, Channel 2 3.3V : +3.3V DC DGND : Digital ground Horizontal Connector (left to right) 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Experiment I  Mobile Studio Introduction  Digital I/O  Function Generator  Oscilloscope 15 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Analog Signals 16 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Analog Signals 17 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Rhett Board Pinout 18 -V: -4V DC (capable of providing ~ 50mA) +V: +4V DC (capable of providing ~ 50mA) Impedance Analyzer (not released) GND : Analog ground Speaker - : Audio Out Speaker + : Audio Out GND : Analog ground Phones R : Audio, Out Right Channel Phones L : Audio, Out Left Channel GND : Analog ground AWG2 : Arbitrary Waveform Generator, Channel 2 GND : Analog ground AWG1 : Arbitrary Waveform Generator, Channel 1 A2- : Analog, Channel 2 Input GND : analog ground A2+ : Analog, Channel 2 Input A1- : Analog, Channel 1 Input GND : Analog ground A1+ : Analog, Channel 1 Input Vertical Connector (top to bottom) 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Experiment II  Mobile Studio – Analog Signal Generation  Oscilloscope for reading input 19 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Frequency Domain Analysis  Sine waves generate a “pure” frequency  Time domain signals have a frequency domain representation and can be generated with a combination of sine waves  Harmonics are integer multiples of a signals fundamental frequency 20 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Experiment III  Spectrum Analyzer  Arbitrary Waveform Generator (AWG)  Function generator output is a subset of potential AWG signals! 21 07/08/2014

Boston University Slideshow Title Goes Here Module 2: Signals / The Rhett Board Recap  References:    What did you today? 22 07/08/2014