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2 Table of Contents Preface... 4 This document Scope... 4 Important Safety Rules - MUST READ FIRST... 4 Section I The Basics... 6 I.1 - Basics Parts... 6 I.2 - About Resistors... 7 Resistor - Ohm s Law... 7 I.3 - Pull-up vs. Pull-down resistor... 8 How it affects the flow of current... 8 I.4 Others... 9 Potentiometer... 9 Vin vs. Vout... 9 About LED:... 9 About Diode:... 9 About Capacitor:... 9 About inductor:... 9 Section II Using HiTechnic Prototype board II.1 - Digital Input /output The Pins Map APIs II.2 - Analog Input/Output The Pins Map APIs Section III - Experiments Exp1 = Turn on LED Exp 2 = Turn on/off LED with potentiometer Exp 3 : Dim/Brighten LED with potentiometer Exp 4 : Light up 2 LEDs (connected in Parallel) Exp 5 - Control 2 LEDs with ultrasonic sensor Exp 6 Build a working light sensor Exp 7 Stabilizing light value by canceling ambient light Exp 8 - Build a working temperature sensor Exp 9 Reaction Time Measurement Challenge Create your own RGB sensor P a g e

3 Section IV - Learning I2C interface Section V More in-depth circuit concepts V.1 About Voltage Divider V.2 - Loaded vs. unloaded Voltage Divider Voltage Divider Warm-up Exercises for Review V.3 - Debouncing Software debouncing: Hardware debouncing: Section 6 - About Fritzing Electronic Design Automation Software Reference -- HiTechnic Prototype board Specification I2C Interface P a g e

4 Preface This document Scope This document Is not meant to be circuitry learning do cument! This is meant to cover the most basics in order to prepare yourself for working with 3 rd parties devices. You will use Mindstorms platform as your main controller interfacing with a prototype board on a solderless breadboard. You create create a few sensors on the breadboard and later incorporated with the mindstorms platform. You will be using RobotC as your development environment. Important Safety Rules - MUST READ FIRST Main Keys: Never wire up or hook up electronics while it is receiving power. Unplug Arduino from the computer and make sure any attached battery power is turned off or unplugged. You can hurt yourself and damage/destroy the board! Never put the Arduino down on a metal surface! Never short circuit the connection! - Watch out for conductors around you, o You are the conductors, any metallic stuff are conductors. Your fingers touch any open circuits will short the connection, that simple. o Must remove away from your circuit all possible conductors which are foreign to your system. o Especially watch out for small pins, small snails, screws, small metallic clips off, etc. o Have a specific container for all your loose pins, etc. to keep them away from your bot. - Use shortest distance and consistent color. - Modularized and Systematic testing and design. Yes, even for your wiring. o I cannot emphasize enough how important it is to practice the same principle like software development in wring. The same principal such as modularization and clear and clean organization not only also goes true with the circuit wiring, but supremely important. o Do some load/stress test for a completed sub-module, before you put in another sub-module. o Modularize to allow removal and assembling easy, to allow isolation of problematic connection. o Modularize you assembling, test each as it goes. Just like software development. - Must have clear pin maps diagram. - Use anti-static bag for storage generously - MUST keep any foreign object from the bot, even when in storage. - Remove power source when not in use, even batteries. That means, even when button is off, you should remove the physical connection to any power source. In the case of power pack, I am not saying removing the wire to the power pack, but just completely remove at least one battery. - Make sure the power supply is disconnected when wiring your circuits, especially the DC Motor or Servo Controllers. - Keep your robot in an insulted container - Must leave an easy path way to remove the power source, i.e. the battery pack. I mean something you can do within a couple of seconds max.. I mean it seriously not like the old days with the protected circuits. - Keep out moisture.. including your drink or even a sneeze 4 P a g e

5 - The battery should be positioned so it will not rub against sharp edges. A damaged, leaking battery is a safety hazard ABSOLUTELY NO spaghetti wiring. 2. Do not leave loose batteries seating in the battery pack. 3. Do not attempt to remove and put in new wire while there is power supply to it including connection to your computer, or full set of batteries in the power pack. 4. Do not keep the robot with any other foreign object in the container. 5. Do NOT stack conductors, including wires which may have non-insulated area, in-between layers of boards. 6. Avoid stacking up the tight pre-bent wires against each other. 7. Avoid running wires along pinch points. Sharp metal pieces and gears can damage the wires and their insulation. When possible, run wires through metal tubing and wire-tie them to structural components. 8. Do not throw your electronic device everywhere e.g. do not just throw your sensor in your pocket without an anti-static bag. (I know this is pretty obvious. But unfortunately, just simply saw that too many times!) 5 P a g e

6 Resistor Section I The Basics I.1 - Basics Parts HiTechnic SuperPro board for MINDSTORMS NXT Ohm resistor 3 push buttons 2 4.7k ohm resistor 2 10K ohm resistor 4 photo-resistor 2N390 transistor 1 10K ohm potentiometer 1 temperature sensor microfarad (μf) capacitor Battery Various Color and clear LED Long end = + Short end = - - The three most basic units in electricity are: - voltage (V == volts) - current (I == amps; I = V / R) - resistance (R == ohms). - Voltage is measured in volts, current is measured in amps and resistance is measured in ohms. Voltag e (Volt) Current (Amp) 6 P a g e

7 I.2 - About Resistors Black Brown Red Orange Yellow Green Blue Purple Grey White Mnemonic : Big Bad Robots On our Gearbox lunders Pass reat all Resistor - Ohm s Law In Series: R total = R 1 + R R n V = I * R total Current remains the same at each Resistor even when each resister measures different. The amount of current (think about amount of water) going through each resistor (think about various sizes or same size of pipes) will remain the same. I R1 == I R2 == == I Rn even if all R n measure different. In Parallel: R total = Current will be different at various Resistor if these resistors measure different. The amount of current going through each resistor may be the different. I R1!= I R2!=!= I Rn if all R n measure different ohms. 7 P a g e

8 I.3 - Pull-up vs. Pull-down resistor The Basic use of a pull-up or pull-down resistor is to prevent a 'floating' input to a digital circuit. A Pull-up connected from the input pin to +Vdd A Pull-down connected from the input pin to Gnd or 0V. Both have the same key function: to remove noise. How: To create a default value for a circuit to ensure that the wire is at a defined logic level even if no active devices are connected to it. The difference is that one pulls the line high, the other pulls it low. See the following diagrams: Not good. Allow floating Really BAD! Pull Up Resistor Pull Down Resistor V V V V When switch S1 is open (off), then input pin 1 is susceptible to a wide array of electrical problems. When Switch S1 is closed, it shorts the circuit. Let say there is a LED on pin1. S1 opens: LED is on S1 closes: LED is off Let say there is a LED on pin1. S1 opens: LED is off S1 closes: LED is on How it affects the flow of current Electricity behaves a bit like water, i.e. flow to where it encounters the least resistance. Electricity takes the path of least resistance and moves between 5V and input pin. Pull-down resistor Pull-up resistor e.g. switch == a push button Button not pushed, digitalread(vout) == LOW Button pushed, digitalread(vout) == HIGH e.g. switch == a push button Button not pushed, digitalread(vout) == HIGH Button pushed, digitalread(vout) == LOW 8 P a g e

9 I.4 Others Potentiometer Potentiometer, an electrical device that measures potential difference between two points in a circuit by comparison with a standard battery of known potential difference. Vin vs. Vout Vin == the power source Vout == voltage output, usually the feedback value from sensors Vin vs. Vout Vin == the power source Vout == voltage output, usually the feedback value from sensors About LED: Like resistor, LED can be used to limit amount and direction of current. Resistor and LED may be interchanged (but polarity of LED is important). About Diode: Restrict current to flow one direction only. Mainly for creating your own power source Convert AC to DC and vice versa About Capacitor: Energy storage device to smooth out voltages. Capacitance rating : How much energy it can hold for a given voltage F (micro Farads) Voltage rating : max voltage the capacity should be exposed to. Never use anything over 20V. 30V+ can be dangerous to human. Polarity is important it will blow up if it is put in a wrong direction. Total capacitance in a parallel circuit : C T =C 1 +C 2...+C n Total capacitance in a series circuit: C T =. About inductor: - Device temporarily store energy as a form of magnetic field - Coil of wire creating magnetic field To smooth out voltage 9 P a g e

10 Section II Using HiTechnic Prototype board Digital Input : B0 to B7 Digital Output : B0 to B7 Analog Input : A0 to A3 Analog Output : O0 to O1 See the complete reference. Before you program, you need to download a couple header files from BotBench.com.. For your convenienec, here are the files: common.h Hitechnic-superpro.h II.1 - Digital Input /output The Pins Map 8 digital input/output pins. MSB LSB e.g e.g. 0x40 or = or = Note: binary expression such as 0b is specific to RobotC, not ANSI-C e.g. LED connected to B4, write value 0x10 == == 0b or Recommendation: - Create Macros or enumerated types for all digital Pin Constants,eg. o #define B0 0x1 o #define B1 0x2 o o #define B7 0x80. APIs bool HTSPBsetupIO(tSensors link, ubyte mask); // to setup digital pin to output link: the sensor port; umask = the pins mask return true if successful, false otherwise ubyte HTSPBreadIO(tSensors link, ubyte mask); // to read value from digital pin the sensor port, the pins mask return the feedback value bool HTSPBwriteIO(tSensors link, ubyte mask); // to write high or low to digital pin link: the sensor port; umask = the pins mask return true if successful, false otherwise 10 P a g e

11 II.2 - Analog Input/Output Analog inputs read a voltage and returns a digital value that compares the signal to a known voltage - in this case 5V. The Hitechnic Prototype Board uses 10 bit analog to digital converters, so the value returned is between 0 and 2^10 (1023), representing voltages from 0V to 5V. The Pins Map APIs int HTSPBreadADC(tSensors link, byte channel, byte width) link: the sensor port channel : 0 or 1 (i.e. A0 or A1) width : 10 return feedback value (0 to 1023 if width=10; 0 to 255 if width=8) bool HTSPBwriteAnalog(tSensors link, byte dac, byte mode, int freq, int volt) link: the sensor port dac : HTSPB_DACO0 or HTSPB_DACO1 ( ie. O0 or O1 ) mode : waveform, such as DAC_MODE_DCOUT ( see below or the HTSPB-driver.h) freq : Hz volt : 0 to 1023 ( usually is the variable voltage read from an input port) return true if successful, false otherwise Analog output modes: - defined in Waveforms which are patterns of electrical energy over time. DAC_MODE_DCOUT Steady (DC) voltage output. * DAC_MODE_SINEWAVE Sine wave output. * these waveforms are also called alternating waveforms as they alternate from a positive direction to a negative direction constantly crossing the zero axis point. DAC_MODE_SQUAREWAVE Square wave output. * Symmetrical" waveforms timing signals, Clock pulses and Trigger pulses. DAC_MODE_SAWPOSWAVE 11 P a g e

12 Positive going sawtooth output. * DAC_MODE_SAWNEGWAVE rich in harmonics and for music synthesizers and musicians gives the quality of the sound or tonal color to their music without any distortion. Negative going sawtooth output. * DAC_MODE_TRIANGLEWAVE Triangle wave output. symmetri cal linear ramp waveform charging and discharging a capacito DAC_MODE_PWMVOLTAGE PWM square wave output. * For motors Whether the waveform is uni-directional, bi-directional, periodic, non-periodic, symmetrical, non-symmetrical, simple or complex, all electrical waveforms include the following three common characteristics: - Period (s): This is the length of time in seconds that the waveform takes to repeat itself from start to finish. - Frequency Hertz, (Hz).: This is the number of times the waveform repeats itself within a one second time period. - Amplitude (V or A): This is the magnitude or intensity of the signal waveform. 12 P a g e

13 Section III - Experiments Exp1 = Turn on LED - To Do: - And Create a circuit diagram with Fritzing Exp1.A - turns the LED on if this voltage when button is pushed. If it is a resistor, draw a resistor with the indicated color bands. Either color it, or simply mark it with 1 st letter of the color, such as R as red, Br as brown, etc. or Red Red Yellow. For the tolerance band, we will stick with gold for now. The parts needed Quantity for this circuit 220 Ohm resistor 2 10K Ohm resistor 1 Fill in or LED 1 Button Switch 1 Important: Notice that you have just done a pull-down resistor circuit. 13 P a g e

14 Exp1.B Notice that Exp1.A s circuit is a pull-down resistor circuit. Now change it to Pull-up resistor. Try that, and see what happens. Review: Pull up == the input line needs pull up i.e. high by default.. i.e input line with the resister connects to power. Pull down == the input line needs pull down i.e. low by default.... i.e input line with the resister connects to Ground. Exp1.C: Try this and see what happen. Still work as expected? Special Note: You may or may not see fluctuation in the input signal, depending on the push button. But with the pull-down or pull-down setup, you will definitely get perfectly stable high or low signal. 14 P a g e

15 Exp 2 = Turn on/off LED with potentiometer - The parts needed Qty Fill in the bands order for the resistor below, if applied. 220 Ohm resistor 1 10K potentiometer 1 LED 1 Exp 3 : Dim/Brighten LED with potentiometer Hint: HTSPBwriteAnalog(Bd, HTSPB_DACO0, DAC_MODE_DCOUT, 0, pot); 15 P a g e

16 Exp 4 : Light up 2 LEDs (connected in Parallel) Note that the LEDs are connected in parallel circuit. To each of the LED itself, the circuit to it is not in Parallel. However the circuit system as a whole is connected in Parallel. Program: Turn on led on B7 when the analog value of the potentiometer > 2 8 Turn on led on B6 when the analog value of the potentiometer > 2 7 Exp 5 - Control 2 LEDs with ultrasonic sensor When dist <=20 cm, LED on B6 is on, off otherwise When dist <=5 cm, LEG on B7 is on, off otherwise Exp 6 Build a working light sensor The parts needed Qty Fill in the bands order for the resistor below, if applied. 4.7K Ohm resistor 1 Photoresister 1 LED 1 Design your circuit by either drawing on paper or using Fritzing. Complete the circuits and program it to turn on LED when it is dark. Turn off LED when it detects bright. Your program must display the analog value of the variable resistor Photoresister, and the current going thru the LED light as well. Yes, you need to write your program to do the math. 16 P a g e

17 Exp 7 Stabilizing light value by canceling ambient light - Qty Fill in the bands order for the resistor below, if applied. 220 Ohm resistor 1 4.7K Ohm resistor 2 - to B0 LED 1 Use a clear one. Transistor 1 2N3904 Photoresistor 1 o o The program should turn the LED on and off based on the light level for both conditions. It then subtracts the reading obtained with the LED off from the reading obtained with the LED on and displays that value. Note: If there is nothing placed above the LED photocell sensor head, these readings will be very similar. However, if a white object or surface is placed a few centimeters above the sensor head, the two readings will start to differ because the white surface reflects the light from the LED when it is on. This provides a good way to detect the presence or absence of an object. You can experiment to see how different colored and different sized objects affect the results Exp 8 - Build a working temperature sensor. If it is a resistor, draw a resistor with the indicated color bands. Either color it, or simply mark it with 1 st letter of the color, such as R as red, Br as brown, etc. or Red Red Yellow. For the tolerance band, we will stick with gold for now. Parts Qty Fill in the bands order for the resistor below, if applied. 1.0 μf capacitor Ohm resistor 1 10K Ohm resistor 1 LED 1 Thermistor 1 Given formula for converting the analog signal to an actual temperature value in Celsius : TemperatureC = ((inputdata*3300)/ )/10.0; 17 P a g e

18 Exp 9 Reaction Time Measurement TBD Challenge Create your own RGB sensor Note: You will only need one resistor here connected to Ground for overall protection. Other resistors connected to the RGB pins are optional for adjusting the reflectiveness on various color. Hint: Put the Photoresistor very close to the RGB LED. But beware not to allow the pins to touch each other. To calibrate, you should always test each color with max (with white paper), and min (with black paper ). Try to avoid any Neon color, or too reflective surface. Sequence: (some RGB may be in an opposite order to the following sample) Write to B0.. read A0 ie. blue Write to B1.. read A0 ie. green Write to B2.. read A0 ie. red As each may produce various value, e.g. analog value 942 for red, 910 for green, 890 for blue when it is white. You should create a range map so that they all will be consistent from 255 when sees white. 18 P a g e

19 Section IV - Learning I2C interface In most cases of interfacing Mindstorms with other controllers, they often communicate via I2C interface. Therefore, it is important that you understand how to write a driver to communicate your Mindstorms controller with other controllers, such as Arduino, in the future. To be updated soon 19 P a g e

20 Section V More in-depth circuit concepts V.1 About Voltage Divider (watch this video VDR is to determine the voltage drop across a resistance within a series circuit. Voltage divider is also known as a potential divider. Almost all analog sensors have voltage divider. The feedback value (from Vout) reflects the variable voltage as a result of a voltage divider with at least one variable resistor. Provided: Vin = 5V, R1=2k, R2 = 3k (we know V = I * R) I = Vin / (R1+R2) (amp) I = 5v/(5000ohmz) = amp = 1 milliamp V R2 = I * R2 = 1 ma * 3000 ohmz = 3 V V R1 = I * R1 = 1 ma * 2000 ohmz = 2 V so = V out = V in * Name Math Symbol Unit Unit Symbol voltage V or E volt V current I ampere (amp) A resistance R ohm Ω power P watt W Suggested steps for wiring the left diagram below. R1 directly connected to Vin R2 on the same bus with R1 R3 directly connected to Gnd Vout in-between R2 and R3 or R1 and R1. See the voltage going to Vout changes. Vout = Vin ( ) Vout = Vin ( ) 20 P a g e

21 V.2 - Loaded vs. unloaded Voltage Divider All about whether resistors are connected in a series or parallel pattern. In all Rs are in series : R total = R 1 + R 2 + R 3 In all Rs are in parallel : R total = 1 /( + + ) 5V e.g. R 1 = 10, R 2 = 10, R Load = 10, Vin = In parallel like the diagram on the left: R total = / (1/10 + 1/10) = / 0.2 = 15 Where 1/0.2 or 5 == total R 2+ Rx load I (current for the entire circuit) = 5V / 15 ~= 0.33 Amp V R1 = 0.33Amp * 10 = 3.3V V Rx = 0.33Amp * 5 = 1.65V When Resistors are connected in parallel circuit, the total resistance is actually lower. Thus, resulting current is higher. e.g. if all 3 are in Series: R total = 1 / (1/10 + 1/10 + 1/10) = 1/.3 ~= 3.3 Ex 4: Given this diagram, figure out: - the current and voltage at each resistor - Total current in amp. R T = I = 120V / = 1.02A V (at 100 )= I * R = 1.02A * 100 = 102 V v V (at ) = 120V P a g e

22 I (at 55 ) = 18 V / 55 = 0.32A I (at 35 ) = 18 V / 35 = 0.51A I (at 95 ) = 18 V / 95 = 0.19A Voltage Divider Warm-up Exercises for Review Calculate the output voltages of these two voltage divider circuits (V A and V B ): Now, calculate the voltage between points A (red lead) and B (black lead) (V AB ). Q1) If the two resistors have the same resistance value, what is the voltage drop across one resistor? Q2) What is the voltage drop across each of the resistors if one of the resistors is ten times the value of the other? Q3) What two resistors could be used to decrease the voltage (V out ) to one quarter of its original value (V in )? Can you do the same thing with multiple copies of one type of resistor (explain how)? Q4) Derive the governing relationship for two-resistor voltage dividers, an equation that gives the voltage drop across a given resistor in terms of the total voltage drop (Vin) and the resistance values used. Hands-on Circuit Exercise 1 Using the breadboard and 5V power supply on the trainer, set up the three circuits (R1 = R2, R1 = 10 * R2, etc.) described in the Concept Question above. Use the DMM for measurements. {If this is the first time you have used a breadboard and a DMM you may want to read over the mini-modules on their use.} Fill in the chart below, including the actual measured value of the resistances, voltage drops, and currents. (You don t have to measure all of the currents; they can be calculated from the measured voltage drops and resistance values, but try to measure at least one). Voltage Divider 1: R1=R2 Voltage Divider 2: R1= 10 * R2 Voltage Divider 3: Vout = 1/4 Vin R1 (theory) R1 (theory) R1 (theory) R2 (theory) R2 (theory) R2 (theory) R1 (actual) R1 (actual) R1 (actual) R2 (actual) R2 (actual) R2 (actual) Vout (theory) Vout (theory) Vout (theory) Vout (actual) Vout (actual) Vout (actual) Current Current Current 22 P a g e

23 V.3 - Debouncing Debouncing is a provision in electronic/electrical devices having switches to prevent the spikes in output. Details: When we press any switch manually and release it, it bounces due to inherent elasticity, this causes multiple make and break of electrical contact. If the response time is very large then it won't create any problem, but if it is small then we get multiple responses for a single keypress. Software debouncing: nt ledpin = 13; int inputpin = 2; int val = 0; int bouncecheck = 0; void setup() { pinmode(ledpin, OUTPUT); pinmode(inputpin, INPUT); } // choose the pin for the LED // choose the input pin (for a pushbutton) // variable for reading the pin status // variable for debouncing // declare LED as output // declare pushbutton as input void loop(){ val = digitalread(inputpin); delay(10); bouncecheck = digitalread(inputpin); if(val == bouncecheck){ if (val == HIGH) { digitalwrite(ledpin, LOW); } else { digitalwrite(ledpin, HIGH); } } } //read input value //wait 10ms //check again //if val is the same then not a bounce //check if the input is HIGH //turn LED OFF //turn LED ON Hardware debouncing: Capacitor C1 between the digital input and ground stores a small charge when the switch opens that is released when the switch closes. This filters out the switch bounce. 23 P a g e

24 Section 6 - About Fritzing Electronic Design Automation Software Fritzing is an Electronic Design Automation (EDA) software which allows users to design and document their circuits particularly with Arduino and other electronic-based prototypes. This allows you to create printed circuit board (PCB) layouts for turning it into a robust PCB yourself or by help of a manufacturer. Download here: Try to create the following diagrams: R1 Draw another circuit for : - Replace R1 with a photoresistor. - Replace R1 with potentiometer (A0 to A3) R2 Switch This is a pull down resistor circuit. (B0 to B7) Draw one with pull up resistor circuit. R2 Sharp Analog IR distance sensor. Sharp Digital IR Switch. 24 P a g e

25 Reference -- HiTechnic Prototype board Specification Note: This section is extracted from Hitechnic.com. Should consult for any clarification and update. 3 Power Outputs o 3.3 volts regulated at 15mA from NXT o 5.0 volts regulated at 8mA from NXT o 9v volts unregulated at 8mA from NXT o 3.3 volts, 5.0 volts and 9 volts from external battery connection if applied 4 Analog Inputs (A0 A3) o volt range o 10 bit A/D conversion 8 Digital I/O (B0 B7) o Individually configurable as inputs or outputs, 0 or 3.3 volts o 220 ohm output series resistor 2 Analog Outputs (O0, O1) o volts via 10 bit D/A conversion o 7 analog modes: 1. DC voltage level 2. Sine wave 3. Square wave 4. Positive going sawtooth 5. Negative going sawtooth 6. Triangle wave 7. PWM voltage o 220 ohm output series resistor 6 Digital Strobe Outputs (S0 S3, RD, WR) o 4 can be set to logic 0 or 1 (0 or 3.3v) 1 pre-configured read strobe 1 pre-configured write strobe o 220 ohm output series resistor Onboard memory o 12k user RAM 25 P a g e

26 o 56k user program FLASH o 1Mb external storage FLASH Onboard Firmware Features o NXT I/O data and command connection o USB I/O o Onboard program execution o Multiple simultaneous user processes o Onboard datalogging Note that the digital, strobe, and analog outputs all have 220 ohm series resistors. This resistor effectivly limits the current that is availble from each output. The total current output at the 3.3v level (sourced current) should be 50mA from all outputs (D, A and 3.3v output). In the sink case, the total current can be 80mA total max. I2C Interface The SuperPro uses I2C device address of 0x10. Address Type Field 00 07H chars Sensor version number 08 0FH chars Manufacturer 10 17H chars Sensor type 42-43H byte Analog input A0; upper 8 bits, lower 2 bits 44-45H byte Analog input A1; upper 8 bits, lower 2 bits 46-47H byte Analog input A2; upper 8 bits, lower 2 bits 48-49H byte Analog input A3; upper 8 bits, lower 2 bits 4CH byte Digital inputs (bits B0 B7) 4DH byte Digital outputs (bits B0 B7) 4EH byte Digital input/output control (bits B0 B7) 50H byte Strobe output (bits S0 - S3) 51H 52H byte LED control(0=none, 1=Red, 2=Blue, 3=Red and Blue) byte Analog output O0 mode 53-54H byte Analog output O0 frequency; msb, lsb 55-56H byte Analog output O0 voltage; upper 8 bits, lower 2 bits 57H byte Analog output O1 mode 58-59H byte Analog output O1 frequency; msb, lsb 5A-5BH byte Analog output O1 voltage; upper 8 bits, lower 2 bits - The Sensor version number field returns the revision number in the format Vn.m where n is the major version number andm is the revision level. - The Manufacturer field contains HiTechnc. - The Sensor type field contains Proto. - The A0 A3 analog inputs contain the upper 8 bits in the first byte and the lower 2 bits in the second byte. - The Digital inputs field returns the state of the eight digital signals in bits P a g e

27 - The Digital outputs field sets the state of the six digital signals which have been configured as outputs. - The Digital input/output control field configures the direction of the eight digital pins B0-B7. Set the corresponding bit to 0 for input and 1 for output. - The Strong output field sets the state of the 4 general purpose strobe outputs, pins S0-S3. - The LED control field sets the state of the two on-board LEDs. Bit 0 for red LED and Bit 1 for blue LED. - The Analog mode field sets the analog mode of the analog output O0 or O1. - The Analog frequency field sets the analog freqiuency, msb, lsb. - The Analog Voltage field sets the voltage level of the analog outpuit O0 or O1. upper 8 bits, then lower 2 bits. 10 bit value corresponds to the range 0-3.3v. - The prototyping sensor board electronics derives a stabilized 3.3v internal supply from either the NXT supplied 4.3v source or an internal 4.3v source derived from an external 9v supply. Use of a low dropout regulator will permit continued operation with supply input down to 3.6v. Operation below 3.6v input will be unreliable. The board electronics also derives a stabilized 5.0v from the supplied 9v source. The 9v may be either obtained from the NXT or an external 9v source connected between the 9v and GD connections. 27 P a g e