0Arduino:The Arduino Uno is a microcontrollerbased on the ATmega328. It has 14 digital input/output pins in which 6 can beused as PWM, 6 analog inputs, a 16 MHz ceramic resonator, a USB port, a powerjack, an ICSP header, and a reset button. It contains everything needed tosupport the microcontroller; simply connect it to a computer with a USB cableor power it with a AC-to-DC adapter or battery to get started.11The Uno differs from all precedingboards in that it does not use the FTDI USB-to-serial driver chip. Instead, itfeatures the Atmega16U2 (Atmega8U2 up to version R2) programmed as aUSB-to-serial converter.”Uno” means one in Italian andis named to mark the upcoming release of Arduino 1.0.
13 The Uno and version1.0 will be the reference versions of Arduino, moving forward. The Uno is thelatest in a series of USB Arduino boards, and the reference model for theArduino platform. Fig 4.
0 schematic diagram of Arduino4.0.1 Pin configuration:The Arduino reference design can use anAtmega8, 168, or 328, Current models use anATmega328, but an Atmega8 is shownin the diagram for reference. The pin configuration is identicalon all threeprocessors.12 4.0.
2Power:The Arduino Uno can be powered via theUSB connection or with an external power supply. The power source is selectedautomatically.External (non-USB) power can come either from an AC-to-DC adapter(wall-wart) or battery. TheAdapter can be connected by plugging a 2.1mmcenter-positive plug into the board’s power jack. LeadsFrom a battery can beinserted in the Gnd and Vin pin headers of the POWER connector.
The board canoperate on an external supply of 6 to 20 volts. If supplied with less than 7V,however,the 5V pin may supply less than five volts and the board may beunstable. If using more than 12V, theVoltage regulator may overheat and damagethe board. The recommended range is 7 to 12 volts.The power pins are asfollows:· VINThe input voltage to the arduino boardwhen it is using an external power source (asopposed to 5 volts from the USBconnection or other regulated power source). You can supplyvoltage through thispin, or, if supplying voltage via the power jack, access it through this pin.· 5V.
This pin outputs a regulated 5V from theregulator on the board. The board can be suppliedwith power either from the DCpower jack (7 – 12V), the USB connector (5V), or the VIN pin ofthe board(7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, andcandamage your board. We don’t advise it.
· 3V3. A3.3 volt supply generated by the on-board regulator. Maximum current draw is 50mA.· GND. Ground pins. 4.
0.3Memory:The ATmega328 has 32 KB (with 0.5 KBused for the boot loader).
It also has 2 KB of SRAM and 1 KBof EEPROM (whichcan be read and write with the EEPROM library). 4.0.4Input Output:Each of the 14 digital pins on the Unocan be used as an input or output, using pinMode(),digitalWrite(), anddigitalRead() functions.
They operate at 5 volts. Each pin can provide orreceive amaximum of 40 mA and has an internal pull-up resistor (disconnected bydefault) of 20-50 kOhms. Inaddition, some pins have specialized functions:13· Serial: 0 (RX) and 1 (TX).Used to receive (RX) and transmit (TX)TTL serial data. These pinsare connected to the corresponding pins of theATmega8U2 USB-to-TTL Serial chip.· External Interrupts: 2 and 3. These pins can be configured to trigger aninterrupt on a lowvalue, a rising or falling edge, or a change in value. Seethe attachInterrupt() function fordetails.
· PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with theanalogWrite() function.· SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13(SCK). These pins support SPI communicationusing theSPI library. · LED: 13. There is a built-in LED connected todigital pin 13.
When the pin is HIGH value, theLED is on, when the pin is LOW,it’s off.The Uno has 6 analog inputs, labeled A0 through A5, each of whichprovide 10 bits of resolution (i.e.1024 different values). By default theymeasure from ground to 5 volts, though is it possible to changethe upper end oftheir range using the AREF pin and the analogReference() function.Additionally, somepins have specialized functionality14There are a couple of other pins on theboard:· AREF.
Reference voltage for the analoginputs.Used with analogReference().· Reset.Bring this line LOW to reset themicrocontroller. Typically used to add a reset button toshields which block theone on the board.See also the mapping between Arduinopins and ATmega328 ports. The mapping for the Atmega8,168, and 328 is identical 4.
1IR MODULE SENSOR:The IR Sensor-Single is a generalpurpose proximity sensor. Here we use it for collision detection. The moduleconsists of an IR emitter and IR receiver pair. The high precision IR receiveralways detects an IR signal.The module consists of 358 ComparatorIC.
The output of sensor is high whenever it IR frequency and low otherwise.The on-board LED indicator helps user to check status of the sensor withoutusing any additional hardware. The power consumption of this module is low. Itgives a digital output.15 Fig 4.1 IR module 4.1.1PIN Configuration:The figure to the right is a top view ofthe IR Sensor module.
The following table gives its pin description. Pin No Connection Description 1 Output Digital output high or low 2 VCC Connected to circuit supply 3 GND Connected to circuit ground Table 4.0 Pin configuration 4.1.
2Application Area:1. Obstacle detection2. Shaft encoder3. Fixed frequency detection4. Count RPM4.1.3Overview of Schematic: Fig 4.2 schematic overview The sensitivity of the IR Sensor istuned using the potentiometer.
The potentiometer is tune able in both thedirections. Initially tune the potentiometer in clockwise direction such thatthe Indicator LED starts glowing. Once that is achieved, turn the potentiometerjust enough in anti-clockwise direction to turn off the Indicator LED.
At thispoint the sensitivity of the receiver is maximum. Thus, it sensing distance ismaximum at that point. If the sensing distance (i.
e., Sensitivity) of thereceiver is needed to be reduced, then one can tune the potentiometer in theanti-clockwise direction from this point. Further, if the orientation of bothTx and Rx LED’s is parallel to each other, such that both are facing outwards,then their sensitivity is maximum. If they are moved away from each other, suchthat they are inclined to each other at their soldered end, then theirsensitivity reduces.
Tunedsensitivity of the sensors is limited to the surroundings. Once tuned for aparticular surrounding, they will work perfectly until the IR illuminationconditions of that region nearly constant. For example, if the potentiometer istuned inside room/building for maximum sensitivity and then taken out in opensunlight, it will require retuning, since sun’s rays also contain Infrared (IR)frequencies, thus acting as a IR source (transmitter). This will disturb thereceiver’s sensing capacity. Hence it needs to be returned to work perfectly inthe new surroundings.The output of IR receiver goes low whenit receives IR signal. Hence the output pin is normally low because, though theIR LED is continuously transmitting, due to no obstacle, nothing is reflectedback to the IR receiver.
The indication LED is off. When an obstacle isencountered, the output of IR receiver goes low, IR signal is reflected fromthe obstacle surface. This drives the output of the comparator low.
This outputis connected to the cathode of theLED, which then turns ON.Tuned sensitivity of the sensors islimited to the surroundings. Once tuned for a particular surrounding, they willwork perfectly until the IR illumination conditions of that region nearlyconstant. For example, if the potentiometer is tuned inside room/building formaximum sensitivity and then taken out in open sunlight, it will requireretuning, since sun’s rays also contain Infrared (IR) frequencies, thus actingas a IR source (transmitter). This will disturb the receiver’s sensingcapacity. Hence it needs to be returned to work perfectly in the newsurroundings.
16 Fig4.3 Example of IR sensor aspulse oximeter4.2Tachometer:A tachometer (revolution-counter, tach,rev-counter, RPM gauge) is an instrument measuring the rotation speed of ashaft or disk, as in a motor or other machine. The device usually displays therevolutions per minute (RPM) on a calibrated analogue dial, but digitaldisplays are increasingly common. The word comes from Greek (tachos “speed”)and metron (“measure”).
Essentially the words tachometer andspeedometer have identical meaning: a device that measures speed. It is byarbitrary convention that in the automotive world one is used for engine andthe other for vehicle speed. In formal engineering nomenclature, more preciseterms are used to distinguish the two.17 The first mechanical tachometers werebased on measuring the centrifugal force, similar to the operation of acentrifugal governor. The inventor is assumed to be the German engineerDietrich Uhlhorn; he used it for measuring the speed of machines in 1817. Since1840, it has been used to measure the speed of locomotives.Tachometers or revolution counters oncars, aircraft, and other vehicles show the rate of rotation of the engine’scrankshaft, and typically have markings indicating a safe range of rotationspeeds.
This can assist the driver in selecting appropriate throttle and gearsettings for the driving conditions. Prolonged use at high speeds may causeinadequate lubrication, overheating (exceeding capability of the coolingsystem), exceeding speed capability of sub-parts of the engine (for examplespring retracted valves) thus causing excessive wear or permanent damage orfailure of engines. This is more applicable to manual transmissions than toautomatics. On analogue tachometers, speeds above maximum safe operating speedare typically indicated by an area of the gauge marked in red, giving rise tothe expression of “redlining” an engine — revving the engine up tothe maximum safe limit. The red zone is superfluous on most modernspecifycars, since their engines typically have a revolution limiter whichelectronically limits engine speed to prevent damage.
Diesel engines withtraditional mechanical injector systems have an integral governor whichprevents over-speeding the engine, so the tachometers in vehicles and machineryfitted with such engines sometimes lack a redline. In vehicles such as tractors and trucks,the tachometer often has other markings, usually a green arc showing the speedrange in which the engine produces maximum torque, which is of prime interestto operators of such vehicles. Tractors fitted with a power take-off (PTO)system have tachometers showing the engine speed needed to rotate the PTO atthe standardized speed required by most PTO-driven implements. In manycountries, tractors are required to have a speedometer for use on a road. Tosave fitting a second dial, the vehicle’s tachometer is often marked with asecond scale in units of speed. This scale is only accurate in a certain gear,but since many tractors only have one gear that is practical for use on-road,this is sufficient.
Tractors with multiple ‘road gears’ often have tachometerswith more than one speed scale. Aircraft tachometers have a green arc showingthe engine’s designed cruising speed range.18 In older vehicles, the tachometer isdriven by the RMS voltage waves from the low tension (LT) side of the ignitioncoil while on others (and nearly all diesel engines, which have no ignitionsystem) engine speed is determined by the frequency from the alternatortachometer output. This is from a special connection called an “ACtap” which is a connection to one of the stator’s coil output, before therectifier. Tachometers driven by a rotating cable from a drive unit fitted tothe engine (usually on the camshaft) exist – usually on simple diesel-enginedmachinery with basic or no electrical systems. On recent EMS found on modernvehicles, the signal for the tachometer is usually generated from an ECU whichderives the information from either the crankshaft or camshaft speed sensor. Fig 4.
4 Tachometer 4.3 Potentiometer:A potentiometer is a manually adjustablevariable resistor with 3 terminals. Two terminals are connected to both ends ofa resistive element, and the third terminal connects to a sliding contact,called a wiper, moving over the resistive element. The position of the wiperdetermines the output voltage of the potentiometer.
The potentiometeressentially functions as a variable voltage divider. The resistive element canbe seen as two resistors in series (potentiometer resistance), where the wiperposition determines the resistance ratio of the first resistor to the secondresistor.A potentiometer is also commonly knownas a potmeter or pot. The most common form of potmeter is the single turnrotary potmeter. This type of pot is often used in audio volume control(logarithmic taper) as well as many other applications.
Different materials areused to construct potentiometers, including carbon composition, cermet, wirewound, and conductive plastic or metal film.19 4.3.1Description: “A potentiometer is a manuallyadjustable, variable resistor with three terminals.
Two terminals are connectedto a resistive element; the third terminal is connected to an adjustable wiper.The position of the wiper determines the output voltage” Fig 4.5 potentiometer 4.
3.2Types:A wide variety of potmeters exist.Manually adjustable potmeters can be divided in rotary or linear movementtypes. The tables below list the available types and their applications.Besides manually adjustable pots, also electronically controlled potentiometersexist, often called digital potmeters.
20 Type Description Application Single-turn pot Single rotation of approximately 270 degrees or 3/4 of a full turn For single channel control or measurement of distance Dual-slide pot Dual slide potentiometer, single slider controlling two potentiometers in parallel. Often used for stereo control in professional audio or other applications where dual parallel channels are controlled. Multi-turn slide Constructed from a spindle which actuates a linear potentiometer wiper.
Multiple rotations (mostly 5, 10 or 20), for increased precision. Used where high precision and resolution is required. The multi turn linear pots are used as trimpots on PCB, but not as common as the worm-gear trimmer potentiometer. Motorized fade Fader which can be automatically adjusted by a servo motor Used where manual and automatic adjustment is required. Common in studio audio mixers, where the servo faders can be automatically moved to a saved configuration Table 4.1 types of potentiometers 4.3.
3Digital potentiometer:Digital4potentiometers arepotentiometers which are controlled electronically. In most cases they exist ofan array of small resistive components in series. Every resistive element is equippedwith a switch which can serve as the tap-off point or virtual wiper position. Adigital pot meter can be controlled by for example up/down signals or protocolslike I²C and SPI.4.3.
4Rheostat: A potentiometer can also be wired as arheostat, or single variable resistance. The best way to wire a potentiometeras a rheostat is to connect the wiper and one end terminal together, thisprevents infinite resistance if the wiper occasionally loses contact. Moreinformation can be found on the dedicated page about rheostats 4.
3.5Characteristics:· TaperThe potentiometer taper is therelationship between the mechanical position and resistance ratio. Linear taperand logarithmic (audio) taper are the most common forms of taper. For moreinformation visit the dedicated page about potentiometer taper.· Marking codesPotentiometers values are often markedwith a readable string indicating the total resistance, such as “100k” for a100 k Ohm potentiometer.
Sometimes a 3 digit coding system similar to smdresistor coding is used. In this system the first digits indicate the value andthe last digit indicates the multiplier. For example a 1 k Ohm would be coded as 102, meaning 10? x 102 = 1 k?.The taper of a potentiometer is normallyindicated with a letter. The following table lists the used coding forpotentiometer taper, different standards uses the same letters which can beconfusing.
It is always a good idea to double check the taper by measurement.· Resolution:The resolution of a potentiometer is thethe smallest possible change in resistance ratio. Wirewound resistors oftenhave a lower resolution because the wire turns introduce discrete steps inresistance. Conductive plastic potmeters have the best resolution. Theresolution can be influenced by the wiper configuration, a wiper consisting ofseveral spread contact points increases the potentiometer resolution.· Hop-on and Hop-off resistanceAt the start and end of travel, theresistive track of a potentiometer is connected to low resistance metal partswhich connect the resistive element to the end terminals. The change inresistance when the wiper enters or exits the resistive track is known as thehop-on and hop-off resistance. 4.
4Heart Rate Sensor Pulse Sensor is a well-designedplug-and-play heart-rate sensor for Arduino. It can be used by students,artists, athletes, makers, and game & mobile developers who want to easilyincorporate live heart rate data into their projects. The sensor clips onto afingertip or earlobe and plugs right into Arduino with some jumper cables. Italso includes an open-source monitoring app that graphs your pulse in realtime. Fig 4.6 heart rate sensor The Pulse Sensor Kit includes:1) A 24-inch Color-Coded Cable, with(male) header connectors.
You’ll find this makes it easy to embed the sensorinto your project, and connect to an Arduino. No soldering is required.2) Velcro Dots. These are ‘hook’ sideand are also perfectly sized to the sensor. You’ll find these velcro dots veryuseful if you want to make a velcro (or fabric) strap to wrap around a fingertips.3) Velcro strap to wrap the Pulse Sensoraround your finger.4) 3 Transparent Stickers.
These areused on the front of the Pulse Sensor to protect it from oily fingers andsweaty earlobes.5) The Pulse Sensor has 3 holes aroundthe outside edge which make it easy to sew it into almost anything. The front of the sensor is the prettyside with the Heart logo.
This is the side that makes contact with the skin. Onthe front you see a small round hole, which is where the LED shines throughfrom the back, and there is also a little square just under the LED. The squareis an ambient light sensor, exactly like the one used in cellphones, tablets,and laptops, to adjust the screen brightness in different light conditions. TheLED shines light into the fingertip or earlobe, or other capillary tissue, andsensor reads the light that bounces back.
The back of the sensor is where therest of the parts are mounted. We put them there so they would not get in theway of the sensor on the front. Even the LED we are using is a reverse mountLED. For more about the circuit functionality, check out the Hardware page.