4.0 20 volts. If supplied with less than

4.0
Arduino:The Arduino Uno is a microcontroller
based on the ATmega328. It has 14 digital input/output pins in which 6 can be
used as PWM, 6 analog inputs, a 16 MHz ceramic resonator, a USB port, a power
jack, an ICSP header, and a reset button. It contains everything needed to
support the microcontroller; simply connect it to a computer with a USB cable
or power it with a AC-to-DC adapter or battery to get started.11The Uno differs from all preceding
boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it
features the Atmega16U2 (Atmega8U2 up to version R2) programmed as a
USB-to-serial converter.”Uno” means one in Italian and
is named to mark the upcoming release of Arduino 1.0.13 The Uno and version
1.0 will be the reference versions of Arduino, moving forward. The Uno is the
latest in a series of USB Arduino boards, and the reference model for the
Arduino platform.

Fig 4.0 schematic diagram of Arduino4.0.1 Pin configuration:The Arduino reference design can use an
Atmega8, 168, or 328, Current models use anATmega328, but an Atmega8 is shown
in the diagram for reference. The pin configuration is identicalon all three
processors.12 4.0.2
Power:The Arduino Uno can be powered via the
USB connection or with an external power supply. The power source is selected
automatically.External (non-USB) power can come either from an AC-to-DC adapter
(wall-wart) or battery. TheAdapter can be connected by plugging a 2.1mm
center-positive plug into the board’s power jack. LeadsFrom a battery can be
inserted in the Gnd and Vin pin headers of the POWER connector.The board can
operate 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 be
unstable. If using more than 12V, theVoltage regulator may overheat and damage
the board. The recommended range is 7 to 12 volts.The power pins are as
follows:·        
VINThe input voltage to the arduino board
when it is using an external power source (asopposed to 5 volts from the USB
connection or other regulated power source). You can supplyvoltage through this
pin, or, if supplying voltage via the power jack, access it through this pin.·        
5V.This pin outputs a regulated 5V from the
regulator on the board. The board can be suppliedwith power either from the DC
power 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, and
candamage your board. We don’t advise it. ·        
3V3. A
3.3 volt supply generated by the on-board regulator. Maximum current draw is 50
mA.·        
GND. Ground pins. 4.0.3
Memory:The ATmega328 has 32 KB (with 0.5 KB
used for the boot loader). It also has 2 KB of SRAM and 1 KBof EEPROM (which
can be read and write with the EEPROM library). 4.0.4
Input Output:Each of the 14 digital pins on the Uno
can be used as an input or output, using pinMode(),digitalWrite(), and
digitalRead() functions. They operate at 5 volts. Each pin can provide or
receive amaximum of 40 mA and has an internal pull-up resistor (disconnected by
default) 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 the
ATmega8U2 USB-to-TTL Serial chip.·        
External Interrupts: 2 and 3. These pins can be configured to trigger an
interrupt on a lowvalue, a rising or falling edge, or a change in value. See
the attachInterrupt() function fordetails.·        
PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the
analogWrite() function.·        
SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13
(SCK). These pins support SPI communicationusing the
SPI library. ·        
LED: 13. There is a built-in LED connected to
digital 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 which
provide 10 bits of resolution (i.e.1024 different values). By default they
measure from ground to 5 volts, though is it possible to changethe upper end of
their range using the AREF pin and the analogReference() function.
Additionally, somepins have specialized functionality14There are a couple of other pins on the
board:·        
AREF. Reference voltage for the analog
inputs.Used with analogReference().·        
Reset.Bring this line LOW to reset the
microcontroller. Typically used to add a reset button toshields which block the
one on the board.See also the mapping between Arduino
pins and ATmega328 ports. The mapping for the Atmega8,168, and 328 is identical 4.1
IR MODULE SENSOR:The IR Sensor-Single is a general
purpose proximity sensor. Here we use it for collision detection. The module
consists of an IR emitter and IR receiver pair. The high precision IR receiver
always detects an IR signal.The module consists of 358 Comparator
IC. 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 without
using any additional hardware. The power consumption of this module is low. It
gives a digital output.15 

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Fig 4.1 IR module  4.1.1
PIN Configuration:The figure to the right is a top view of
the 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  4.1.2
Application Area:1.     
Obstacle detection2.     
Shaft encoder3.     
Fixed frequency detection4.     
Count RPM4.1.3
Overview of Schematic:

Fig 4.2 schematic overview The sensitivity of the IR Sensor is
tuned using the potentiometer. The potentiometer is tune able in both the
directions. Initially tune the potentiometer in clockwise direction such that
the Indicator LED starts glowing. Once that is achieved, turn the potentiometer
just enough in anti-clockwise direction to turn off the Indicator LED. At this
point the sensitivity of the receiver is maximum. Thus, it sensing distance is
maximum at that point. If the sensing distance (i.e., Sensitivity) of the
receiver is needed to be reduced, then one can tune the potentiometer in the
anti-clockwise direction from this point. Further, if the orientation of both
Tx 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, such
that they are inclined to each other at their soldered end, then their
sensitivity reduces. Tuned
sensitivity of the sensors is limited to the surroundings. Once tuned for a
particular surrounding, they will work perfectly until the IR illumination
conditions of that region nearly constant. For example, if the potentiometer is
tuned inside room/building for maximum sensitivity and then taken out in open
sunlight, it will require retuning, since sun’s rays also contain Infrared (IR)
frequencies, thus acting as a IR source (transmitter). This will disturb the
receiver’s sensing capacity. Hence it needs to be returned to work perfectly in
the new surroundings.The output of IR receiver goes low when
it receives IR signal. Hence the output pin is normally low because, though the
IR LED is continuously transmitting, due to no obstacle, nothing is reflected
back to the IR receiver. The indication LED is off. When an obstacle is
encountered, the output of IR receiver goes low, IR signal is reflected from
the obstacle surface. This drives the output of the comparator low. This output
is connected to the cathode of theLED, which then turns ON.Tuned sensitivity of the sensors is
limited to the surroundings. Once tuned for a particular surrounding, they will
work perfectly until the IR illumination conditions of that region nearly
constant. For example, if the potentiometer is tuned inside room/building for
maximum sensitivity and then taken out in open sunlight, it will require
retuning, since sun’s rays also contain Infrared (IR) frequencies, thus acting
as a IR source (transmitter). This will disturb the receiver’s sensing
capacity. Hence it needs to be returned to work perfectly in the new
surroundings.16

Fig4.3 Example of IR sensor as
pulse oximeter4.2
Tachometer:A tachometer (revolution-counter, tach,
rev-counter, RPM gauge) is an instrument measuring the rotation speed of a
shaft or disk, as in a motor or other machine. The device usually displays the
revolutions per minute (RPM) on a calibrated analogue dial, but digital
displays are increasingly common. The word comes from Greek (tachos “speed”)
and metron (“measure”). Essentially the words tachometer and
speedometer have identical meaning: a device that measures speed. It is by
arbitrary convention that in the automotive world one is used for engine and
the other for vehicle speed. In formal engineering nomenclature, more precise
terms are used to distinguish the two.17 The first mechanical tachometers were
based on measuring the centrifugal force, similar to the operation of a
centrifugal governor. The inventor is assumed to be the German engineer
Dietrich Uhlhorn; he used it for measuring the speed of machines in 1817. Since
1840, it has been used to measure the speed of locomotives.Tachometers or revolution counters on
cars, aircraft, and other vehicles show the rate of rotation of the engine’s
crankshaft, and typically have markings indicating a safe range of rotation
speeds. This can assist the driver in selecting appropriate throttle and gear
settings for the driving conditions. Prolonged use at high speeds may cause
inadequate lubrication, overheating (exceeding capability of the cooling
system), exceeding speed capability of sub-parts of the engine (for example
spring retracted valves) thus causing excessive wear or permanent damage or
failure of engines. This is more applicable to manual transmissions than to
automatics. On analogue tachometers, speeds above maximum safe operating speed
are typically indicated by an area of the gauge marked in red, giving rise to
the expression of “redlining” an engine — revving the engine up to
the maximum safe limit. The red zone is superfluous on most modernspecify
cars, since their engines typically have a revolution limiter which
electronically limits engine speed to prevent damage. Diesel engines with
traditional mechanical injector systems have an integral governor which
prevents over-speeding the engine, so the tachometers in vehicles and machinery
fitted 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 speed
range in which the engine produces maximum torque, which is of prime interest
to operators of such vehicles. Tractors fitted with a power take-off (PTO)
system have tachometers showing the engine speed needed to rotate the PTO at
the standardized speed required by most PTO-driven implements. In many
countries, tractors are required to have a speedometer for use on a road. To
save fitting a second dial, the vehicle’s tachometer is often marked with a
second 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 tachometers
with more than one speed scale. Aircraft tachometers have a green arc showing
the engine’s designed cruising speed range.18 In older vehicles, the tachometer is
driven by the RMS voltage waves from the low tension (LT) side of the ignition
coil while on others (and nearly all diesel engines, which have no ignition
system) engine speed is determined by the frequency from the alternator
tachometer output. This is from a special connection called an “AC
tap” which is a connection to one of the stator’s coil output, before the
rectifier. Tachometers driven by a rotating cable from a drive unit fitted to
the engine (usually on the camshaft) exist – usually on simple diesel-engined
machinery with basic or no electrical systems. On recent EMS found on modern
vehicles, the signal for the tachometer is usually generated from an ECU which
derives the information from either the crankshaft or camshaft speed sensor. 

Fig 4.4 Tachometer            4.3 Potentiometer:A potentiometer is a manually adjustable
variable resistor with 3 terminals. Two terminals are connected to both ends of
a resistive element, and the third terminal connects to a sliding contact,
called a wiper, moving over the resistive element. The position of the wiper
determines the output voltage of the potentiometer. The potentiometer
essentially functions as a variable voltage divider. The resistive element can
be seen as two resistors in series (potentiometer resistance), where the wiper
position determines the resistance ratio of the first resistor to the second
resistor.A potentiometer is also commonly known
as a potmeter or pot. The most common form of potmeter is the single turn
rotary potmeter. This type of pot is often used in audio volume control
(logarithmic taper) as well as many other applications. Different materials are
used to construct potentiometers, including carbon composition, cermet, wire
wound, and conductive plastic or metal film.19 4.3.1
Description: “A potentiometer is a manually
adjustable, variable resistor with three terminals. Two terminals are connected
to 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  4.3.2
Types:A wide variety of potmeters exist.
Manually adjustable potmeters can be divided in rotary or linear movement
types. The tables below list the available types and their applications.
Besides manually adjustable pots, also electronically controlled potentiometers
exist, 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  4.3.3
Digital potentiometer:Digital4potentiometers are
potentiometers which are controlled electronically. In most cases they exist of
an array of small resistive components in series. Every resistive element is equipped
with a switch which can serve as the tap-off point or virtual wiper position. A
digital pot meter can be controlled by for example up/down signals or protocols
like I²C and SPI.4.3.4
Rheostat: A potentiometer can also be wired as a
rheostat, or single variable resistance. The best way to wire a potentiometer
as a rheostat is to connect the wiper and one end terminal together, this
prevents infinite resistance if the wiper occasionally loses contact. More
information can be found on the dedicated page about rheostats 4.3.5
Characteristics:·        
 TaperThe potentiometer taper is the
relationship between the mechanical position and resistance ratio. Linear taper
and logarithmic (audio) taper are the most common forms of taper. For more
information visit the dedicated page about potentiometer taper.·        
Marking codesPotentiometers values are often marked
with a readable string indicating the total resistance, such as “100k” for a
100 k Ohm potentiometer. Sometimes a 3 digit coding system similar to smd
resistor coding is used. In this system the first digits indicate the value and
the 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 normally
indicated with a letter. The following table lists the used coding for
potentiometer taper, different standards uses the same letters which can be
confusing. It is always a good idea to double check the taper by measurement.·        
Resolution:The resolution of a potentiometer is the
the smallest possible change in resistance ratio. Wirewound resistors often
have a lower resolution because the wire turns introduce discrete steps in
resistance. Conductive plastic potmeters have the best resolution. The
resolution can be influenced by the wiper configuration, a wiper consisting of
several spread contact points increases the potentiometer resolution.·        
Hop-on and Hop-off resistanceAt the start and end of travel, the
resistive track of a potentiometer is connected to low resistance metal parts
which connect the resistive element to the end terminals. The change in
resistance when the wiper enters or exits the resistive track is known as the
hop-on and hop-off resistance. 4.4
Heart Rate Sensor Pulse Sensor is a well-designed
plug-and-play heart-rate sensor for Arduino. It can be used by students,
artists, athletes, makers, and game & mobile developers who want to easily
incorporate live heart rate data into their projects. The sensor clips onto a
fingertip or earlobe and plugs right into Arduino with some jumper cables. It
also includes an open-source monitoring app that graphs your pulse in real
time.

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 sensor
into your project, and connect to an Arduino. No soldering is required.2) Velcro Dots. These are ‘hook’ side
and are also perfectly sized to the sensor. You’ll find these velcro dots very
useful if you want to make a velcro (or fabric) strap to wrap around a finger
tips.3) Velcro strap to wrap the Pulse Sensor
around your finger.4) 3 Transparent Stickers. These are
used on the front of the Pulse Sensor to protect it from oily fingers and
sweaty earlobes.5) The Pulse Sensor has 3 holes around
the outside edge which make it easy to sew it into almost anything. The front of the sensor is the pretty
side with the Heart logo. This is the side that makes contact with the skin. On
the front you see a small round hole, which is where the LED shines through
from the back, and there is also a little square just under the LED. The square
is an ambient light sensor, exactly like the one used in cellphones, tablets,
and laptops, to adjust the screen brightness in different light conditions. The
LED shines light into the fingertip or earlobe, or other capillary tissue, and
sensor reads the light that bounces back. The back of the sensor is where the
rest of the parts are mounted. We put them there so they would not get in the
way of the sensor on the front. Even the LED we are using is a reverse mount
LED. For more about the circuit functionality, check out the Hardware page.

 

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