Lecture 3 - Input and Output Devices

Question 1

What are analog devices and how do they operate?

Answer 1

1) Smooth operator; it works in a continuous and flowing manner, the same way in which they deal with information
2) These devices operate using analog signals
3) To interact with them in a Raspberry Pi environment, they first have to be converted into digital signals through the use of an external ADC

Question 2

What are digital devices and how do they operate?

Answer 2

1) Digital devices break everything into steps making them more precise and easy to manage
2) They operate by using digital signals which come through a built-in ADC

Question 3

Input Devices

Answer 3

Hardware or an external device which is used to send information to a computer; allows users to communicate whether it is direct or indirect (communicating refers to the ability to input data or commands), they convert physical data/information into computer signals

Question 4

What are examples of input devices?

Answer 4

Keyboards, mouse, microphone, etc

Question 5

Output Devices

Answer 5

Opposite to an input device: sends out information/data (from a computer to a different device or user)

Question 6

What are examples of output devices?

Answer 6

Screen, displays, printer, etc

Question 7

What can be said about the solderless breadboard protortyping technique?

Answer 7

1) Non-permanant connection
2) Relatvely fragile
3) Most typical way to arrange systems

Question 8

What can be said about the stripboard prototyping technique?

Answer 8

1) Each row is an electrical connection
2) Robust method of implementation
3) Can have things soldered to it for a permanant electrical/mechanical technique

Question 9

What can be said about the printed circuit board prototyping technique?

Answer 9

1) Most complexe version
2) Designed specifically for a specific function (custom made)

Question 10

What is soldering?

Answer 10

A process in which two or more metal items arre joined together by melting and then flowing a conductive metal between the joint; it is a technique used to form permanant mech/elect connections between components

Question 11

Name all input devices that have been taught in this course

Answer 11

1) Push Button
2) Light Sensors
3) Temperature Sensors
4) Strain Gauges
5) Pressure Sensors
6) Sound Sensors
7) Distance Sensors
8) Accelerometer
9) Pi Camera

Question 12

Name all output devices that have been taught in this course

Answer 12

1) LEDs
2) Buzzer/Beeper
3) LCDs (Liquid Crystal Display)
4) DC Motor
5) Stepper Motor
6) Servo Motor

Question 13

Sound Sensors
(What is it and how it works)

Answer 13

1) Senses sound levels
2) Translates the amplitude of an sonor volume into an electrical voltage for sensing sound level

Question 14

What is the role of the diaphragm in sound sensors?

Answer 14

Generates an electrical signal when it vibrates

Question 15

Push Button
(What is it and how it works)

Answer 15

1) Used as an input device; tells the computer when it has been pressed
2) Acts as a switch; when pressed = the voltage matches on either side of the button

Question 16

Light Sensors
(What is it and how it works)

Answer 16

1) Used to detect the amount of light striking it
2) LDR: Can be used as an analog light sensor
3) Resistance increases when light decreases
4) Resistance decreases when light increases

Question 17

Temperature Sensors
(What is it and how it works)

Answer 17

1) Detect their surrounding environment’s temperature
2) There are two types of thermistors: NTC (Negative Temp Coefficient) and PTC (Positive Temp Coefficient)
3) NTC = Temp sensor/inrush current limiter
4) PTC = Protection against overcurrent conditions and resettable fuses

Question 18

Strain Gauges
(What is it and how it works)

Answer 18

1) Measures electrical resistance changes in response to the strain applied on the device
2) Takes advantage of the electrical conductance’s dependance on the conductors’ geometry

Question 19

What are the two non-neutral states of strain gauges?

Answer 19

1) Tension: Area narrows + resistance increases
2) Area thickens + resistance decreases
(Grid is patterned in such a way that there is a linear change and electrical resistances when strain is applied in a single specific direction)

Question 20

What is the formula to calculate strain?

Answer 20

Strain = (change in dimension / original dimension) = (change in resistance / original resistance)

Question 21

Pressure Sensors
(What is it and how it works)

Answer 21

1) Used to measure the amount of pressure applied
2) Produces output signals directly proportional to the amount of pressure applied

Question 22

What is an Absolute Pressure Sensor?

Answer 22

Measures pressure relative to perfect vacuum

Question 23

What is a Gauge Pressure Sensor?

Answer 23

Measures the pressure relative to atmospheric pressure

Question 24

What is a Differential Pressure Sensor?

Answer 24

Measure the difference in between two pressures

Question 25

What is a Sealed Pressure Sensor?

Answer 25

Measures pressure relative to a fixed pressure value

Question 26

What are the 4 different types of pressure sensors?

Answer 26

1) Absolute Pressure Sensor
2) Gauge Pressure Sensor
3) Differential Pressure Sensor
4) Sealed Pressure Sensor

Question 27

What are the different designs for these pressure sensors?

Answer 27

1) Piezoresisitive Strain Gauge
2) Capacitive
3) Electromagnetic
4) Piezoelectric

Question 28

Define a piezoresisitive strain gauge design for pressure sensors

Answer 28

Uses piezoresisitve resistance changes as pressure deforms the material

Question 29

Define a capacitive design for pressure sensors

Answer 29

Variable capacitor detects strain due to applied pressure; capacitance then decreases as the pressure deforms the diaphragm

Question 30

Define a electromagnetic design for pressure sensors

Answer 30

Changes in inductance allows the measuring of the displacement of a diaphragm

Question 31

Define a piezoelectric design for pressure sensors

Answer 31

Uses the piezoelectric effect in select materials where electric charge accumulates in certain solids in response to applied mechanical stress

Question 32

Distance Sensors
(What is it and how it works)

Answer 32

1) Uses sound to determine the distance between the object and the sensor
2) Emit a sound waves at a frequency outside of the hearing range that reflect and are then received back by the sensor; the distance is calculated based on the time between the sending and the receiving signal (Time of flight)

Question 33

Accelerometer
(What is it and how it works)

Answer 33

1) Detects changes in acceleration
2) Analog version: A variable voltage caused by applied acceleration is converted into an equivalent acceleration

Question 34

Pi Camera
(What is it and how it works)

Answer 34

1) Takes high-definition pictures and videos
2) Camera Serial Interface (CSI)
3) Attaches itself with the use of a ribon cable to the CSI port on the raspberry pi

Question 35

LEDs
(What is it and how it works)

Answer 35

1) Emits a narrow bandwidth of visible light (different wavelengths = different colors)
2) Two terminal devices: Cathode (Shorter probe/ notch = negative) and Anode (Longer probe = positive)

Question 36

What is a diode?

Answer 36

A type of electronic component which allows current to flow in one direction only

Question 37

Buzzer/Beeper
(What is it and how it works)

Answer 37

1) Audio-signaling device (can be one of three types: mechanical, electrical, or piezoelectric)
2) Piezo type: Piezo vibration within a molded case. Emits sound when an applied voltage causes the piece inside to vibrate

Question 38

LCDs
(What is it and how it works)

Answer 38

1) Uses liquid crystal to produce a visible image
2) 16 character/line
3) 5 x 7 pixel matric for each individual character

Question 39

DC Motor
(What is it and how it works)

Answer 39

1) Direct Current (DC) Motor
2) Two-wire (GND and power) continuous rotations motor
3) Speed is controlled by PWM (Pulse Width Modulation); limits the rotations compared to it’s default 100% (when it’s completely on)

Question 40

Stepper Motor
(What is it and how it works)

Answer 40

1) Same as the DC motor with the difference being they move in discrete steps
2) Coils are organized in “phases” (groups); energizes each group in a sequence hence, rotation is done one step at a time
3) Computer controlled = Precise position/speed

Question 41

Servo Motor
(What is it and how it works)

Answer 41

1) Rotary/linear actuator which allows the control of the following: position, velocity, acceleration
2) The motor is coupled to a sensor for position feedback
3) Limited to 180 degrees of movement
4) Angular positioning can be controlled with a coded signal in the form of a PWM wave

Question 42

How can one get these devices to communicate with the Raspberry Pi?

Answer 42

“Straightforward” approach would be through binary words another approach would be PWM

Question 43

What is an actuator?

Answer 43

An actuator is a mechanical or electronic device within a system that receives signals from a controller and converts them into physical action or movement, enabling the system to perform a specific task or achieve a desired output.