Choosing input devices, output devices and sensors together for a system

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Quick Questions

Shade in the A or B circle for each question.

1. A supermarket checkout needs to capture the price of each item quickly. Which input device is the best fit?

A Barcode scanner

B Microphone

2. At a supermarket checkout, which is an OUTPUT device that shows the customer what they owe?

A LCD screen

B Keyboard

3. Automatic doors need to detect that a person is standing in front of them. Which sensor is the most suitable?

A pH sensor

B Infra-red or proximity sensor

4. In an automatic door system, what is the actuator?

A The motor that opens the door

B The sensor that detects the person

5. A weather station records air temperature, rainfall and wind. Where does the data come from?

A Speakers

B Sensors

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1Input: barcode scanner, keypad		AAt a supermarket checkout, these devices capture the product code and the customer's payment details
2Output: speaker, receipt printer		BThe input and output are swapped: the temperature sensor is the input that captures data and the radiator or heater actuator is the output
3An automatic door uses a sensor to detect a person, and the microprocessor then makes an actuator open the door		CAt a supermarket checkout, these devices give the beep and the printed receipt as results
4A weather station uses sensors to capture data and a screen to output the results to people		DThe devices do not suit the task: a weather station needs sensors as inputs and a screen or printer as output, not a speaker and a keyboard
5Smart home heating: Input: radiator, Output: temperature sensor		EInput: temperature, pressure, humidity sensors \| Output: LCD screen
6Weather station: Input: speaker, Output: keyboard		FInput: infra-red sensor \| Output: motor actuator

Definitions

inputs and outputs

Fill in the Blanks

Complete each line of code by filling in the missing parts.

Scenario: supermarket checkout Input: _______________ Output: receipt printer

Scenario: automatic door Sensor: infra-red sensor Output: ________ opens the door

Scenario: weather station Measures sunshine: _____ sensor Output: screen shows the readings

Scenario: smart home heating Sensor: ___________ sensor Output: heater switched on

Scenario: smart home alarm Inputs: motion sensor, keypad _______: siren, flashing light

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A INPUT code FROM scanner

B price <- LOOKUP(screen)

C OUTPUT price TO screen

D OUTPUT receipt TO printer

Question 2

A READ s FROM infra-red sensor

B IF s = movement THEN

C SEND open TO printer

D ENDIF

Question 3

A temp <- READ(temp sensor)

B hum <- READ(humidity sensor)

C OUTPUT temp, hum TO keyboard

Question 4

A lux <- READ(light sensor)

B IF lux > 20 THEN

C SWITCH lamp ON

D ENDIF

Question 5

A System: smart doorbell

B Input: button

C Input: camera

D Output: microphone

Answer Key

Choosing input devices, output devices and sensors together for a system

Section A: Quick Questions

A — Barcode scanner

A — LCD screen

B — Infra-red or proximity sensor

A — The motor that opens the door

B — Sensors

Section B: Match the Pairs

Input: barcode scanner, keypad → At a supermarket checkout, these devices capture the product code and the customer's payment details

Output: speaker, receipt printer → At a supermarket checkout, these devices give the beep and the printed receipt as results

An automatic door uses a sensor to detect a person, and the microprocessor then makes an actuator open the door → Input: infra-red sensor | Output: motor actuator

A weather station uses sensors to capture data and a screen to output the results to people → Input: temperature, pressure, humidity sensors | Output: LCD screen

Smart home heating: Input: radiator, Output: temperature sensor → The input and output are swapped: the temperature sensor is the input that captures data and the radiator or heater actuator is the output

Weather station: Input: speaker, Output: keyboard → The devices do not suit the task: a weather station needs sensors as inputs and a screen or printer as output, not a speaker and a keyboard

Section C: Definitions

inputs and outputs — A complete system uses input devices or sensors to capture data and output devices or actuators to deliver results, each chosen to suit the task.

Section D: Fill in the Blanks

Scenario: supermarket checkout
Input: barcode scanner
Output: receipt printer

Scenario: automatic door
Sensor: infra-red sensor
Output: actuator opens the door

Scenario: weather station
Measures sunshine: light sensor
Output: screen shows the readings

Scenario: smart home heating
Sensor: temperature sensor
Output: heater switched on

Scenario: smart home alarm
Inputs: motion sensor, keypad
Outputs: siren, flashing light

Section E: Spot the Error

B — The price must be looked up using the barcode data captured by the scanner. A screen is an output device and does not provide data. It should be LOOKUP(code).

C — An automatic door needs an actuator such as a motor to physically open it. A printer cannot move a door. It should be SEND open TO motor.

C — A keyboard is an input device, so it cannot show the weather readings. The results should go to an output device such as a screen.

B — The lamp should switch on when it is dark, which means the light level is low. The condition should be lux < 20, not lux > 20.

D — A microphone is an input device because it captures sound. The doorbell needs an output device such as a speaker to make the sound.