Electronic Systems and Programmable Components (Core)

Question 1

How are systems designed?

Answer 1

Using a system block diagram, that shows the input, process and output (shown as blocks) of a system. They are interlinked by signals (shown as arrows).

Question 2

What is a block diagram?

Answer 2

A diagram of a system represented by blocks connected by lines/arrows. They are clear, simple and easy to read, showing all input, process and output elements that make up the system being designed.

Question 3

What are flowcharts?

Answer 3

Also known as a flow diagram, shows the step-by-step flow of an algorithm/process.

Question 4

What symbols represent which functions in a flow diagram, and what names do they have?

Answer 4

• Oval shape - Start/End
• Parallelogram - Input/Output
• Diamond - Decision
• Rectangle - Process

Question 5

What are circuit diagrams?

Answer 5

Also known as a schematic diagram, uses simplified universal symbols to represent an electronic circuit and its components, and how they are connected.

Question 6

What is an input device?

Answer 6

A device used to input data or information into a computer, allowing systems to understand chnages in the environment around them, such as a keyboard, microphone or sensors (like light-dependent resistors or thermistors).

Question 7

What is a switch?

Answer 7

A type of input, switches allow current to flow through them when the contacts inside are joined together.

Question 8

What are some examples of switch types, and what are their uses?

Answer 8

• Push-to-make/push-to-break switch - used in console controller buttons, eg fire or jump.
• Reed (magnetic) switch - used in window sensors on alarms, eg window opens and switch contacts open.
• Toggle switch - used in power switches.
• Rocker switch - used in light switches.
• Tilt switch - used to detect if something is no longer level.

Question 9

What is a light-dependent resistor (LDR)?

Answer 9

A type of resistor whose resistance changes with the light level, reducing resistance as light gets brighter. Can also be used to give an input to a circuit due to the change in the resistance.

Question 10

What is a thermistor?

Answer 10

A type of resistor whose resistance changes with temperature, typically reducing resistance as temperature increases, though some do the opposite. Used in heating systems, to check the temperature in a room and turn on a heater if it’s too cold.

Question 11

What is a pressure sensor?

Answer 11

A sensor that produces a signal that varies depending on the amount of pressure placed on them. Used in security systems, for example to see if a pressure pad has been stepped on to trigger an alarm. Some types can also be used to measure pressure in gases or liquids.

Question 12

What is a process device?

Answer 12

A device, usually an integrated circuit, that controls the process functions of a system, taking a signal from the input and acting on it by changing it in some way, eg adding a time delay, counting the number of inputs or making decisions. Programmable components like microcontrollers are typically used for this purpose.

Question 13

What is an electrical conductor/insulator?

Answer 13

A material, such as copper wire, that allows electrical current to flow through. Insulators do the opposite, preventing electrical current from flowing through, like the PVC plastic that surrounds wires to make them safe.

Question 14

What is a semi-conductor?

Answer 14

A material (eg silicon) that controls whether it is going to conduct the electrical current or prevent it - depending on how it is connected to power.

Question 15

What is a diode?

Answer 15

A semi-conductor that only allows electrical currents to flow in one direction.

Question 16

What is doping?

Answer 16

The process of adding other elements, such as boron and phosphorous, to silicon to give it the correct properties to be a semi-conductor.

Question 17

What are integrated circuits (ICs)?

Answer 17

Tiny chips that contain resistors, capacitors and transistors, which work together to complete the process they have been designed for, eg a timer, counter or microcontroller. Used in smaller products to reduce outer packaging/housing, and as they cost less.

Question 18

What are microprocessors?

Answer 18

An integrated circuit that contains all or most of the individual elements of a CPU. They are the main processor inside a computer and are designed to be programmed to perform different functions. They contain small transistors, resistors, diodes and capacitors to make up the circuit inside, meaning all the controls are in one place. Used in a lot of products, from car keys to cars, from electronic toys to mobile phones.

Question 19

What are microcontrollers?

Answer 19

A computer chip used instead of a CPU that contains a processor, memory and inputs/ouptuts, providing functionality and giving intelligence to products and systems, from mobile phones to washing machines. They are an example of a single board computer (SBC) and are manufactured as an integrated circuit (IC). They can be programmed to perform different processing functions. They come in different sizes, eg 8 pin, 14 pin and 18 pin. A widely used microcontroller example is a programmable interface controller (PIC).

Question 20

What is the key difference between microprocessors and microcontrollers?

Answer 20

Microcontrollers have memory - microprocessors do not.

Question 21

What are the advantages of microcontrollers?

Answer 21

• The size of a circuit can be significantly reduced. This is because programming replaces physical components.
• They can be reprogrammed many times. This allows changes to be made without replacing actual components.
• They have pins for connecting several input and output devices, adding to flexibility.

Question 22

What are the disadvantages of microcontrollers?

Answer 22

• They often cost more than traditional integrated circuits. They are therefore not always the best option for simple systems.
• Programming software and hardware is required. This can be expensive to buy.
• The language of the system must be learned and this adds to training costs.

Question 23

What are the different ways microcontrollers can be programmed, and what are the advantages and disadvantages of each?

Answer 23

• Text-based programming languages, such as BASIC, C++ and Python - flexible, but harder to understand and use.
• Block-based programming editors - simple to use but can be limiting if complex programs need to be written.
• Flowchart software, such as PICAXE Editor, GENIE and Yenka - simple and easy to read but there can be bugs in the system.

Question 24

How do you download a program onto a microcontroller?

Answer 24

Many systems support ‘in-circuit’ programming, meaning the microcontroller does not have to be removed from the circuit to be programmed. For some systems, the chip may have to be taken from the circuit and placed in a special downloader, using a serial or USB cable.

Question 25

What is an output device?

Answer 25

A device that takes a signal from the process device of a system and turns it back into a physical or ‘real-world’ signal, such as light or sound. Examples include car indicators, doorbell buzzers and information displays.

Question 26

How is light created as an output?

Answer 26

Created using lamps - when current flows through the filament it heats up and light is produced. Filament lamps are increasingly being replaced with energy-saving alternatives, such as light-emitting diodes (LEDs)

Question 27

How is sound created as an output?

Answer 27

Produced using buzzers or speakers.

Buzzers have an oscillator inside a plastic case. When current flows through them they produce a buzzing sound, often around 400Hz in frequency depending on the type of buzzer used. Used in doorbells and alarms.

Speakers produce sound using electromagnetism. They usually require a driver circuit to provide a signal that they can use, such as an audio amplifier. The correct speaker resistance must always be used to prevent damage to the driver circuit.

Question 28

What are open loop systems?

Answer 28

The simplest type of system, where the input sends an electrical signal to the process, and the process signals the output to respond, all in a linear fashion.

Question 29

What is a closed loop system?

Answer 29

A system that involves feedback (information used to modify performance), where a signal from the output is sent back to the input. The feedback information controls the input and provides an automated system.