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Microcontrollers

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A2

 a

System on a Chip

A family of integrated circuits that contain all the sub-systems needed to make programmable control systems on a single chip.

Compare this with a traditional PC where multiple chips and subsystems are needed. Smart-phones and tablet PCs use many techniques "borrowed" from microcontrollers and are working towards one-chip designs.

Von Neumann Architecture

Processors based on the Von Neumann architecture have three buses.

 b

Harvard Architecture

These chips have an extra instruction bus. This allows instructions to be fetched at the same time as data. This makes processing faster. This is known as the Harvard Architecture.

Microcontroller Architecture

Fetch Execute Cycle

Step

Von Neumann - Slower

Harvard - Faster

1 Fetch Instruction Fetch Instruction and Data
2 Fetch Data Execute Instruction
3 Execute Instruction Add 1 to the Program Counter
4 Add 1 to the Program Counter Fetch the next instruction and data.
The Harvard chip gets more done
per clock cycle.
 c

Microcontrollers

 d

Benefit to Society

 e

Inside Microcontrollers

The diagram above shows most of the features of a microcontroller.

 f

Processor

 g

Clock

 h

Memory (ROM, RAM, Flash)

 i

Input/Output Ports

 j

Von Neumann Architecture

 k

Three Buses

 l

Harvard Architecture

 m

Four Buses

 n

Bus Widths - 2N

The bus width is important. This is a 2n calculation. You can calculate ...

 o

Hardware and Software

 p

Hardware

 q

Software

 r

Firmware

 s

Wetware

 t

Extreme Performance - Thanks XKCD

Abstraction.png

 

 

 

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