41081 Chapter 1: Sensing Actuation and Control
Chapter 1 - Intro to Embedded Systems
What is an Embedded System?
• An embedded system is a computer system embedded into another device
• They must react quickly to changing inputs and generate new outputs in response.
• Most systems that operate on electricity and do something intelligent have
embedded systems.
o Clothes washing machine, motion sensing lamp, microwave
o Cruise control, navigation system, pacemaker
• Microprocessors are implemented on integrated circuits. These circuits have been
doubling i trasistor apait eer 8 oths aordig to Moores La
o This doubling means that systems can be made smaller, enabling new
inventions such as ingestible computerised pills.
Basic Components
• A bits changing value over time is called a digital signal (with digital referring to the
use of discrete rather than continuous values).
• A switch is a component with a single bit output that is either 0 or 1 depending on
whether the switch is in the on or off position.
o Off → 0
o On → 1
• When not in a digital system design, a switch is an electromechanical component
with a pair of electrical contacts. These contacts are in one of two mechanically
controlled states; open, closed.
• A push button operates similarly, however a push button enters a closed state when
pressed. The moment the force is removed, the push button reverts to and stays in
an open state. An abstraction of this is a component with a single bit output that is 0
when not pressed and 1 when pressed.
• A light emitting diode is a semi conductor with a pair of contacts. When electrical
current is applied, the LED illuminates. An abstraction of this is a component with a
sigle it iput, that he is , doest illuiate.
• A component that can execute some computing functionality is a key part of an
embedded system.
• A microcontroller is a programmable component that reads digital inputs and writes
digital outputs according to an internally stored program. It contains an internal
program memory that stores machine code generated from compilers.
• The switch and buttons are examples of sensors which convert physical phenomena
into digital inputs to the embedded system.
• The LED is an example of an actuator which converts digital outputs into physical
phenomena.
RIMS
• RIMS (Riverside-Irvine Microcontroller Simulator) is a graphical web based tool.
• In a RIMS debugger, pressing break temporarily stops the program execution and
highlights the next statement to execute.
• Pressig step i a deugger eeutes the urret highlighted C stateet the
highlights the next statement.
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