Revolution AXE102, Руководство пользователя

Страница: 1 / 38

1
PICAXE-08 ALARM PROJECT
revolution
© copyright 2002 - AXE102 Alarm Student Project Notes Version 1.1
Revolution Education Ltd. Email: info@rev-ed.co.uk Web: www.rev-ed.co.uk
1
Supported by:
A
LARM
S
YSTEMS
What is a microcontroller?
A microcontroller is often described as
a 'computer-on-a-chip'. It can be used
as an ‘electronic brain’ to control a
product, toy or machine.
The microcontroller is an integrated circuit
("chip") that contains memory (to store the program), a
processor (to process and carry out the program) and input/
output pins (to connect switches, sensors and output devices like motors).
Microcontrollers are purchased 'blank' and then programmed with a specific control
program. This program is written on a computer and then 'downloaded' into the
microcontroller chip. Once programmed the microcontroller is built into a product to
make the product more intelligent and easier to use.
Example use of a microcontroller.
Almost all modern buildings are fitted with some type of alarm. For
instance a fire detection system may have a number of smoke sensors
to detect the smoke from a fire.
However many alarm systems are also safety systems - for instance an
alarm system on an oil rig may monitor the temperature and pressure
of the crude oil as it is being extracted and automatically shut
the system down if a fault is detected. This ensures the safety of
both the workers and the environment around the oil rig.
All systems are made up of input and output devices. Often
these devices are connected to a microcontroller that interprets
the information from the sensors and switches the outputs on
and off at the correct time.
In the case of a fire alarm system the inputs may be smoke
sensors and the keypad on the front of the control panel. The
output devices are the display on the control panel as well as
the external siren and strobe light. The microcontroller is the
'brain' of the system.
Microcontrollers are powerful electronic components that have a
memory and can be programmed to switch things on and off in a
special sequence. The microcontroller in the fire alarm, for
instance, has been programmed to switcyh the siren on and off
when the smoke sensor has detected fire.
1
2
3 4
5
6 7
8
9 *
0
#
A
PICAXE
ALARM
B
C
D