Controlling stuff using computers
ADC (Analogue to Digital Converter) is needed for the computer to be able to read the data from the sensors as the data from sensor is analogue and computer can’t read analoge. (read only digital)
DAC (Digital to Analogue Converter) is needed for the applications to be able to accept the instructions from the computer. As computer send the instructions as digital but the applications can’t read digital.
The role of the sensor
INPUT: sensors take in the data of the environment around them
PROCESS: computer looks the data collected and instruct applications
OUTPUT: applications would do what computer instructed to do
Advantages of using a computer to control devices rather than people
CHEAPER: if a computer does the jobs that people needed to do, you don’t need to employ people and pay them salary
HIGHER WORK RATE:
SAFER: computers can work in an extreme conditions which are
ACCURACY:computers are less likely make mistake than people
SPEED:quicker than people doing
Examples of devices that are controlled by a computer
Computer controlled greenhouse (likely to come up in the exam)
Sensors needed to collect data:
- light sensor
- moisture sensor
- heat sensor
Control applications needed:
- grow lights to make plants flourish
- motor to turn sprinkler if plants need water
- motor to warm the greenhouse
- motor to open windows if the temperature gets too high
How the system works:
- Computer reads the data from the sensor and compare with the preset value
- Computer will instruct application to work if some data doesn’t match to the preset value. For example, if the temperature is too high, open the window. If it’s too dark, turn on the light etc,.
IGCSE ICT BLOG 