Environmental Control System Research Paper

The Development and Testing of Greenhouse Comprehensive Environment Control System Mohammed Alrefaie and Yaser Miaji .. Abstract- Greenhouses provide a convenient means to grow plants in the best environment. They achieve this by trapping heat from the sunlight and using artificial means to enhance the environment of the greenhouse. This includes controlling factors such as air flow, light intensity and amount of water among others that can have a big impact on plant growth. The aim of the greenhouse is to give maximum yield from plants possible. This report details the development and testing of greenhouse environment control system that can regulate light intensity. airflow and power supply inside the greenhouse. The details of the module

However it suffers from the problem of portability. Assembly level program can be directly translated into machine code. However, because of differences in different microcontrollers having some differences in architectures, the code written for one microcontroller may not run on another. The advantage of using a high level language like 'C' is that it is portable and the same piece of code can be simply compiled to run on different processors with the code remaining unchanged. The other advantage of using high level 'C' code is that it is easy to read and understand. However, the disadvantage of using high level language is that the code compiled is not as efficient as the assembly level program written to accomplish the same task. With the complexity of a program increasing, this difference becomes more serious for bigger more complex programs. The choice of which language to use depends on the task to be performed and to some extent about what the user is more experienced with or feels easy about.

PIC/8F452 The microcontroller that has been decided upon for this module as explained already in this report. B.LDR The device used to measure light intensity as the light sensor in this circuit is an LDR (Light Dependant Resistor). As the name shows, the resistance of this device changes with light intensity. For higher light intensity, the resistance is lower while the resistance increases as light intensity decreases. The working principle in short is that the light intensity provides energy to the electrons in the device to conduct electricity. Therefore more electrons are free to conduct electricity for higher light intensity. Since the resistance of the LDR changes with change in the light intensity, it can be put in arrangement of a voltage divider to measure its change in resistance. To do this the LDR is connected to a resistor in series. The voltage between the LDR and the resistor is the output voltage that is connected to the PIC. C. Circuit Design The circuit has been designed using two power sources. One of them powers the PIC and the BJTs with the LDR while the other powers the relay and the motor. This is because of the difference in the power ratings of the devices used in the circuit. The LDR is connected to pin 2 at port A.