retemp : remotetemperaturecontroller group members: kenny chung chung wai [email protected] amish...
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ReTemp: REMOTETEMPERATURECONTROLLERGroup Members:
Kenny Chung Chung Wai
Amish [email protected]
Instructor: Dr. Roy Czernikowski
Description:
Hardware Interface:
User Interface:
RIT Computer Engineering Senior Design Project Fall 2004
Software:
Retemp allows an individual to control the temperature of a house or a room. The internet is used as a medium to permit a user to remotely change the current temperature of a building as well as observe the current indoor and outdoor temperature.
The heating and cooling devices are controlled by the Motorola 68HC12 micro-controller, which communicates with the PC using an RS-232 cable.
Hardware Schematics:
Characteristic of Thermistor 271-110
y = 0.0467x + 1.3267
R2 = 0.9999
0
0.5
1
1.5
2
2.5
3
3.5
0 5 10 15 20 25 30 35 40
Temperature (deg C)
Ou
tpu
t V
olt
age
(V)
Heating System
Cooling System
Sensing System
Cost Analysis:
Java Interface
HC12 Micro-controller
Lamp control state
The login page of the user interface is accessed at http://retemp.rh.rit.edu. After the proper username and password have been validated, the temperature controller is displayed. It consists of 2 parts:
• Main controller: The user can adjust the current indoor temperature in degree Celsius or Fahrenheit
• Scheduler: The scheduler window is opened using the Open Temperature Scheduler button. This allows the user to set two different schedule as well as clear any schedule previously set.
Equal state Fan control stateIf the wanted
temperature is higher than the current temperature, the lamp will increase the temperature until the wanted temperature plus one degree is reached. The lamp will then turn off and let the cold seep in cooling the temperature to the wanted level.
If the wanted temperature is lower than the current temperature, the fan will decrease the temperature until the wanted temperature plus one degree is reached and then turn off to allow the cold to seep in cooling the temperature to the wanted level.
This is shown in figure 1
If the wanted temperature is higher than the current temperature, the lamp will increase the temperature until the wanted temperature minus one degree is reached. The lamp will then turn off and let the heat seep in heating the temperature to the wanted level.
If the wanted temperature is lower than the current temperature, the fan will decrease the temperature until the wanted temperature plus one degree is reached and then turn off to allow the cold to seep in cooling the temperature to the wanted level.
This is shown in figure 2
If the wanted temperature is higher than the current temperature, the lamp will increase the temperature until the wanted temperature minus one degree is reached. The lamp will then turn off and let the heat seep in heating the temperature to the wanted level.
If the wanted temperature is lower than the current temperature, the fan will decrease the temperature until the wanted temperature minus one degree is reached and then turn off to allow the heat to seep in heating the temperature to the wanted level.
This is shown in figure 3
Wanted temperatu
re
Wanted temperatu
re plus one
Wanted temperature minus
one
Test lower limit
Turn off lamp and fans
Test Higher limit
Turn on lamp
Turn on fans
Wanted temperatu
re
Wanted temperatu
re plus one
Wanted temperature minus 1
Turn off lamp and fans
Turn off lamp and fans
Turn on fans
Turn on lamp
Wanted temperatu
re
Wanted temperatu
re plus one
Wanted temperature minus
one
Test lower limit
Turn on fans
Test Higher limit
Turn off lamp and fans
Turn on lamp
Figure 1: Lamp control state
Figure 2: Equal control state
Figure 3: Fan control state
Main Items Market Value ($) Our Cost ($)
M68HC12 Micro-Controller 150.00 0.00
Server(PC) 500.00 0.00Thermistor 271-110 7.50 7.50Solid State Relay RS1 11.99 11.99Fan 11.90 0.00Wood board 6.00 0.00Plexiglass 9.00 9.00Light Bulb 0.50 0.00Misc. 20.00 20.00
Total 716.89 48.49
The heating system consists of a light bulb triggered by the Port 0 through the Solid State Relay
The cooling system consists of two fans, one extracting the hot air and one blowing cold air in.
The sensing system consists of three linear thermistors: two are placed indoor to measure the average temperature, one is placed outdoor to measure the outside temperature.