Automated Pool Maintenance System Jonathan Arbogast Janine Garnham Ajay Suthar.
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Transcript of Automated Pool Maintenance System Jonathan Arbogast Janine Garnham Ajay Suthar.
Automated Pool Maintenance System
Jonathan Arbogast
Janine Garnham
Ajay Suthar
Project Description
Monitors and controls pH and temperature of a swimming pool
Wireless control from a graphical interface on the customer’s PC inside the home
Allows for multiple temperature settings to be entered for different time periods
Home PCRS-232 CableRS-232 Cable
Embedded Controller
Communication Path fromHome PC to the Embedded
Controller
Wireless Modem Wireless Modem
Project Description
Modeling a Pool– Pool is replaced with
a 20 gallon fish tank– Pool pump is
replaced with a small circulation pump
– Heating system is replaced with a hot plate
User Interface
Two screens are available for the user– One main screen for
monitoring and entering new settings
– One screen to schedule different temperature settings
pH Specifications
Recommended pH levels for a pool are 7.2 to 7.8
The system will be able to control the pH level to within ±0.1 pH units
The pH sensor has a sensitivity of 0.02 pH units
Temperature Specifications
The accuracy of the monitored and controlled temperature will be within ±1C when heated
The resolution of the temperature sensor is 0.07 °C with a range between -15 °C and 100°C
Project Components
Fish Tank 2 Temperature
Sensors 1 pH Sensor Hot Plate Acid/Base/Water
Pumps Windows PC HC12 uController Wireless Modems
Temperature
Sensor
Pump
Hot Plate
Component Placement Around the Pool
HC12Controller
Alkaline AdderAcid Adder
pH
Sensor
Temperature
Sensor
Internal Operation
Interface to Sensors/Pumps/Hot Plate HC12 Processing Serial Protocol Wireless Conversion User Inputs
Interfacing to the Sensors
pH sensor has one DC output– Linearly related to the pH level– 1.75V at a pH of 7– 0.25V/pH level change
Temperature sensor has one DC output– Varies linearly with respect to temperature
These voltage levels will be connected to three ADC ports on the HC12
Placement of Temperature Sensors
One sensor placed at the pump output One sensor placed at the other side of the pool Running average will be used
Interfacing to the Pumps
Using simple windshield washer pumps
– Controlled by a 12V signal– Circuit based on a
Darlington Pair will be used to convert the 5V output from the HC12 to a 12V signal with enough drive capability
0
From HC12U 1 A
7 4 3 7
1
23
12
1 2 V
R 1
1 5 0
WasherPump
Q 12 N 2 7 8 5
3
2
14
12
5 V
Interfacing to the Hot Plate
Hot Plate Interface– Crydom AC Relay– Controlled by a 1.6mA 5V signal– Can drive 12A at 120V AC on the output side
HC12 Processing
Must respond to several interrupt sources
– pH Sensor– Temperature Sensors
Must make decisions based on the user’s settings
Must control the hot plate and pumps to satisfy the user’s settings
Serial Protocol
We will use a higher level protocol to check for errors and recover from them
– Uses set start and stop bytes for all messages
– All messages include a checksum
– All messages are either ACKed or NACKed
Serial PortInitialization
Look for StartCharacter (X)
Look for StopCharacter (Y)
Check theChecksum
Send NAK(XNY)
Parse theCommand
Send ACK(XOY)
Wireless Conversion
Conversion to wireless signals is handled by MaxStream modems
Buffering at both the input and output side Translation between RS232 and 5V CMOS is
handled by converter board.
User Inputs
Windows software converts user actions into serial messages
Sent over wireless modem to the HC12 for processing
Software is built using Java
T - Get the current temperatureP - Get the current pH level
S - Set the desired temperatureC - Set the desired pH level
Wireless Demo
Small demo of the wireless communications Modems are setup in a loopback
configuration
System Verification
A “second opinion” must be used to demonstrate that the specs have been met– Temperature checked with a digital thermometer– pH checked with a separate digital pH meter
Future Enhancements
Base/Acid/Water Level Sensors Chlorine Sensors & Dispensers
– Not included due to expense
Adjusting for different pool sizes– Would change the amount of acid/base to add– Would change the temperature response times
Questions??