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Automated Pool Maintenance System


Pool pump is replaced with a small circulation pump. Heating system is ... One sensor placed at the pump output. One sensor placed at the other side of the pool ... – PowerPoint PPT presentation

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Title: Automated Pool Maintenance System

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 customers PC inside the home
  • Allows for multiple temperature settings to be
    entered for different time periods

Project Description
  • Modeling a Pool
  • Pool is replaced with a 20 gallon fish tank
  • Pool pump is replaced with a small circulation
  • 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
  • One screen to schedule different temperature

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 1?C when heated
  • The resolution of the temperature sensor is 0.07
    C with a range between -15 C and 100C

Project Components
  • Fish Tank
  • 2 Temperature Sensors
  • 1 pH Sensor
  • Hot Plate
  • Acid/Base/Water Pumps
  • Windows PC
  • HC12 uController
  • Wireless Modems

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

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 users settings
  • Must control the hot plate and pumps to satisfy
    the users 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

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
  • Software is built using Java

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