Please help me

[niveg]

I am working on a project given to as my s4 Electrical Engineering final Design project. I have been making research for almost a week now. I have to Design and implement a measuring and control device that should operate with an existing Solar Water Heating system that has a solar absorption radiation panel, hot water tank, and a solar driven circulation pump.

the specifications of this device are as follows:

1. should provide means to measure temperatures of the Solar Hot water pane and Hot water tank
2. Adjustable temperature differential hot water pump CONTROL
3. Controller should have digital indicators for the two measured temperatures, on/off LED indicator for the pump, Indicator for the battery state - 'charged', 'charging', 'low battery voltage'.
4. Controller is to be operated from 12V battery
5. provision to charge battery from a 20V DC 10W PV panel
6. The output should be capable of controlling a 3A load
7. There should protecton against reverse connection of the PV battery charging panel
I would very much appreciate your suggestions in this regards

[Snow_Cat]

Describe your module interfaces, and the budget.

[niveg]

It is a Universty project, I am prepared to pay at most 600 south african rands. I also am not able to interconnect the sub-circuits. The sensors must read the tempratures and display them on the dispaly, compare the two temperatures, and send a signal via a trigger to control the pumps on and off. while the whole circuit is taking its supply from a 12V battery, which is connected with the LEDs to indicate the state of the battery, if its low or charged.

My problem is putting together all these things in one circuit, I dont know the exact components to use here. atleast if anyone have a hint or suggestion on how best can it be done wiithin the budget.

or hints and clues, please, help me

[Black Six]

Sounds like a little PIC controller is what you're looking for. I haven't used one in about four or five years so I can't make any recommendations. Hopefully someone else can.

[Snow_Cat]

• Inputs
  • Sensors
    • Temprature
    • Battery level
  • Trigger/Threshold levels
    • Temprature
    • Charge
  • Fault Detect?
• Processes
  • Compare/Display
  • Pump
• Outputs
  • Tempratures
  • Contion/State
  • Battery
  • Pump
  • Fault

Are there machine states? Would there be a logical condition in which you would want it not to operate normally? (ie: Not running the pumps where battery is too low?)

Can you define a ladder diagram or flowchart?