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Thread: water level controller

  1. #1

    Default water level controller

    guys i wanted to use my mega16 in sleep mode.so i got an idea of making a water tank level controller.
    in this i am using two level indications.one at the top and one at the bottom.
    the transition from high to low signal on the lower level indicator (no water at bottom to conduct signal) generates an interrupt through INT0.
    through the corresponding isr it turns on the bit controlling the pump

    the transition from low to high on the high level indicator(tank full) generates an interrupt through INT1 .through the corresponding isr it turns off the bit controlling the pump.

    1)But the problem here is I am not sure whether wen no water is present at a particular pin(floating).will it indicate a zero to my avr or not.

    2)and also the avrstudio isn't simulating it properly.it stops in between.
    3)is the sleep command that i have added valid?

    Code:
    //overhead tank water level controller
    //d2 output for relay to the pump
    //INT0 low level interrupt
    //INT1 high level interrupt
    
    #include<avr/io.h>
    #include<avr/interrupt.h>
    #include<avr/sleep.h>
     
     
    ISR(INT0_vect)
       {
          PORTD|=(1<<0); //make pin high
    	  
    	  
        } 
     
    ISR(INT1_vect)
       {
         PORTD &=~(1<<0); //make pin low
    	 
    	
    	}
     
    int main(void)
     {
      
      DDRD|=(1<<0);
      
      MCUCR|=(1<<SE);                        //enabling sleep mode
      
      MCUCR|=(1<<SM0) | (1<<SM1) | (1<<SM2); //selecting idle mode
      
      MCUCR|=(1<<ISC01);                    //falling edge interrupt sense on INT0
      
      MCUCR|=(1<<ISC11)|(1<<ISC10);       //rising edge interrupt sense on INT1
      
      GICR|=(1<<INT0)|(1<<INT1);          //interrupt enable
      
      sei();                              //enable global interrupt
      
      for( ;;)
        {
          void sleep();
        }
     }
    8)

    please dont blame me for this
    does anyone know why the avrfreaks.net site is down since yesterday? :?

  2. #2
    Senior Member Cyborg
    Join Date
    Jan 2006
    Location
    hyderabad
    Posts
    170

    Default

    sorry not related to ur question but,

    i was also planning to build one level controller and indicator for my overhead tank.i did some search and found this circuit.
    http://www.electrofriends.com/projects/water/index.html

    i liked it bcz,it has both manual and auto modes.but the only problem is with the sensors.i don' recommend placing metallic probes for detecting water level.they will corrode.so planning for some fool proof system.
    I am reactive.

  3. #3
    Senior Member T-1000
    Join Date
    Oct 2006
    Location
    Agra, India
    Posts
    406

    Default

    Firoz, the corrosion happens because of electrolysis. Water in tanks will be an ionic conductor. The two probes that you would dip into the water will act as electrodes.

    What you can do is apply an AC signal (at say, 12V) to one of the electrodes, while using the other electrode to detect the signal. This way the electrolysis is vastly reduced. Frequency of the signal should be about 1kHz or more, for this scheme to prevent corrosion. A square waveform generator can be made by a simple op-amp, a ceramic capacitor and some resistances. Of course, you'll need a dual supply for the generator to alternate between + and -. Ask me if you have further questions.

    There are other schemes for liquid level detection that use capacitance change between the electrodes (water acts as the dielectric). You could check these as well.
    --
    Mohit Mahajan,
    www.BioZen.co.in

  4. #4
    Senior Member Cyborg
    Join Date
    Jan 2006
    Location
    hyderabad
    Posts
    170

    Default

    thanks for the explanation.
    i had some more ideas in my mind like read relay sensor,using some sort of floating magnet method in side a PVC pipe.i still have to work on it.
    I am reactive.

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