Conductive liquid sensing system

1. A method of detecting a conductive liquid with electrodes of a circuit disposed in the conductive liquid, the method comprising the steps of:

applying a first digital high at a first digital output of a microprocessor;

wherein the first digital high is connected to a first electrode by a first switch;

measuring a first voltage at a first analog input of the microprocessor,

wherein the first analog input is connected to a second electrode by a second switch;

applying a first digital low at the first digital output;

measuring a second voltage at the first analog input;

determining a first final voltage by calculating a difference between the first voltage and the second voltage;

switching the first switch to connect a second analog input to the first electrode;

switching the second switch to connect a second digital output to the second electrode;

applying a second digital high at the second digital output;

measuring a third voltage at the second analog input;

applying a second digital low at the second digital output;

measuring a fourth voltage at the second analog input;

determining a second final voltage by calculating a difference between the third voltage measurement and the fourth voltage measurement; and

determining a final voltage by averaging the first final voltage and the second final voltage,

wherein the final voltage is indicative of the first electrode and the second electrode contacting the conductive liquid.

2. The method of claim 1 ,

wherein the first digital high and the second digital high have a signal strength of between four volts and six volts, and

wherein the first digital low has a signal strength between zero volts and one volt.

3. The method of claim 1 ,

wherein the first switch and the second switch are double pole single throw switches, and

wherein a signal to switch is received from the microprocessor.

4. The method of claim 1 ,

wherein the final voltage is further indicative of a resistance from at least one resistor, and

wherein the at least one resistor has a resistance of one Mega-Ohm.

5. The method of claim 1 ,

wherein the calculation of the first final voltage eliminates asymmetry effect from the first final voltage, and

wherein the calculation of the second final voltage eliminates asymmetry effect from the second final voltage.

6. The method of claim 1 , wherein a frequency of switching the first switch and the second switch is based at least in part on an electrolysis between the first electrode and the second electrode.

7. The method of claim 1 , further comprising the step of determining the resistance of the conductive liquid, wherein an analog to digital converter converts an input from analog to digital.

8. The method of claim 7 , further comprising the step of sending a signal from the processor to a valve for controlling a level of the conductive liquid, wherein the control of the valve is based at least in part on the final voltage.

9. The method of claim 1 , further comprising the step of filtering a first input at the first analog input and a second input at the second analog input with a low pass filter to reduce noise.

10. The method of claim 1 , further configured with a plurality of electrodes physically connected to the microprocessor by a plurality of switches.

11. A system of detecting a conductive liquid using electrodes in contact with the conductive liquid comprising:

a circuit for transmitting electrical signals between a output and an input, the circuit comprising:

a first electrode and a second electrode separately disposed in the conductive liquid; and

a microprocessor including a digital output selectively attached to the first electrode and an analog input selectively attached to the second electrode,

wherein a digital high is applied at the first digital output,

wherein a digital low is applied at the first digital output; and

one or more non-transitory computer-readable media storing computer-executable instructions that, when executed by a processor, perform a method of detecting the conductive liquid, the method comprising the steps of:

measuring a first voltage at the analog input when the digital high is applied at the digital output;

measuring a second voltage at the analog input when the digital low is applied at the digital output;

determining a first final voltage by calculating a difference between the first voltage and the second voltage,

wherein the first final voltage is indicative of the first electrode and the second electrode in contact with the conductive liquid.

12. The system of claim 11 ,

wherein the digital output is a first digital output and the analog input is a first analog input; and

further comprising a second digital output selectively attached to the second electrode and a second analog input selectively attached to the first electrode,

wherein the digital high is applied at the second digital output;

wherein the digital low is applied at the second digital output; and

wherein the media is further executable to perform the steps of:

measuring a third voltage at the second analog input when the digital high is applied at the second digital input;

measuring a fourth voltage at the second analog input when the digital low is applied at the second digital input;

determining a second final voltage by calculating a difference between the third voltage and the fourth voltage; and

determining a final voltage by averaging the first final voltage and the second final voltage.

13. The system of claim 12 ,

wherein the digital high has a signal strength of between four volts and six volts,

wherein the conductive liquid is water,

wherein the first electrode is switched from the first digital output to the second analog input by a double pole single throw switch, and

wherein a signal to switch is sent by the microprocessor.

14. The system of claim 11 , wherein the media is further executable to perform the step of subtracting the first final voltage from the second final voltage to eliminate asymmetry effects and common-mode noise.

15. The system of claim 11 , further comprising a valve for controlling a level of the conductive liquid,

wherein the valve is actuated by a signal sent by the processor, and

wherein the control of the valve is based at least in part on the final voltage.

16. The system of claim 11 , further comprising an analog to digital converter,

wherein the analog to digital converter converts an input from analog to digital, and

wherein the media is further executable to determine a resistance of the conductive liquid from the digital input.

17. A method of detecting a conductive liquid with electrodes of a circuit disposed in the conductive liquid, the method comprising the steps of:

applying a first electrical power at a first digital output connected to a first electrode by a first switch;

measuring a first voltage at a first analog input connected to a second electrode by a second switch;

applying a second electrical power at the first digital output;

measuring a second voltage at the first analog input;

applying the first electrical power at a second digital output connected to the second electrode by the second switch;

measuring a third voltage at a second analog input connected to the first electrode by the first switch;

applying the second electrical power at the second digital output;

measuring a fourth voltage at the second analog input;

determining a first final voltage by calculating a difference between the first voltage and the second voltage,

wherein calculating the difference between the first voltage and the second voltage cancels a first asymmetry effect between the first electrode and the second electrode;

determining a second final voltage by calculating a difference between the third voltage and the fourth voltage,

wherein calculating the difference between the third voltage and the fourth voltage cancels a second asymmetry effect between the first electrode and the second electrode; and

determining a final voltage by averaging the first final voltage and the second final voltage.

18. The method of claim 17 ,

wherein the first electrical power is a digital high between four volts and six volts, and

wherein the second electrical power is a digital low between zero volts and one volt.

19. The method of claim 17 ,

wherein the first switch and the second switch are double pole single throw switches, and

wherein a signal to actuate the switches is sent by the microprocessor.

20. The method of claim 19 , wherein a frequency of switching is based at least in part on an electrolysis between the first electrode and the second electrode.