Introduction: Linkit One - Water Level Controller With TV Remote Settings

I already done a water level controller and posted here see the link Accurate Liquid level Controller with low cost sensor and TV remote for settings. Now its works fine and i use it online. Now change it to Linkit one to learn what are the difference in both controllers with hard ware and software.

Step 1: Materials and Tools Required

Materials required to make a new one

Electronics Parts

1) Link it one board.

2) Plain pcb.

3) 16 X 2 LCD display (I use serial LCD display it only needed 3 wires)

4) Output relay board.

5) IR sensor for remote settings.

6) Multiple rotation potentiometer(i use 5 rotation 47k potentiometer).

7) Wires.

Mechanical Parts

1) Pipe for fix the sensor.

2) Wheel.

3) Strong thread or String

4) Counter weight.

5) Ball or thermocol (for floating)

Tools needed

1) Soldering iron, lead and paste.

2) Screw drivers.

3) Spanners.

4) Hacksaw blade.

Materials required to change the old one

Electronics Parts

1) Link it one board.

2) 5V relay control board.

Tools needed

1) Soldering iron, lead and paste.

2) Pcb soldering male header

For new Project please refer my previous link and do the sensor as per the link Accurate Liquid level Controller with low cost sensor and TV remote for settings.

Step 2: Disassemble the Old One

1) Open the box.

2) Remove the board fitted with arduino.

3) Now the circuit is ready to fitted with Linkit one but, can't able to fit it directly with Linitit done. Due to Arduino is worked under avr and linkit one is work under mtk. So changes want to done in circuit and program to run.

Step 3: Changes in Circuit

1) For lcd display data pin is taken from pin2 in arduino it is move to pin 1 in Link it one

2) For IR sensor Pin 11 is used for arduino it is move to pin 1 in Link it one

3) 12V relay module is changed to 5 V relay module for Link it one.

Reason for the changes are follow in the next steps.

Step 4: Soldering in Digital Side

As per the changes diagram. In previous circuit

1) Digital pin 0 and 1 are not fitted. So two new male header fixed.

2) Remove the lcd data cable from Pin 2 and soldered in pin 1

3) Like wise remove the LDR wire from pin 4 and soldered into pin 2.

Step 5: Soldering in Analog Side

1) First change the 12V relay control board to 5 V relay control board.

2) In Arduino the power supply for relay control is taken from vin pin. Remove the wire and soldered in 5V supply in link it one.

3) Already sensor is fitted in A0 so no changes needed.

Step 6: Fit the Circuit on Board

1) Correct the pins and fit the circuit over the board.

2) Now the hard ware part is ready.

Step 7: Coding Changes

The header files said the difference in programming.

1) Softwareserial library not supported in Linkit one.

2) EEPROM library not supported in Linkit one.

3) IRremote.h not supported in Linkit one


Software serial library not work in linkit one. So the LCD display connected to digital pin 1 (TX) of serial1. So change myserial variable as serial1 all places.


EERPOM library is not working in Linit one. But alternate LEEPROM library is supplied with the Linkit one. Just change the header file all is done dont want to change the program.


Download IR_Recv_LinkIt from the location given. Paste the library file in C:\Program Files\Arduino\hardware\arduino\mtk\libraries. Due to default pin for the IR receiver is Data pin 2. Connect the Ir receiver to Data pin 2. Changes want to done in variable declaration of the buttons for Enter, Set, Up, Down, Escape. Also change coding for Value fetch from the sensor. Because the function various for IRremote.h and IR_Recv_LinkIt.h.

Just copy the code and upload to ur link it one board.

Step 8: Testing

1) After complete the program and upload. By pull and push the thread in the sensor and make the potentiometer rotate.

2) see the reading changes in the display show the percentage of water in tank.

3) When Reading is below the set point u notice that the relay turns on.

4) when Reading is above the set point u notice that the relay turns OFF.

Step 9: Calibration and Setpoint Video

See how calibration is done. First set the zero calibration with Water tank empty. Then Press enter and fill the tank for Full Calibration. Now the calibration finished.

Change set point. Use setup to enter change set point. MI means minimum set point. MA means maximum set point. Change the value using volume key. Press the set point to change. when water level reach minimum set point relay on and switch on the pump. When water level reached maximum set point the relay off and switch off the pump.

Step 10: Linkit One - Water Level Controller Running

Now check the instrument with the sensor fitted in the tank and found all ok.

Step 11: Re-assemble in the Box

Now fit the whole thing in the box with display and IR receiver in the front side of the box. and use a USB power adapter to power it in the fixed location.

Want to do more with the same water level controller with reduced cost. Work in progress post after complete.

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