How to Connect Two CQRobot Ocean Non-Contact Water/Liquid Level Sensors (CQRSENYW001) to Arduino UNO REV3 (A000066)?

[limeinthecoconut]

I am a complete beginner trying my hand at a home automation project.

Part of my setup includes using an Arduino UNO REV3 (A000066), and connecting two CQRobot Ocean Non-Contact Water/Liquid Level Sensors (CQRSENYW001).

There is great documentation for the sensor:

http://www.cqrobot.wiki/index.php/Non-Contact_Water/Liquid_Level_Sensor_SKU:_CQRSENYW001

And setting up one sensor is a breeze (see setup in image below):

• Red Wire to 5V
• Black Wire to GND
• Green Wire (Output) to 7

Since there is only one 5V on the Arduino (and since the project could expand), it sounds like I need to use a breadboard to allow for expansion.

I used the following video to connect the Arduino to the breadboard for power:

How to Connect Arduino to a Breadboard

See screenshot below:

Now to connect the two sensors, do I just need to put the Black and Red Dupont Wires from the sensors anywhere in the - and + columns on the breadboard and connect back to the Arduino for the output in 6 and 7?

I have noticed that doing this seems to work for the most part (there is power) for the sensor, but I just want to make sure I am doing this right. Thanks!

[gilshultz]

Connect the second the same as the first but put the output to another pin, pin 8 would be ok as would all the others except 7.

[limeinthecoconut]

@gilshultz

Okay; so here is my current setup based on your feedback. Why would 7 not work for the output in this case?

[gilshultz]

It was already in use per your statement.

[limeinthecoconut]

That makes sense! (Thank you for clarifying.)

I went ahead and moved the green output pins to 2 and 3 (since I know 0 and 1 are used for Serial communication), and here is what I have so far:

I found that the output for the second sensor fluctuates when using pinMode with INPUT (i.e., sometimes digitalRead returns LOW and other times it returns HIGH), and based on some research, it seems like I should use a pull-down resistor to help tame this behavior.

Any idea how to add a pull-down resistor in this scenario?

[gilshultz]

I cannot answer that as I do not know what the sensor is. I also need technical information on the sensor to see what the output is. If it is what I think it is use your pull-down resistor and it will quite working. I highly recommend you get a copy of the Arduino Cookbook and skim it cover to cover, then read the parts that are pertinent to your problem. At that point you will not know what your problem is but you will also understand why you are having problems.