Water Flow Project

Projects General Guidance
1

This is my first Arduino project and I was surprised how easy it was to get everything up and running, but I want to make sure I didn't make a couple mistakes specifically in using the 5V pin for my flow sensor and also the flow calculations themselves.

I'm using an Arduino Uno with a WifiShield101. I'm using the following flow sensor:

I currently have the Arduino plugged in with an external voltage supply that is supplying 12V at 1A.
Per the specifications the sensor needs 5V, GND (connected directly to GND), and it has a digital output (connected directly to P2 - rising edge interrupt). I have the 5V connected directly to the 5V pin on the Arduino. However, the sensor also says the maximum current is 15mA and the Arduino documentation recommends against using the 5V pin to supply a sensor. Should I be connecting the sensor this way and do I need a resistor in line?

Additionally, the sensor says 450 pulses per liter, which works out to roughly 1700 pulses per gallon. If I only care about quantity of water usage then I just need to count the pulses and I can ignore the flow calculations in the specifications, right?

Thank you!

2

There should be no problem powering the sensor from the Arduino 5V output. The sensor will take just a few mA.

My reading of the very limited documentation suggests to count the pulses and divide by 450 to get total liters delivered.

3

Thanks for the sanity check!

4

browna3:
If I only care about quantity of water usage then I just need to count the pulses and I can ignore the flow calculations in the specifications, right?

While you might as well use the calculations they give you, I think what you say is quite reasonable. It is mainly a matter of when you want the result - now or later - and you have to do the maths eventually. You may find just getting a daily pulse count at midnight suffices.