Phantom pulses of the flow meter.

Hello!

In the project I use an Arduino UNO and the following peripherals:
RFID plate[/ b], relay[/ b] for solenoid valve actuation and flowmeter[/ b].
Basically, it is a self-service beverage system where sporadically, the values ​​sent by the flowmeter "fire" as if the customer were serving, but without even dropping a drop.
The operation is:
>> The customer has acquired an RFID card and adds credits that are linked to the TAG of the card;
>> Pass the card at the station (for serve yourself). When it is recognized, the valve opens and the customer can dose through the tap how much he wants to take, the value is totaled on the display of the tablet and shot on the card.
>> The customer stops serving himself and the system counts a time and logs out of the account.
There are situations where before even tapping the tap for the flow to occur, the system appears as if the customer has already served.
I do not know what it can be, I checked the arduino's power.
There are times when it varies, but it does not fall below 4.99V and the maximum I observed it was 5.26V. The board is being powered by a typical cell phone (5V and 1.5A), actually originating from the tablet that is also powered. That is part of the station set (product).
Can the Arduino be experiencing any kind of electromagnetic interference in which it "loses" in the loop?
The strange thing is that it happens in some specific seasons and in some moments, there is no pattern.

Did your plumber include a check valve to stop reverse flow?

Paul

Can the Arduino be experiencing any kind of electromagnetic interference in which it "loses" in the loop?

It can be. But it's not very likely if the hardware is done right. You didn't provide any information about it. Post your code, post a list of the used hardware (including links) and a wiring diagram (that also shows the wire lengths).

Could also be the result of a floating pin (or, in case of long wires, insufficient filtering or a too weak pull-up).

Same post in the Portuguese forum, so we may never hear from the OP again.

Paul

Doesn't that happen all the time?