Arduino Fuel Consumption Tracker with YF-S201 Flow Sensor

Projects General Guidance
1

Hi Arduino community,

I’m building a fuel consumption tracker using an Arduino Nano and a YF-S201 flow sensor to measure real-time fuel usage for a car project. It calculates liters per 100 km, displays it on a 16x2 LCD for eco-driving, and logs data to an SD card for trip analysis.

Here’s a basic sketch to read the flow sensor and show fuel usage:

// Fuel Consumption Tracker
#include <LiquidCrystal.h>
#define FLOW_SENSOR_PIN 2
LiquidCrystal lcd(12, 11, 5, 4, 3, 6);
volatile int flowPulses = 0;
float litersPerPulse = 0.0001; // YF-S201 calibration
unsigned long lastTime = 0;

void countPulses() {
  flowPulses++;
}

void setup() {
  Serial.begin(9600);
  lcd.begin(16, 2);
  pinMode(FLOW_SENSOR_PIN, INPUT);
  attachInterrupt(digitalPinToInterrupt(FLOW_SENSOR_PIN), countPulses, RISING);
  lcd.print("Fuel Tracker");
}

void loop() {
  unsigned long currentTime = millis();
  if (currentTime - lastTime >= 1000) {
    float liters = flowPulses * litersPerPulse;
    float lPer100km = liters > 0 ? (liters * 1000) / 10 : 0; // Simplified
    lcd.setCursor(0, 1);
    lcd.print("L/100km: ");
    lcd.print(lPer100km);
    Serial.println(liters);
    flowPulses = 0;
    lastTime = currentTime;
  }
}

To calibrate the sensor, I’ve been using a fuel calculator at kalkulatorpaliwa.com.pl to cross-check readings against trip distances, which has been really helpful. A few questions:

  1. How do you filter noise in flow sensor readings? I’m getting occasional pulse spikes.

  2. Has anyone integrated a GPS module (like NEO-6M) for precise distance tracking?

  3. What’s the best SD card logging format for long-term data to avoid filling it?

I’d love feedback from anyone who’s worked on similar projects. Any ideas for adding a real-time eco-driving score display?

Thanks!

2

It depends on the sensor. Please post the datasheet.
What kind of noise are You talking about?

Yes.

Please define good, better, the best!

A single board micro computer was built 35 years ago and it was used during 10 years. It showed speed and fuel data.

3

This is not the way to read "flowPulses" when an interrupt is involved.

4

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  2. Analog Devices: Automotive Electronics Design:
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These resources should provide a start for a strong foundation for anyone involved in automotive electronics design. If you need further help or more resources, feel free to ask!

5

As @Railroader says, that is not a safe way to read the variable that's updated by the interrupt function.

Change it like this:

  if (currentTime - lastTime >= 1000) {
    int flowPulsesNow;
    noInterrupts();
    flowPulsesNow = flowPulses;
    flowPulses = 0;
    interrupts();
    float liters = flowPulsesNow * litersPerPulse;
    float lPer100km = liters > 0 ? (liters * 1000) / 10 : 0; // Simplified
    lcd.setCursor(0, 1);
    lcd.print("L/100km: ");
    lcd.print(lPer100km);
    Serial.println(liters);
    lastTime = currentTime;

Even if this does not appear to fix your problem, keep this change.

6

There are many types of Nano these days, with different designs and capabilities, so please be more precise.