Fuelmanager : 8 Steps (with Pictures)

Fuelmanager is an integrated system that gives car owners more insights about their fuel consumption and fuel costs.

By installing a simple plug and play module and connecting it to your smartphone, you wil see lots of information about your fuel usage, fuel costs and even an overview of all recent routes you have driven.

Being based on an ESP32, Raspberry Pi 4 and an OBD2 bluetooth reader makes Fuelmanager cheap and easy to recreate and use.

Optionally you can use a HDMI Screen to see some real-time data while driving on the road.

In September 2020 I started at Howest Kortrijk in Belgium, there my Bachelors Degree adventure started. At the end of the 2nd semester we needed to implement everything we had learned so far in a 'project'. Because I really like cars and everything about them I started looking into projects with cars.

This is how Fuelmanager was born.

Supplies

Raspberry Pi 4 (Min 4GB Ram)
Micro SD Card (64GB Recommended)
USB-C Car Charger
12v - 5V Buck converter (1A)
OBD2 ELM327 Bluetooth Module
HDMI LCD Display
ESP32 DevKit Module
HDMI Cable
5V Rotary Encoder
WS218B RGB Led Strip
NEO - N8M GPS Module
Jumper Wiring

Step 1: Step 1 : Circuit and Components

This is the Circuit as it is currently configured in my software. As you see it is not that hard to replicate, the magic is in the software so all you need to do is connect the components like illustrated above.

Step 2: Setting Up Raspberry Pi 4 and Packages

1. Install the OS

Download Raspberry Pi Imager from https://www.raspberrypi.org/software/

And Flash Raspberry Pi OS with desktop and recommended software

2. Configure boot files on SD Card

When the flashing is finished, take your SD Card out of your PC and reinsert it.
You should see a disk named 'Boot' pop up in the disks folder of your PC, go ahead and open it
Create an empty filed with no extension named 'ssh' to enable ssh functionality on the Raspberry Pi
Locate and open the file cmdline.txt and add 'ip=169.254.10.1' at the end so we can connect later

3. Boot your Raspberry Pi

Insert the SD card in the Raspberry Pi
Connect your PC and the Raspberry Pi directly with an Ethernet cable
Plug in the power supply of the Raspberry Pi
Open a CMD or Terminal window and type 'ssh pi@169.254.10.1'
The password is the default one: 'raspberry'

4. Configure Raspberry Pi OS

With 'sudo raspi-config' choose option 3 -> Serial Port -> No -> Yes
Choose option 5 and set your country, this is important for the wifi network we will create.

5. Configure Hostapd wireless acces point

Follow the tutorial on the Raspberry Pi site HERE but you can skip the Bridge part as we wont have internet access.

6. Install Database Server

sudo apt install mariadb-server mariadb-client
sudo mysql_secure_installation
sudo mysql
create user student@localhost identified by 'W8w00rd';
flush privileges: 'grant all privileges on *.* to username@localhost;'
flush privileges;
exit;

7. Install RGB Led drivers if you want to use them

curl -L http://coreelec.io/33 | bash

Step 3: Cloning Software

Clone the code from this GitHub Repo HERE

You will see 3 folders named: Backend, Frontend , Database

Now we need to set up a few more things:

Go in the folder Backend and run this command:
- pip3 -r install requirements
Go in the folder Databse and run this command:
- mysql -u student -p W8w00rd Fuelmanager.sql
Go in the folder Frontend and execute following commands:
- sudo -i
- sudo apt install apache2
- sudo nano /etc/apache2/sites-available/000-default.conf
- Change 'DocumentRoot' to 'DocumentRoot/frontend'
- Save by CTRL+X and Y
- service apache2 restart

Step 4: Setting Up ESP32 and OBD2

For this step you will need the OBD2 Bluetooth Module and the ESP32.

The Software should work with any of the Bluetooth OBD2 modules you can find that are based on an ELM327. In the software.

The script automatically connects to the WiFi network that the Raspberry Pi 4 creates so it can Post all the data to our backend.

You can find the code below.

!IMPORTANT! Because we use both Bluetooth and WiFi, the software exceeds the limits of the on-board flash storage of the ESP32, we can fix this by changing our partition scheme:

in Arduino go to Tools -> Board -> Pick ESP32 Dev Module then go to

Tools -> Partition Scheme -> Pick Minimal Spiffs

If you have trouble connecting, try changing the "OBDII" parameter in ELM_PORT.connect("OBDII") to the mac address of the OBD2 Module, you can find that if you scan your bluetooth devices with a Smartphone.

Fuelmanager_OBD.ino

#include"BluetoothSerial.h"
#include"ELMduino.h"
#include<ArduinoJson.h>
#include<HTTPClient.h>
#include<WiFi.h>
constchar *ssid = "Fuelmanager";
constchar *password = "Fuelmanager123";
String serverName = "http://192.168.0.10:5000/api/postobd";
BluetoothSerial SerialBT;
#defineELM_PORT SerialBT
ELM327 myELM327;
voidsetup()
{
  WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED)
  {
delay(500);
  }
  ELM_PORT.begin("Fuelmanager", true);
while (!ELM_PORT.connect("OBDII"))
  {
delay(500);
  }
while (!myELM327.begin(ELM_PORT, true, 2000))
  {
delay(500);
  }
delay(1000);
}
voidloop()
{
delay(500);
float rpm = myELM327.rpm();
float maf = myELM327.mafRate();
float kph = myELM327.kph();
float coolanttemp = myELM327.engineCoolantTemp();
float engineload = myELM327.engineLoad();
if (myELM327.status == ELM_SUCCESS)
  {
if (WiFi.status() == WL_CONNECTED)
    {
      HTTPClient http;
      http.begin(serverName);
      http.addHeader("Content-Type", "application/json");
      StaticJsonDocument<200> doc;
      doc["rpm"] = rpm;
      doc["maf"] = maf;
      doc["speed"] = kph;
      doc["coolant"] = coolanttemp;
      doc["load"] = engineload;
      String requestBody;
serializeJson(doc, requestBody);
int httpResponseCode = http.POST(requestBody);
      http.end();
    }
  }
else
    myELM327.printError();
}

view raw Fuelmanager_OBD.ino hosted with ❤ by GitHub

Step 5: User Interface

This is the User Interface,

Here you can see the information that the Fuelmanager device collects and calculates

In the settings Page you can set the specifications of your vehicle.

Change the Fuel Price everytime you refuel to the actual price, the system remembers the history of the fuelprice

Step 6: Database Design

Measurement

Every second while you drive your vehicle with Fuelmanager installed, the ESP32 reads the OBD2 Data and parses it to readable data. That data is sent to the Flask API with a POST request.

When it arrives, the API stores it in the database together with the timestamp of the measurement and the data from the GPS module connected to the Raspberri Pi.

Tour

When you start to drive and the system reads that there is data in the Measurement table, it starts to process all the data in to relevant information and even creates a GPX file from the GPS data. Everything is then stored in the table Tour. If we want to display every tour we have driven we can just take the data out of the table Tour. When everything is calculated and stored, the Measurement table is cleared (truncated) so that we can start a new tour.

Vehicle

Here the parameters of the vehicle are stored, the most important variable is: Current_FuelPrice. Every time we want to see the costs, the current fuelprice of that day is used. That means that we need to set the Fuel Price every time we refuel and the price changes.

User

This is the data of your personal login, it stores your user information and your password hash.

Step 7: Automating Startup

Let the backend start whenever the Raspberry Pi powers up, thats whenever your vehicle starts the engine.

sudo nano /etc/systemd/fuelmanager.service
Paste the content below
CTRX + X Y to save
sudo systemctl enable fuelmanager.service
sudo systemctl start fuelmanager.service

fuelmanager service

[Unit]
Description=Fuelmanager
After=network.target
[Service]
ExecStart=/usr/bin/python3 -u /backend/app.py
WorkingDirectory=/backend/
StandardOutput=inherit
StandardError=inherit
Restart=always
User=
[Install]
WantedBy=multi-user.target