Arduino Bluetooth car with Lego

This repository contains the source code of my Arduino Bluetooth car built years ago with Lego.
The code was written between 2015 and 2016, when I was younger, be patient if it's difficult to read ;)
This car has Autonomous Emergency Brake and autonomous lights as standard.

This car has a 90 degree steering wheel. This movement is carried out using a servo motor embedded inside the car.
This Lego car is completely self-made: I removed the gearmotor from my grandfather's old printer, I cut the battery container from an old RC controller and I took all the Legos from my old toy (Lego technic 8041).
I also learned to use the soldering iron and I never got burned using it!

How it works:

The last version of my Arduino car works with Bluetooth, using HC-06 module: this means that I had to create an Android application that could send commands to my car.

At that time I was certainly not able to write apps for Android in Java, so I had to arrange with App Inventor.
If you want to edit the application you can import Mark_8_controller.aia in your App Inventor account.

The application is able to detect all Bluetooth devices and establish a connection. After connecting you can control the car in 2 ways: with the buttons or using the accelerometer of your smartphone.

The app send this types of command to the Bluetooth module:

• SINISTRA: Steer left
• DESTRA: Steer right
• DRITTO: Steer forward
• AVANTI: Motor forward
• INDIETRO: Motor back
• CLACSON: Use clacson
• LUCION: Turn on lights
• LUCIOFF: Turn off lights
• LUCIAUTO: Auto lights (with brightness sensor)
• AIRBAGON: Turn on Autonomus Emergency Brake
• AIRBAGOFF: Turn off Autonomus Emergency Brake
• AUTOON: Autopilot beta on
• AUTOOFF: Autopilot beta off
• DISCONNESSIONE: Disconnection

The HC-06 bluetooth module must be connected to Arduino serial TX and RX. When new data is available it will be parsed. The code below shows an example of receiving the command.
NOTE: When you upload new code to Arduino remember to disconnect the HC-06 module from TX and RX.

void loop() {
	...
	while (Serial.available()) {
		delay(8);
		char c = Serial.read();
		readString += c;
	}

	if (readString.length() > 0) {
		Serial.println(readString);

		if (readString == "SINISTRA") {
		  Sterzo.write(sinistra);
		}
		
		...
	}
}

Components:

These are all the components used in the last version of the car:

• Arduino Uno rev3
• 9V DC motor
• L293D: dual H-bridge motor driver for DC
• SG90: servo motor
• HC-06: bluetooth module
• HC-SR04: ultrasonic distance sensor
• 5 x leds (2 x red and 3 x white)
• Photosensitive resistor (light sensor)
• 6 x 220 Ohm resistors
• Buzzer
• 6 x 1.2V batteries with container
• Switch: to turn on/off the car
• Breadboard
• Lots of wires
• Lots of Lego technic

This is the steering system, seen from below. It's composed of a servo motor and various Lego gears.

Previous versions:

Mark 4:

One of the first version.

Mark 7:

This seventh version was controlled by an infrared remote control.
In the photo on the right the Arduino has been replaced by an ATmega328P.

Mark 8:

The last version.