Mobot BTCar: Controlliamo una RCar dal nostro Android con Arduino!

Buon lunedì a tutti! Finalmente è arrivata l’ estate e quindi (almeno per me) le ferie e senza l’ assillo del lavoro potrò dedicarmi di più al sito! Ultimamente mi sono avvicinato molto al mondo della domotica e di Arduino e devo dire che è davvero pazzesco cosa si possa fare con quell’ aggeggio!

Ho trovato un progetto molto carino di uno Spagnolo (il link del sito è a fine articolo). Consiste nel montare su una RCar molto economica un arduino “UNO”  compreso di modulo bluetooth con dentro un programma appositamente scritto al posto della “centralina” dell’ auto e poi controllare quest’ ultima tramite un device android attraverso l’ apposita app (1.5+). Arduino in questo progetto riesce a controllare ben 8 led, una funzione denominata “Turbo” anche se non so se funzioni in tutte le rc-car,e quelle normali (Avanti, indietro, destra, sinistra). Io purtroppo per mancanza di tempo non ho ancora provato ma intendo farlo durante questo periodo di riposo in quanto  davvero un bel progetto (forse non molto utile XD ). Vi trascrivo le istruzioni dal sito ufficiale di cui trovate il link a fine pagina.

MOBOT BT Car is a simple project that has helped me to get familiar with the Arduino platform. The project involves the modification of a small low cost car radio, to which he has attached an Arduino ONE and a Bluetooth module to communicate with the board and deliver the orders. Furthermore, it has added a complete lighting system that includes short lights, long lights and reverse lights.

Components

• 1/16 RC Car
• Arduino UNO board
• Bluetooth Module (model: BT0417C)
• 6 white LEDs
• 2 red LEDs
• 4 AA batteries
• Ni-Mh 650mAh battery
• Wiring

 

Construction

The first thing to do is remove the shell of the car to unscrew the board that controls the engines. If you look, the board has a microcontroller with 16 pins (8 on each side). Most cheap models have a RX2/TX2 Realtek chip or compatible with the design of entries shown in the picture. What we have to do is solder a wire to the outputs of the chip that control signals Forward, Backward, Turbo, Right and Left, in addition to the GND output that must be grounded. You can keep the chip, but as we wont use it, is best to remove from the board and dispose. All control signals will be done from the Arduino board.

Once we clear the pins on the chip to be bridged, it must be soldered to each of them. To facilitate this, do not recommend soldering directly onto the chip, but at some point in the board connected to each pin where already have a a spot weld. It is also advisable to put a label on each cable with the pin function that is welded to later find out which is which.

Welded pins:

• Pin 2 – GND
• Pin 6 – Right
• Pin 7 – Left
• Pin 10 – Backward
• Pin 11 – Fordward
• Pin 12 – Turbo

 

Now let’s look at the issue of lights. The model I used was 2 white LED headlights that lit when the car was to the front and 2 red LED tail lights that lit when the car was to the rear. Also, I joined a second set of 2 white LEDs more powerful illumination for use as long lights and other 2 for the reverse function. To install it, I had to pierce the fog with a screwdriver to get the just gap to the new lighting.

We need to cut the wires of the LEDs to the original board. To control the LEDs (both new and originals) we need new wiring. The short pins of the 8 LEDs(anodes) are wired together and all go to a GND input of the Arduino board. The long pins will be wired in pairs (the two LEDs for short lights, the two LEDs for long lights, the two LEDs for taillights and the two LEDs for reverse). Each of these pairs will be coupled with a 1K resistor to prevent the LEDs from burning. Each resistor will be connected to the corresponding pin.

In this moment we have all assembled. Now we have to punch each wire of which we have prepared in the corresponding pin of the Arduino board. The following explains the corresponding pins for each item:

• Pin 12 – Fordward
• Pin 11 – Backward
• Pin 10 – Left
• Pin 9 – Right
• Pin 8 – Turbo
• Pin 7 – Short Lights
• Pin 6 – Long Lights
• Pin 5 – Tail Lights
• Pin 4 – Reversing Lights
• TX – RXD of the BT Module
• RX – TXD of the BT Module
• 5V – 5V of the BT Module
• GND – GND of the BT Module / GND of LEDs / GND of Car Chip (Since the Arduino has 3 GND entries, you can use one for each of the specified wires)

In the next picture you can see the complete assembly of the circuit:

 

It only remains to solve the issue of power, both car engines and the Arduino. As we are using the own circuitry of the car, to power the engines we can use the standard battery system. In a first attempt, I tried to power the Arduino board with the same car battery, but then the batteries were not enough strong to power the entire circuit. For this reason, I had to use a second battery to power the Arduino. This battery has been taken from a model airplane and it is outside the car because of a space problem.

Arduino Board Programming

The following link provides access to the complete code for the Arduino board, which must be loaded into the board for proper communication with the Android client.

(Trovate il “firmware” nell link del sito ufficiale a fine articolo)

Android App

 

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