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Car B-Lock

ECD Projects: Car B-Lock


By Behlol Nawaz

Continuing in our series of Bluetooth enabled semester projects; we look at another interesting one in this post. Adhering to the requirements of using a development board with a Bluetooth 4.0 chip (a.k.a, Bluetooth Low Energy or BLE) and an Android phone application, the project featured in this post is related to cars.

Before this, we first saw the wireless Bluetooth speakers, “Audink” and then the notification watch, “Notify-U”. Now we will have a look at “Car B-Lock”, a device that allows the user to interact with the locking system of their car via their Android smartphones.

Project name: Car B-Lock

Students: Mohammad Shahzeb Faisal, Asad Ali Malik and Abdul Moiz.

(All students of BEE-4 at SEECS, NUST)


Drawing on inspiration from wearable gadgets, the team of students working on this project wanted to create something that allowed more convenient use of an everyday object. They focused their attention on cars.

Initially, the project team wanted to develop a system in which the doors would lock and unlock, based on whether the driver (with his smartphone) was in the car’s vicinity or not. Such a system would improve the security without the normal inconveniences.

In the end, they also added the feature of manually controlling car doors.

Design and Operation:


Like most other projects, this one also used the RFduino development board, which has a microcontroller with Bluetooth connectivity. The actuating motors of the car’s locking system were connected to an RFduino. The RFduino would communicate with its Android phone application via bluetooth. Only its own application on a specific phone could connect with the RFduino.

As soon as the associated phone was within range, the RFduino in the car would connect to it. By default, this connection would trigger the RFduino to unlock the car’s doors.

For the manual locking and unlocking from the phone, the phone would communicate with the RFduino over Bluetooth. Choosing a particular option in the phone’s application would send a specific signal to the RFduino. Each possible action had a different kind of signal. The RFduino would see what the specific signal was and turn one of its I/O pins high accordingly. Depending on which specific pin had a high voltage, an external circuit would be triggered that manipulated the required actuating motors via a motor driver IC. Thereby locking or unlocking the required doors. The version demoed could control the doors on either side or all four doors together.

The development and demonstration was carried out on actual car locks. So what was developed was not just a proof of concept. It could be integrated into a car with minimal effort.

Challenges faced:


After finalizing the prototype, the students found that the actuators’ motors were drawing a lot of current so the current had to be limited to keep the ICs and motors safe.

Another related issue was that with the reduced current, the actuator motors were not providing the expected force that could push a door lock. To overcome this problem they had to use polar capacitor of a very high value. As the actuating motors run only for short periods of time, extra charge would first be stored on capacitors in parallel with the motors and they would then provide a sudden influx of large current that would provide the necessary force.

The project’s team was enthusiastic about extending the project further to control (or interact with) other features of the car possible. They can range from ignition, to the cooling/heating systems, to the entertainment system or even the status/health of a car’s different indicators or parts.


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