BLE Proximity Sensor

By Keon Khodaei
Intermediate Category (Grades 9-10)
Experiment | Engineering and Computer Science

Everyone leaves something behind now and then, and this project was set to eliminate that problem. My project aimed to send a text message to a mobile phone to alert the user that they had left something behind immediately. For example, if you accidentally left a personal belonging behind at a restaurant, you would be alerted after you were at a pre-defined distance away from the item.

I coded a FireBeetle ESP32 Arduino board using the Arduino language to send the message via Bluetooth Low Energy (BLE). The initial goal was to send the text message directly to the smartphone after a certain distance was passed but this proved to be impossible as the board didn’t support a SIM card. Therefore I used a third party application to send the message.

During this project, an experiment was also conducted to find the “cut-off” value that was appropriate to know when to send the message. That experiment taught me that Bluetooth signals aren’t very reliable and fluctuate unexpectedly, which sometimes causes the Arduino board to send the message randomly. The code was optimized as best as possible and yielded the expected results.

The BLE Proximity Sensor is an all-round useful device that alerts the user of their missing items. With the use of BLE, the device is able to send a text message on to a downloaded app on the users’ smartphone, notifying them of their missing belongings. By simply modifying the code, the user can also shape the device to his/her own needs while still maintaining its original purpose.

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