Bluetooth communication


This assignment made me step way out of my comfort zone. Even though wireless communication between devices is something incomprehensible to me, and establishing it myself seemed like a daunting task, I still wanted to learn more about it. So I decided to challenge myself and give bluetooth, the seemingly the most favourite technology for wireless communication between boards, a try.

For those reading this that share my feelings, these websites helped me understand the principles and processes behind it:
Arduino with Bluetooth module
Connecting a Mac to Bluetooth
work from a previous How to make student
the RN487x manual

I decided to make a board with an Attiny, LED, and a Bluetooth module and try to send a wireless message from my computer to the board telling it how frequently to flash the LED. I used the RN4871 module.

Before testing the bluetooth connection, I programmed the board to continuously blink the led. As soon as that proved to work, I proceeded to adding the bluetooth functionality. Conveniently, much of the logic behind it was similar to the code used for the camera interface I worked on in week 10, so code related issues were already sorted out.

Unfortunately, I was not able to connect to the Bluetooth module to test the code. From the user manual I understood the device should show up with the name BLE-xxxx. The module did not appear on any of my devices, including the app BLE scanner that I downloaded. I checked my board with a voltmeter and the module is receiving 3.3V of power and is connected to ground. I asked Brian for help, but we were not able to determine what could be the issue. We discussed that perhaps the Attiny has to initialize the module, but could not find any evidence of that online.

In the following class I learned that both the Attiny and Bluetooth module have to be powered at 3.3V. So upon return to the lab I removed the 5V regulator, and added a jumper wire to connect the Attiny with the 3.3V output from the regulator. I had issues getting enough power out of the regulator (upon measuring with the voltmeter it showed it was outputting only around 1 V instead of 3.3V). Exchanging the regulator for a new one did not solve the problem, in fact, it did not output any power after that.

When I accidently fried the Bluetooth component when checking traces with a voltmeter, I decided it was time to let this project be and start with next week's assignment.