Bluetooth Comes Alive!

Despite my lack of posting, I actually have been working on my bluetooth hardware, and am proud to report that I have had my first successful bluetooth wireless communication between my Windows machine and my CB280 microcontroller (its based on an Atmega128). Using Hyperterminal, I connected to the outgoing COM port created when the bluetooth dongle makes a connection. The program running on the microcontroller switched LED’s and relays on and off depending on the ASCII character that was sent. Currently, the program only recognizes single character commands, and the next step is to expand that to include entire character strings. On the hardware end, I want to eliminate the use of RS232 as the communication method between the microcontroller and the ACODE-300 bluetooth chip. By using RS232, I am required to use a RS232 converter board for the bluetooth chip. If I eliminate that, I can use direct TTL for the communication, which will give me reduction in power consumption and in the amount of hardware needed.

Getting this far was not without its problems, however. I did manage to fry 2 of my RS232 conversion boards ($20 each) as well as one of my bluetooth chips ($60). First mistake was using what turned out to be a 9V AC power supply on the chip. This proved disastrous for the bluetooth chip, but also means that I now have a power supply for my Alpha 210A LED sign. Programming that will come later, since increasing the functionality of my bluetooth setup is my current priority.


  1. What I was wondering is the way you are establishing a connection without authentication. I am trying to connect a normal USB Bluetooth dongle to a printer and then send commands to this BT dongle. What I am failing to achieve is to connect to this BT dongle because it can’t send response to calls for a new connection or authentication. How do I achieve a simple ASCII send to a BT dongle connected directly to a printer.

  2. I was configuring the bluetooth devices to only connect to each other, so the connection authentication was hard coded. The remote dongle would only connect to the device I was using to talk to it, and no others. I could leave it open, and allow all connections, but that would be a security issue.

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