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.

LED Display

A while back one of my roommates bought 2 LED displays as part of a project idea. The signs kind of fell on the backburner as other things came up, but I thought that I could start playing with one of them since it shouldn’t need much work to get it operational again. The display is an Alpha 210A, and is missing both its power supply and controller. Normally a missing power supply wouldn’t be a problem, however this sign uses 7.5VAC. Finding a transformer with a secondary rating of 7.5VAC proved to be rather difficult, but I finally managed to find a place that had something usable. Herbach & Rademan carry a transformer that provides 7.5VAC at 1.5 amps, so I need 2 of them, as the sign is rated at 2 amps, but for $3.95 a piece I can’t complain. They do have a $15 minimum order but they had other items that I needed anyway. Their site does not have a secure checkout, so you might want to consider calling or faxing your order.

The next issue, of course, is the programming controller. According to the Alpha website, the displays use either RS-232 or RS-485 to communicate with the controller. I’m not sure which standard my sign uses, but if its RS-232 conectivity will be easy. RS-485 shouldn’t be a problem but will require an adapter. I’ll look for the specifics of the communications once the transformers come in and I can verify that the sign actually works.