I was finally motivated to get my hands on some Bluetooth hardware so I could figure out why my latest ASCOM driver wouldn’t work with Bluetooth. I found mine at U. S. Converters. I needed two–one that would plug into a USB port on my notebook (I bought model BLDONG for $9.99), and one that would plug into the serial connector of my digital setting circles interface (BT232B for $45.00). The BT232B serial Bluetooth adapter also requires a gender changer because it has a female DB9 connector just like my DSC interface, so I bought 10GC-D1 for $7.99, too. I know that AirCable sells this kind of stuff, too, but U. S. Converters seemed a little more economical.
Now it was time to get it all hooked up and functioning.
The BT232B adapter needs to be powered. There are three options:
- a USB cable (only for power, not data)
- an external 3V – 5V battery (not included, but a small cable and connector are included)
- 5V at pin 9 of its DB9 connector
I chose option 3. Since my DSC interface board already has a 5V supply available, it’s a simple matter to feed it to pin 9 of the DB9 connector (note, however, that this combination will consume more than double the current of the DSC interface by itself, so you’ll want to use something bigger than a 9V battery to provide power). Here’s a photo of how I installed a small jumper wire on the underside of the board to provide the 5V at pin 9 (click to enlarge):
Be careful that the jumper wire doesn’t short with any other circuit board traces.
Once the board is providing 5V to pin 9 of the DB9, you’ll need to set a switch on the BT232B. There’s a switch that determines whether it’s expecting power on pin 9 or from the USB or external battery. Set the switch so that it expects power from pin 9. As a test, you can plug the BT232B into the DSC board (using the gender changer) and then power up the board. The BT232B Power LED should glow red, and the Status LED should flash blue.
The next thing you’ll need to do is configure the BT232B for 9600 baud, 8 data bits, 1 stop bit, no parity, and no flow control. The included instructions tell you how to do this, but the basic procedure is to set it for DCE (there’s a switch on the side to change it between DCE and DTE, depending on whether your plugging it into a computer or another device like the DSC board), plug it into a serial port on your computer (or through a USB-serial converter), give it power (the USB cable is convenient for that, but change the power selector switch), and then connect to it using Hyperterminal at 19200 baud, 8 bits, 1 stop bit, no parity, no flow control. you can then type commands in Hyperterminal that will change the configuration of the BT232B.
First, type “AT” (without the quotes) and hit the Enter key. The BT232B should respond with “OK” (again, without the quotes). If not, double check your settings and switches and try again.
Then type the following commands:
After each command the BT232B should respond with some sort of confirmation of the command. However, after you set the new baud rate, Hyperterminal will no longer be able to communicate with the BT232B because the baud rate was changed. Don’t sweat it–you’ve done everything you needed to do.
Now you should be able to disconnect the BT232B from the computer. Set it for DTE and for getting power from pin 9 of the DB9, and plug it back into the DSC board, and power it up. If your PC doesn’t have built-in Bluetooth, you’ll need to insert your USB-Bluetooth adapter into a USB port (don’t forget to install any drivers if needed–check the documentation).
Now turn on Bluetooth on your PC and connect to the BT232B. Usually this is done by right-clicking on a Bluetooth icon in the system tray and selecting Connect from the menu. Windows will search for nearby Bluetooth devices and give you a list from which you can choose the serial Bluetooth adapter. Once it’s connected, it will hopefully report which COM port it’s configured as. If not, go into the Device Manager (right-click on My Computer in the start menu and select Properties from the context menu) and look at the list of ports to determine which port number is assigned to the serial Bluetooth adapter.
If you want, you can use Hyperterminal to connect to that port (9600 baud, 8 bits, 1 stop bit, no parity, no flow control) and test the connection. Once Hyperterminal connects to the port successfully, the flashing blue LED on the BT232B will stop flashing and glow steady blue. Try typing “H” and “Q” (without the quotes) and see if you get a response from the interface. If not, go back and double-check your steps and try it again.
Now you’re ready to use your favorite astro software with the DSC interface via Bluetooth. Just make sure that you set the COM port in the Settings to be the one for Bluetooth.
Let me know how it goes.