The source code for EkBoxTester can be downloaded from here. It was written using Microsoft Visual C# 2010 Express Edition–a free but reasonably complete development environment for writing .Net applications in C#. You can use the source code as an example of how to communicate with an EkBox via the serial port.

When you launch EkBoxTester, the following window appears:

EkBoxTester Initial View

It’s pretty simple to use. Select the COM port to which your interface is connected, specify the encoder resolutions, and then click the “Start Test” button. When you click the “Start Test” button, EkBoxTester will attempt to open the COM port and send the command to the interface to set the encoder resolutions. If this doesn’t succeed, you’ll see an error message that will describe the specific problem encountered. Otherwise, if everything succeeds, the EkBoxTester window should now look like this:

EkBoxTester after "Start Test" is clicked

At this point, the numbers in red should change as you turn the encoders. If you don’t have any encoders connected, you’ll still see the red numbers but they will not change (obviously), but this is an indicator that things on the board appear to be working correctly. You can click the “Get Errors” button to see how many encoder errors have occurred (generally, none) and the “Get Resolutions” button to query the interface for the current encoder resolutions (which should be the same as what you specified in the inputs toward the top of the window).

Once you’re finished, click the “Stop Test” button, or just exit the program by clicking the red X in the top right corner.

USB Digital Setting Circles Schematic

The kit is much simpler than the serial version–the pull-up resistors were eliminated, the oscillator replaced by a crystal, and a MAX232 chip is no longer needed. The board and encoders are powered by the USB port, too, so no external power supply is needed. The kit includes all the components, including the programmed PIC chip, but does not include the TTL-232-5V cable. The cable must be purchased separately and is readily available from Mouser and Digikey, for about $20 plus shipping.

This kit should work great if you want to run your digital setting circles straight through the USB port of your laptop. However, if your goal is to use a bluetooth connection between your computer/PDA/smartphone and the board, then the serial version of the kit is the one you want to use. Furthermore, this USB version really isn’t adaptable for use with a smartphone or PDA–the TTL-232 USB cable needs to plug in to a PC in order to work.

Now it was time to get it all hooked up and functioning.

The BT232B adapter needs to be powered. There are three options:

1. a USB cable (only for power, not data)
2. an external 3V – 5V battery (not included, but a small cable and connector are included)
3. 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):

DSC board with jumper to provide 5V to pin 9 of the DB9

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:

• PARITY=N
• FLOW=N
• BAUD=9600

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.

Hi Guys,
I came up with a newer board that fits nicely in a roughly 3 3/4″ x 2 3/8″ x 1″ enclosure that has a space for a 9v battery. So I have some complete systems that I’m selling for $100, and that includes some encoder connectors. I’ve uploaded a photo here: http://groups.yahoo.com/group/Palmastro/photos/album/710692234/pic/list

Craig Combes

Earlier this year Craig sent me a description of his bluetooth DSC system which I added to my Digital Setting Circles pages. Go there for a full description. Contact Craig directly if you have questions or want one of his systems.

Thanks, Craig!

Here’s one for starters:

If you know of any other good soldering tutorials and resources, leave a comment below.

Netbooks first popped up on my radar screen when I stumbled upon an article describing how somebody was successfully running Mac OS X on theirs. That was (and still is) intriguing to me–OS X is supposed to be pretty slick, but I’ve always been put off by the Mac price tag. But I digress.

One of the attractive things about netbooks is they’re cheap. My MSI Wind U100-843 with 2GB of memory and a 160-GB hard drive ran me about $300. After having it for a few weeks now, I’m impressed with it. It runs Windows XP Home SP3 like a champ. The netbook itself is built well, and the battery supposedly will give me six hours of operation (I haven’t really tested this yet, though). It’s quick to boot, has a great display and a decent touchpad, and wireless connectivity has been solid. In short, everything works. That’s not a given with PC hardware these days, so it’s nice to experience it.

One of the things I didn’t really consider before I bought my netbook was whether it would be handy for use with my Digital Setting Circles project and a telescope. The netbook has no serial port, of course, so I’d have to use a USB-serial converter to plug the digital setting circles into my computer. A while back I picked up a really cheap converter on Ebay, and I figured this would be a good test. So, I loaded up TheSky 5, the ASCOM platform, and my own ASCOM driver and put the system through its paces.

There was no reason to think that the system wouldn’t work, and I was right–everything worked flawlessly. Even the el-cheapo USB-serial converter did its job magnificently. (For the life of me, I don’t understand why these converters have gotten such a bad name. I’ve never had difficulty with one. And a lot of USB devices make use of them internally so that separate USB drivers don’t have to be written for those devices.)

I originally designed my digital setting circles project to be used with a notebook computer, but many folks these days are using it with a PDA or smartphone because of the portability of such devices, the availability of software for them, and the fact that they often support bluetooth for wireless connections between telescope and computer. Still, handheld devices are definitely a compromise of power and versatility for convenience. Netbooks are now in a price range comparable to these handheld devices and provide nearly the same convenience of portability while being vastly superior in capability. I could easily envision using the netbook with my digital setting circles while simultaneously using it to control a digital imaging system and log my observing session–a tall order for a handheld device.

The handheld device landscape has shifted dramatically over the past few years. While PDAs running Palm OS and Windows Mobile once ruled the land, they’ve been largely obsoleted by smartphones like the iPhone and the Palm Pre. While software developers are catching up to the new platforms, one needs to actually own a smartphone (with its higher costs for broadband service) in order to use the software. Handheld alternatives to smartphones are disappearing fast. Netbooks don’t carry the extra baggage of requiring a monthly payment for cellular network access (unless, of course, you purchase one from a cellular carrier for precisely that purpose).

I know many people who love their iPhones, but right now I’m too cheap to pay for being connected to that degree. Maybe I’m just an old curmudgeon. In a couple years I’ll probably be an iPhone-wielding drone just like everyone else. In the mean time, I gotta go see if I can find that article on how to turn my netbook into a Mac…

Eddie wrote:

Dave,

I have finally managed to get the Bluetooth connection working with your interface and Cartes du Ciel. I will let you know what I had to do and the setup I’m running so that you can let other people know if you get asked the question.

Program: Cartes du Ciel
Serial Bluetooth adaptor: Sena Parani SD200
USB Bluethooth adaptor: Sena UD100

Information for the Bluetooth adaptors can be found on www.sena.com

You have to plug the SD200 into a computer with a serial port in order to set up the adaptor. The adaptor gets set to mode 3 with command response set to on. Using the Dip switches on the SD200 the Baud rate and flow control can be set to 9600 and off respectively, the other parameters are set at the factory and cannot be changed. When connecting the Bluetooth adaptors the UD100 will need to be forced to operate on one of the local com ports i.e. 1,2,3…. etc so that it can work with your interface.

Then I had to make up a null modem serial adaptor between your interface and the SD200 adaptor. Pins 2 and 3 have to be crossed over in the connector and 5 is straight through. Cartes du Ciel doesn’t like handshaking and therefore the remaining pins must be left off or the tracks on your PCB have to be cut.

Once all of this is done your interface works very well and the laptop can be setup remotely from the scope so that wires aren’t being tripped over or having to attach your computer to the scope itself.

I hope that this information will help you and any other Astro nuts out there setting up their interface with a Bluetooth connection.

Thanks, Eddie, for passing on that information.

I’ve heard of other users who’ve successfully used similar devices, especially those from AirCable. I don’t have any personal experience with any of these devices, but they’re an occasional topic of conversation in the Yahoo Groups’ PalmAstro group. I’d welcome any and all reports of other bluetooth adapters being used with my DSC system–just leave a comment below.

If you’ve used another enclosure and liked the results, leave a comment below and tell me about it.