MKII : Some re-engineering MKIII ?

Posted: 2010/12/28 in Hardware

Always learning… that’s a good thing… my plans to use the RS-232 serial interface from the BeagleBoard to the BS2/motor/servo controller got derailed when I realized that the port is already used to “communicate” to the console during the boot of the BB.   Yes, I could disable this and change the boot system, but I really don’t want to mess around with the boot loader and want to keep my console access as a safety measure… and it turns out that the BS2SX also uses some “interesting” f/w on its RS-232 port to communicate with the programming PC… it echoes every character received.

So, that means I had to come up with a different scheme for the communication between the master BB and the slave BS2 controller.  I opted to connect the BS2 via USB to the BB.  I’m using a nice prototype board from SparkFun as the USB i/f and carrier for the various BS2, motor & servo controller boards.  It has plenty of room for all the boards and provides a very nice/clean USB controller and interface.

This is what the modified rover now looks like… I had to move the carrier board closer to the BB and also move the USB hub to ensure everything would connect properly.

You can see from left to right, the servo controller, the motor controller (with heat sink), the BS2SX stamp and USB hub mounted on top of the BeagleBoard.  It makes a nice compact controller complex.

The RS-232 cable that you see in the picture is connected to the programming PC running the Parallax Basic Stamp editor/programming under Wine on my Ubuntu Linux desktop, more on this later.   This cable is removed in normal operation.

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