Building the Electronics


#1

I found the OpenROV project when I was researching embedded linux & micro controllers. I wanted work with these embedded types of devices and while looking for something to accomplish that would help give me a reason to continue making progress I stumbled onto the OpenROV and decided this was as good a place as any to "learn by doing" so here I am. Over the last few days I have been working on building the electronics and made decent progress.


Attached to the breadboard is my attempt at reproducing the schematics and putting a 5v power supply and Arduino onto a breadboard and connect it to the beagle bone via the tx/rx pins. I used a reset button instead of wiring the reset of the Arduino into the BeagleBone like the schematics. I plan to do this eventually but I need to pick up a transistor. Somehow I lost the only one I had. At this point I have the power supply done (including the 9v backup) and am powering both the breadboard rails and the BeagleBone via the 5v supply.

I haven't completed testing since I haven't fully been able to connect the BeagleBone to the Arduino. When I enable the tx/rx ports on the beagle bone the LED in the link to the Arduino illuminates on the BeagleBone TX. It stays illuminated and I would expect it to pulse when data is sent from the BeagleBone. In my mind a constant illumination tells me a constant data stream is being sent and I don't believe that is correct? I am at a loss to why I cant connect to the Arduino but when I fire up the Arduino Development Environment on the BeagleBone it does not find see an active Serial port. I believe somehow I am not activating it correctly.

I am attempting to activate the ports via this info here.

  1. echo 0 > /sys/kernel/debug/omap_mux/uart1_txd #setting mode of UART1 TX to in
  2. echo 20 > /sys/kernel/debug/omap_mux/uart1_rxd #setting mode of UART1 TX to out

On another note, I believe the configuration commands are correct, I think the comments are wrong. Shouldn't it be:

  1. echo 0 > /sys/kernel/debug/omap_mux/uart1_txd #setting mode of UART1 TX to out
  2. echo 20 > /sys/kernel/debug/omap_mux/uart1_rxd #setting mode of UART1 RX to in

Thoughts?


#2

Hey Dan,

Awesome build! This issue is a bit complex so it's hard to give specific advise. Bran and I found it really helpful to use an logic analyzer (http://www.saleae.com/logic16?gclid=CLSE5MCKmLMCFQQcpQodjDwAHw) to see if the UART was working properly. You could also use an o-scope to at least see if there are bits coming out of the GPIO pins. This could an issue with the GPIO settings in software, but also the schematic hasn't been fully vetted.

Anyway, I hope you get to the bottom of it, and sorry I can't offer more help!

Good luck!

Eric