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Edward McCreary
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I bought a RC transmitter for use with my R2 for $40, a nice kit that includes a receiver. Thanks Scott. It also has a 4-pin mini din connector on the back for firmware updates and to allows you to connect it to a PC for use with a training simulator. Hey, I thought, that means there must be a signal coming out the back with the control signals. After a bit of reading it turns out most transmitters send a PPM signal over the training line.

I took a MicroView arduino with an embedded OLED display and wrote a basic oscillosocpe program. I first tested it against another's scope test signal. Then I tried it against the various rear pins and sure enough there was a square wave on one pin. The next step was to decode it.

A bit of an aside, I grabbed an old S-Video cable since it is also a 4 pin mini din and chopped it up. One issue, turns out for S-Video the outer ring is not connected, one of the four pins is ground. But for these RC transmitters, they use a custom cable with a fifth line connecting the outer shell for ground. I was able to cut back the plastic around the connect and wrap a wire around it, solder it in place, and use that for ground. It looks hideous but it worked.

It turned out to be trivial to decode the ppm signals. I setup a 0.5us timer and added a irq handler to one pin. I was able to see an obvious grouping of 8 short pulses and one long on to indicate start for 8 data channels. The transmitter supports 10, but only under their proprietary serial protocol.

The video is the data plotted for the various controls as I moved them.

Now, the idea is to connect this to a NRF24L01 transceiver and see if I can control the micro quadcopter I have. And this means by software I can controls many types of devices. Many more expensive transmitters have radio modules you can swap out, but I’ll be able effectively to do the same thing with a $5 mini pro Arduino and a $2 transceiver.

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I wonder how many of these ideas actually were turned into stories? #writing  

I challenge my fiction-writer friends to take a stab at any of them.
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Added some wash to bring out the panel lines. I think I need to attach the legs to the bottom of the stand, either blue stick take or rods. And I think there is room for the BB-8 model.
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