THE C328 LIVES

After 3 weeks of hacking, the C328 started producing decent results. Your main problem if you intend to control it from a computer on the ground, using Xbees, is getting the UART to work reliably. It needs a real clean signal & short cables to work at 115200. Initializing it still takes several power cycles & 20 second delays. Decided 320x240 is the best compromise between resolution & frame rate.

We use a microcontroller to generate ACKs locally but generate every other control code from the ground.


Fuggetabout dual 2.4Ghz Xbees for telemetry & video. They interfere even when on different frequencies, spaced 2 ft apart, using wire antennas. You're still stuck with 900Mhz for video. While no radio combination is completely interference free, got good results with 2.4Ghz for autopilot & 900Mhz for C328, even when they're right next to each other.

Set the 2.4Ghz for broadcast mode, 0 retries. Set the 900Mhz for addressed mode, 3 retries. We use 2.4Ghz for flight control & 900Mhz for video.

Even though the C328 allows video capture, we have never used the captured footage. It just sucks too much. The C328 has a rolling shutter. We use a main camera recording to flash & the C328 as a preview camera.

The perpetually out of stock rangevideo.com has drastically reduced the prices of 900Mhz video. If you have the licenses, he ever stocks anything, & you don't mind buying analog video capture hardware, it's now a better deal than a C328 + 900Mhz XBees.

Have a tail rotor rebuild.



1st crash damage since becoming Major Marcy enabled was this tail rotor during the roof crash.

Took a 400ft timelapse on Halloween while the rest of you were partying.


This video shows the key steps in stabilizing.


For the timelapses, we use 1 battery to aim with the C328 at 33m. Last month it was 32m. Now it's 33m. Then program the heading into the flight computer & burn another battery to shoot the footage fully autonomous at 120m. Until better radios come along, those 120m flights need to be as autonomous as possible.



In flight preview on the C328.

FLIGHT COMPUTER RESETS

Next, rediscovered if the servos are not powered & the flight computer generates PWM, the servos may act like short circuits & cause the flight computer to reset. Not an issue on standard autopilots, but VicaCopter has 2 power circuits. 1 circuit powers only the flight computer so U can get GPS locks. Her flight computer doesn't generate servo PWM unless the transmitter is on.

PROPELLER CRACKS

Finally, discovered cracks in our GWS 12x6's. They were drilled 1 size too small, threaded on the shafts & probably had too much stress. Important safety tip. Drill big enough so they glide on the shafts.







Normal propeller

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100KM
Comment by crystal garris on November 8, 2009 at 2:16pm
cool camera i am guessing it works on the same line as this 4d's ttl camera ?
Comment by isobot on November 8, 2009 at 4:47pm
Col. Crossfire,
My guess is the serrated edges of the star lock washer might be contributing to the cracks in the props.
Comment by Jack Crossfire on November 8, 2009 at 11:10pm
The camera is described on http://diydrones.com/profiles/blogs/secrets-of-the-c328. The protocol is identical but the Australians sell a better lens than the Chinese.
Comment by eclipse on January 10, 2010 at 3:44pm
Hey,

How did you manage to wire the c328 camera and Xbee at the same time since they both use Rx & Tx ?
Comment by Jack Crossfire on January 11, 2010 at 6:06pm
The magic schematic.

Comment by eclipse on January 12, 2010 at 9:49am
Hey thanks Jack,

now i looked back at the http://diydrones.com/profiles/blogs/secrets-of-the-c328 i saw a similar schematic already so sorry for that.
As i can see in this schematic you are not sending any data from the ground to the plane via Xbee.
But in the other one the From xBee and Tx were connected. Didn't it work ?

Do you think it would still be possible to send and receive data other than the pictures from the c328?
Comment by Jack Crossfire on January 12, 2010 at 11:07am
The other schematic worked. To send data other than the C328, you should use a proper multiplexing chip.
Comment by eclipse on January 12, 2010 at 12:52pm
ok, so the multiplexer is connected to Rx & Tx (i'm using an Arduino Duemilanove) and then you can either send a command to the c328 or send/receive data via Xbee am i right?

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