Posted by Jack Crossfire on December 11, 2009 at 10:30am
There it is. The coveted $3.30 14.7456Mhz crystal. With that & a small bugfix installed, the C328 works perfectly at 115200, the pictures stream continuously from the microcontroller & we're up to XBee lockups.Even 1 way communication locks up in this high interference environment because the ACKs collide. Your only option is broadcast mode. With broadcast mode & 3 retries, you now have more errors but the Xbees don't lock up. The command to set the number of retries is ATRR & it's undocumented on the XBee 900.With the 900Mhz & 2.4Ghz running simultaneously we now see the huge difference in range. The 900Mhz dies at 300ft, much closer than the 2.4Ghz. This is with wire antennas. Since 900Mhz has always been more expensive than 2.4Ghz, don't expect to get 2.4Ghz range out of 900Mhz for $42. High gain antennas are required. Dual 2.4Ghz modules don't work well either.So that's $140 for 300ft .2fps 320x240 video. Ended up with this arrangement because 900Mhz was originally supposed to be for telemetry. The C328 was a cheap way to get preview video by recycling the 2.4Ghz radio. It's clearly a disaster compared to what people are doing with a $90 Ativa/Camileo & $80 Range Video radio.http://rcexplorer.se/page14/hdcv/hdcv.htmlvideo.tar.bz2This is the updated source code for the wireless camera system.This is our full motion aerial footage of the Rain Ramon XMas tree. The autopilot was programmed to always point towards the tree, but L1 GPS & GPS derived heading being what it is there was a lot of manual intervention. If the weather wasn't already closed in for the year, we would fly this at 1m/s with manual heading & time lapse it to get more accuracy.Heading from the magnetometers & accelerometers back in the day was never very accurate either. Dynamic acceleration & local induction always made it approximate.& this is a segment from a very old flight showing a fast autonomous descent into downwash using the Marcy Maneuver.MARCY 1 VIDEO NOTESMain ideas for getting video out of Marcy 1 revolve around using 1 raster line of a chip camera like the TCM8230MD, but no data radio has enough bandwidth to do the job. So the best idea is to scan 1 raster line every several revolutions, stick with a photodiode for heading & use the rotation period to figure out where the rasterline was scanned. Accumulate rasterlines from many revolutions to construct an image.The camera would be read on a 2nd CPU. Data would be sent to the main CPU's UART & multiplexed on the main radio.MARCY 1 MISERY
So gEDA had the wrong footprint for an SSOP20 & we had to make a new ground station board. Fortunately it only requires remaking 1 side when your double sided boards are stacks of 1/32" boards.The PIC18F14K50 has USB & programming on the same pins, so in circuit programming is extremely slow without a bootloader & USB probably doesn't work with the programming header attached. You're looking at pogo pins & a jig.Since USB hasn't worked between this week's commutes, probably going to make the ground station radio a breakout board & use a chip with dedicated USB pins as the ground station CPU.
Flight computer ready.
MEET MARCY 2
While waiting for Marcy 1 parts to arrive from Thailand, started the Marcy 2 vehicle. She's planned as a backup indoor sonar demonstrator in case Marcy 1 doesn't work. The parts are all in apartment. Probably going to use the programming pins for PWM.She uses a no brainer 3 gyro, 4 PWM, 1 sonar autopilot. Could have just recycled Vika 2's autopilot but all our indoor vehicles need 900Mhz radio & sonar on the main board. Though capable of flying a tri rotor, Marcy 2 is planned as a tail sitter.The main problem is fabricating a tail sitter small enough to fit in a $1 million apartment.
:-) , tail Sitter , I like it , I see lot of work going on Jack, Like the looks of Mercy 2. Would love to see some sonar ( low altititude estimation for landing flare)integration in DIYdrone projects Jack.:-), good work
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$1 million dollar apartment? Did you move to San Francisco???? : )