IR protocols & U

3689395970?profile=originalMarcy 1 actuator notes

So we tried making the actuator pull the flap instead of push it.  This made gravity the restoring force instead of air.  Maybe it wouldn't need as much power & could stay on full time.  FUGGEDABOUTIT.  It needed just as much power & quickly overheated.  Your best option is a pushing actuator.

Things went better with Marcy 2.  Payload test showed she probably could lift the Marcy 2 electronics package.  Now the IR protocol.


Inactive high.
960 bits/sec
start bit is 1/270 seconds low, followed by 1/1000 high
each bit is 1/960 seconds, beginning with a fall
1 bit is low for 1/2400 seconds
0 bit is low for 1/1200 seconds
1/40 seconds high between packets

From Darkstar2000's work on the obsolete 6020, we have the protocol:

8 bits: throttle 0 - 127
4 bits: yaw 0 - 15
4 bits: pitch 0 - 15
1 bit: left yaw if 1
1 bit: nose up if 1
1 bit: yaw trim left if 1
5 bits: yaw trim
2 bits: 11 for channel A
6 bits: chksum (sum of 1st 3 bytes + 0xf) & 0x3f
1 bit: 1

It transmits packets more frequently during a change.  Fortunately, Darkstar2000 also reverse engineered the S107, so changing protocols won't be a complete disaster.  Exactly why he did all this work is a mystery.



Next comes a new Marcy 2 board for azimuth sensing & sonar on only 3.7V.  It's pretty aggressively weight minimized.



Converting it to 900mhz was a no brainer.  Mounting the board for flight was a nightmare.  Servo connector or soldering?  Enough power in the flight battery to test the board?  Can you justify the weight of a servo connector or an aux power source + diode?  2 pin + permanently soldered data connection or 3 pin connector?  Eventually, it came to a 3 pin servo connector.


Our 1st flight test of a photodiode as azimuth sensor, indeed the world's 1st flight, was disappointing.  The signal had so many peaks, it would take herculean processing to convert it to a period & phase.  It would have to be flown with a single light source, at night.







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  • An alternative is to use output from the headphone jack using the IR transmitter that the Syma 107 is compatible with and then use your laptop to send the commands to it (not using the Syma app)... that way your S107 is left unmodified and you can pre-script simple take offs and maneuvers.

  • Developer
    nice hacking.  There are an endless number of these coaxial helicopters in all different sizes.  I wonder if many of them use the same protocol.  If yes, this is all good info that could allow them to be used without having to purchase a ton of electronics.
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