Discussions

I have an interesting problem that I can't seem to figure out.  I have a APM1 on a hexa with a Win7 FitPC2i computer mounted on the hexa as well.  The PC is connected to Serial 1 and 3 on the APM1 via FTDI 3.3V USB to TTL converter cables.  I am using custom code on the APM1, but the majority is Arducopter 2.5.3.  The serial lines are sending/receiving data to/from the arduino and PC.

Here is the basic problem...

If the 5V power pins on the TTL converter cables are connected to the APM1, then the hexa flies fine, but the barometer and sonar and some other sensors are messed up theoretically due to reference voltages and the converters not being able to supply enough amps.  I understand that problem (I think).

If I remove the 5V power pins on the TTL lines, the sensors read fine, but the hexa is completely unstable!  It is almost like the gyros are turned off or inverted.  It won't even get off the ground because it will either flip or roll on takeoff.  When it is in this mode, if I remove the TTL lines and power cycle the APM1, then it flies just fine.

I've tried all sorts of different power on sequences, software startup, re leveling and other things.  I'm at a loss as to what could be causing this.  The TTL lines should not need the 5V power to operate properly.  That is just there for convenience to power the device you are connecting to.  All grounds are connected together.

Any guesses would be greatly appreciated!  I have no clue any more.

Mike