Discussions

I am hopefully  finishing a build (y6 Trooper) today and my flight controller isn't coming in for a while so I've decided to use either my Pixhawk or SuperX that I have on 2 of my quads. 

I'm leaning towards the Pixhawk, but am hung up on the 6s power issue and after researching for what I can do today, I have a few questions.

A 2nd question is I  am wondering if I can use my old pixhawk controller (sitting in a drawer)  that the GPS compass connection got pulled off the board. 

Question 1. 

1.  I have successfully flown my Pixhawk with 5v power to the rails.  I did this on a 4s quad using a buck converter to supply 5v while I waited for a replacement power module that shorted out.  For the short term, if I am not going to monitor my battery usage and levels, I have come up with 3 potential ways to power it.

1A.  Use a 5 volt source from the Trooper y6 PCB board (there are 3-4 5v output connections) and run that into my rails on 7 or 8 output pins (as I'm just using 6 motors).    This is the simplest, but this statement worries me a bit  from this doc  http://drones.webstanz.be/blog/pixhawk-flight-controller-power-recommandations.

   "It is dangerous to power the Pixhawk only from the servo rail, especially with digital servos. Servos may cause voltage spikes (as shown on illlustration below that shows the servo rail voltage on an oscilloscope when a single digital servo attached to a Pixhawk is moved rapidly ). The key thing is that the digital servo causes the voltage on the rail to rise above the critical 5.7V level. Above that level the Pixhawk power management will cut power to the FMU and the Pixhawk will reboot. If that happens when flying you will lose your aircraft."

1B.  Use a buck converter set to 5v (I've used these for years without a failure) and run that directly off  the battery and then output 5v to the rails like in "A".

1C.  Use 1B / buck converter to rail for back up  BUT  use a 5v source from the Trooper PCB as described above (1A)  and run the positive / negative lines into main Pixhawk power connection on the bottom left to pins 1 and 5.

Normal Operation Maximum Ratings
Under these conditions all power sources will be used in this order to power the system.
Power module input (4.1V to 5.7V) [refers to the voltage coming into Pixhawk from the power module]
Servo rail input (4.1V to 5.7V)
USB power input (4.1V to 5.7V)

From the instructions on using a 6s battery 

https://pixhawk.org/users/tutorials/pixhawk_6s_mod

The power port is a so-called DF13 connector with 6 pins.

The six pins of this connector are assigned in the following order, starting by the red wire on the leftmost pin:

1-Vcc (5V input)

2-Vcc (5V input)

3-I (Battery current measurement analog voltage input)

4-V (Battery voltage measurement analog voltage input)

5-Ground

6-Ground

and in their diagram they say you can use an optional bec and run the Positive 5v  into pin 1 and negative into pin 5 on the power input.   

In other words, I'd power from a buck converter output 5 v into pin 1 for power and 5 for ground.  I'd have nothing on ports 2, 3, 4, & 6 resulting in no voltage or current data to the Pixhawk. 

Will the Pixhawk operate ok this way?  Do I need to make some changes in the firmware settings?

Question 2.

Can I safely use my other Pixhawk module that has the gps connector torn off the circuit board. I've tested it and it fires up, but haven't tried flying.

I found documentation on hooking up a 2nd 6 wire cable to comm 4/5  (without mag) 

http://planner.ardupilot.com/wiki/common-installing-3dr-ublox-gps-compass-module/

I am wondering if I could connect my gps into the com 4/5 and connecdt the mag into the i2c connection and then make proper entries in the firmware. 

Any ideas, warnings, or suggestions on if this will work.    To the eye, the only damage to my original Pixhaw is the gps pulled the socket partially off the circuit board and I pulled it the rest and then just bench  tested the board. 

If I can use my orig Pixhawk, I'd do 30-40 flights with no camera or gimbal to test it out. 

I will give out a preliminary Thank You to anyone who has ideas or can help.    Running out of time and I need to decide today if I'm going to tackle my Pixhawk on the new buiild with 6s.

Last question.  Since Pixhawk is getting more popular and stable, why hasn't 3DRobotics come up with a power module and instructions for 6s? I called them today and they wouldn't help saying 6s is unsupported.   I and many others are going to builds with 6s batteries for the longer flight times and with more weight which flies better in wind IMO.