Review & test of Gearbest's Pixhawk and comparison with 3DR's Pixhawk

Recent 3DR's move not to sell DIY components & parts anymore, pushes hobbyists and prosumers to diversify their supplier's sources.  Like many others in the community, my issue is to find an "as good quality as 3DR" alternative for a Pixhawk board.  I started looking around for possible 3DR Pixhawk replacement candidates, with a quality I can trust in my builds. 

There exist myriads of different "Pixhawk" equivalent boards. Most of them are not direct drop-in replacements as they are equipped with different connectors and have different sizes and shapes. Furthermore, most of them do not share the same quantity and redundancy of sensors (i..e.: two gyro, two accel, compass, baro, etc). A direct drop-in replacement is essential for prosumers and professionals trying to standardize parts, connections and components to a maximum.

Then, I was kindly requested by Gearbest to review some of their new FPV racer quad; offer which I declined being a very poor racer pilot (wouldn't have made justice to their fpv quad), proposing them instead to review their Pixhawk board which looked to be an exact match for 3DR Pixhawk board on all aspects: schematics, size, shape, connectors, etc.

This is what this video is about : a test, review and comparison of Gearbest's Pixhawk (versus 3DR's Pixhawk).

Hope this will provide some useful info for who's looking for Pixhawk flight controllers.

Cheers,

Hugues

Views: 5916


3D Robotics
Comment by Chris Anderson on May 16, 2016 at 10:46am

Great work on this. Thanks for doing and sharing!


Admin
Comment by Thomas J Coyle III on May 16, 2016 at 10:54am

Here is a link to Gearbest's, which also sells home and gardening products, Pixhawk webpage.

Regards,

TCIII AVD 


Developer
Comment by Andrew Tridgell on May 16, 2016 at 1:17pm

thanks very much for this, much appreciated!

I was a bit concerned about the 72MHz part for the IO processor. I was concerned it may impact on up_udelay() which tries to delay by given number of microseconds. The code currently assumes 24MHz:

https://github.com/ArduPilot/PX4Firmware/blob/master/nuttx-configs/...

looking more closely at your video you can see it still has a 24MHz crystal, even though the part can do 72MHz. So it is probably absolutely fine. I also checked with David Sidrane and he also thinks it will be fine.

If you wanted to test up_udelay() and make sure it really is getting the right delay that would be a nice thing to do, although the fact that it boots is probably a good indication.

Of course, you could also ask them to send me one and I'll do some sw tests on it :-)

Cheers, Tridge


MR60
Comment by Hugues on May 16, 2016 at 1:42pm

Thx Chris, Tridge. Thx for the info about the  24MHz frequency. I will surely test it runnimg with Ardupilot code. How could I test the updelay function?

Comment by Ben on May 16, 2016 at 1:49pm

Very nice review, just a suggestion for the power supply ripple amplitude and frequency measurement : an oscilloscope would be useful for precise measurement. (I'd be surprized if their switching frequency was in the 7 kHz range as shown on the multimeter, most small switching supplies are today in the hundreds of kHz or MHz range.)

Comment by Gary McCray on May 16, 2016 at 2:19pm

Nice Job,

This is a great idea.

Now that 3DR has moved on, it does leave it to us to figure out what does work and what doesn't without any further real or imagined proprietary concerns.

Several of the Devs have already been working with various manufacturers boards such as the Pixracer both on firmware patches and with the makers themselves to permit compatible operation.

But the fact is that it would be very worthwhile to have simple independent verification of the functionality or lack thereof of the growing number of true Pixhawk clones that are now turning up.

In the past there was reluctance to do this because of a perceived violation of the heavily invested parties (3DR's and possibly ETH's) rights (and investment) being trampled on.

But as it stands now, we are really much more on our own and need to get on with it.

Best Regards,

Gary


Developer
Comment by Andrew Tridgell on May 16, 2016 at 2:29pm

@Hughes, just change the main loop on the IO chip to blink the blue LED with a delay controlled by up_udelay(). I'm pretty sure it will be right, but if you want to check it I could give you a test fw.

Also put a logic analyser on the IO pins and make sure you get the right PWM pulse widths and period.

Comment by DG on May 16, 2016 at 5:51pm

Pixhack seems to be quite popular. I have one, but it seems like I unplugged the main power connector and it shut down with backup power connected; haven't verified that. 

Comment by Mauricio on May 16, 2016 at 8:32pm

can anybody say when 3DR will stop selling the Pixhawk? killing a business unit that works looks like a very unwise decision


3D Robotics
Comment by Chris Anderson on May 16, 2016 at 8:54pm

We're not stopping selling Pixhawks! I have to say this every week here, so I'll do it again: We're replacing Pixhawk 1 with a new, improved version in a month or so. I'll say it again: We are improving Pixhawk, not halting it. 

Why do people find this so hard to understand?

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