Pixhawk LITE mini pixhawk clone - RC Groups
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May 20, 2015, 06:49 PM
Wisconsin
Mini-Review

Pixhawk LITE mini pixhawk clone


Quote:
************************ Notes or errors and omissions **************************
I started this thread a year ago. So be advised that although there is invaluable information in this thread the manufacturers can and have changed the product over time. Hence although I am not aware of it as of Jan 2016 they could someday fix the problems making the information here on page one obsolete. If you receive a board that does not seem to fit the data send me a PM and I'll update page one.

NOTE There was a version one of this board that had the power module pins backwards. You can not use a "normal"power module cable with that early version. The current verson GLB is calling V2. They fixed the power module connector. It now conforms to the Pixhawk standard. But all the other problems talked about below still exist.

Whomever created the pinout pictures on the GLB website got a number of things wrong, at least as of this date. Hopefully they will correct it.
The order of many of the pins are backwards from the same connectors on the 3DR Pixhawk. See the drawing labelled "corrected" for the actual pin-outs.

Since the I2C connector is backwards, but there is an expansion board for more than one I2C device, (I2C devices are compasses, LED external lights etc) jesmail suggests using a reverse cable from the Pixhawk LITE I2C port to the I2C expansion board. This has the effect of fixing the problem so all the devices you plug into the I2C expansion board can then use normal pinout cables. So fix it once and then all your I2C add-ons will be correct.

I have discovered the GLB provided diagram of the bottom view servo pinouts is backwards and the grounds for the servo connections are down the reverse of the full sized Pixhawk. I have created a corrected diagram. Note the view is from the "TOP" side of the board with the Pixhawk LITE name not the "bottom" with the USB connector as the GLB drawing.


The next problem our sloppy designer created: The board has two combination GPS/Telemetry connectors. Normally for serial communications you have a pair of wires the Transmit (TX) and the Receive (RX). You normally need to connect a transmitter from one device to the receiver of the other device it is communicating with and vice versa. So TX>RX and RX>TX from either devices point of view. So your GPS1, for instance, has it's TX wire going to the GPS1/Telemetry1 connector marked RX ( on the GPS side of the connector) and the GPS1 RX wire needs to go to the GPS1/Telemetry connector pin labeled TX. GPS1/Telemetry one has it's TX/RX backwards but GPS2/Telemetry is NOT backwards. Check the corrected drawings below. Note these connectors share pins for the GPS and the Telemetry.

The telemetry pinouts are correct. You need to share the 5v and ground connections between your gps and telemetry cables.

I have included the pinout lists for the 3DR Pixhawk, see full attachment below for reference so you can compare.
************************************************** *************************************
Pixhawk Lite (2 min 44 sec)


Having built a variety of multirotors based on Arducopter I have to say I like the small mini versions because they make it easier to fit everything in limted spaces. With the end of life of APM many people have been waiting for a mini Pixhawk.



There have been small Pixhawk compatible boards before this including the Virtual Robotix micro Brain
and the AUAV -X2.



But the new GoodLuckBuy Pixhawk LITE breaks the price barrier at $63.27.

I received the Pixhawk LITE after a 15 day delivery from Asia.

The board came with no documentaton. There is a connector diagram provided on GLB's website(this diagram has numerous errors). But this clearly is not going to be designed for the new builder. Hopefully most of the details are the same as the full sized Pixhawk.

The mounting holes appear to be 30x30mm spaced.

One of the changes to the Pixhawk LITE to fit in the small form factor was to remove a couple of connectors found on the full size Pixhawk.
They are the Speaker/DSM, Buzzer, Can bus, SPI and the external USB ports.

Mine came with a I2C expansion board to help make up for the reduced number of I2C ports. A PPM encoder board for users that want to use PWM output receivers.

It came with a set of cables and the ARM switch.




I powered up the board by plugging in the supplied USB cable and .... nothing. I made sure my connections were good but nada. So I replaced the USB cable with one of my own. Both APM and Pixhawk boards I have used are very touchy about the USB cable that work. I was amazed to find that indeed changing a perfectly good USB cable out with another can make a difference.

So it did. I was able to power up the board and connect it to Mission Planner. First note is that it came loaded with 3.3 Dev firmware. I found this curious because the current stable release is 3.2.1 not 3.3. It appeared to work fine though. I then loaded 3.2.1 and rebooted. I got a bad gyro health message on the HUD. I proceeded to do an accelerometer calibration and a compass calibration without issue. But the Bad Gyro Health message remained and the updates in Mission Planner were quite slow, abnormally so.

I then installed beta firmware 3.3 rc4 and rebooted. No bad gyro health message. I then did the calibrations and the board seemed fine. To verify the test I returned the board to 3.2.1 and the bad health message returned. Then back to 3.3.rc4 and it was gone.

My conclusion is that the board needs something fixed in 3.3 and that is why they delivered it with a beta version of the firmware.

So far so good tho and I am looking forward to a low cost replacement for my APM controllers that will bring all my multirotors up to the 32bit track.

I like using stable versions of the Arducopter firmware, so it is troubling that it seems to require a beta firmware to operate correctly. But 3.3 will probably be released soon so maybe this is not an issue.

But a flight test will be the clincher.

Cheers

Note all the attached tables of pinouts are for the full sized Pixhawk by 3DR. My corrected pinout images of the Pixhawk LITE are labeled CORRECTED. The other similar images are the ones provided by GLB that are incorrect. There is a general setup guide for Pixhawk in the attachments courtesy of Gervais.
Last edited by mike_kelly; Apr 07, 2016 at 02:40 PM.
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May 21, 2015, 10:56 AM
Wisconsin
Quote:
Originally Posted by nanorapture
thanks for the review and pics.

do they provide 8 wire cables for the 6 pin dual ports, i.e. with two vcc and two ground wires split off of the two pins?

Looks real good!
No, you would have to do the doubling up external to the connector. I think the connectors are pretty small to have two wires on one pin unfortunately.
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May 21, 2015, 02:23 PM
Constantly Confused
nanorapture's Avatar
Quote:
Originally Posted by mike_kelly
No, you would have to do the doubling up external to the connector. I think the connectors are pretty small to have two wires on one pin unfortunately.
They are also unfortunately too small to solder comfortably as well, but I usually end up making custom cables for all my copters anyway. I splice my small wires together end-to-end with a small soldering tip and 2mm heatshrink.

After you loaded AC 3.3 and did not get a gyro warning, did you check to make sure ARMING_CHECK is actually enabled? The arming check error discrepancy between AC versions is strange .

Thanks again for the scoop Mike.
May 22, 2015, 09:44 AM
Wisconsin
Quote:
Originally Posted by dbrowning
What's the difference between APM and pixhawk? It looks from what I've read that pixhawk is more modern hardware, am I on the right track?
The major difference is that the APM is based on an 8bit processor and the Pixhawk on 32bit proc. There is also more memory on the Pixhawk. Hence the developers ran out of resources on the APM hardware to continue adding features.

It still is a fine platform doing what is does currently and with quads or hex but with an Octo or more advanced features it falls down.
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May 22, 2015, 01:35 PM
Registered User
scoopdreams's Avatar
That's a very small board... Thanks for the review subbed. It's a shame canbus has to go though because with 3.3 canbus support is full fledged - just waiting for the peripherals now. How many outputs does this have btw?

And very cheap too!

Edit: just reread the description and saw it have full output complement. another important question then: Is this board using the accursed df13 connectors or standard micro molex?

Edit2: looked closer at your pics - standard molex Yay! Ordering one now thanks for the tip off!
Last edited by scoopdreams; May 22, 2015 at 01:46 PM.
May 22, 2015, 03:42 PM
Wisconsin
Quote:
Originally Posted by pieri70
Hello
me too I'm interested in this FC, I'll put my APM on my Bixler aeroplane to try Arduplane and use this for my 550 quad..
What do I need to complete this board? I mean Which GPS? Does it need Power module as it's fot APM?
Buzzer? External led??
Tanks everybody
Just like a full size Pixhawk. Same GPS options and same power modules. But no buzzer port.
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May 22, 2015, 06:58 PM
Wisconsin
Quote:
Originally Posted by balbs
How's the board's build quality in general?
It is not bad. The soldering is good and even. The connectors are on straight and not crooked.
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May 22, 2015, 07:08 PM
Wisconsin
Quote:
Originally Posted by dbrowning
Ok, thanks. So what sort of features would you not get with an APM board as opposed to a pixhawk? I'm just wondering if for a hex I'd get what I want from APM.

Am I right in thinking they run the same firmware (all be it for 8 bit and 32 bit systems) and you use the same software on a laptop to configure things? If this is the case then I guess the pixhawk will process things more quickly and be able to cope with new features that will be released in the future.
Yes the APM has had the same firmware path with Pixhawk. But that ends at 3.3 where APM stops and Pixhawk goes on.

Some of the features are subtle. The APM does a fine job even with my hex. But the Pixhawk uses the EKF (Extended Kalman Filter), Spline curves for Auto Mission etc. These types of things are not killer features but they are examples of future refinements that require processing power. For me I think the reliability features are more important. We need to move out of the hobby basement and start making machines that can do work. The Pixhawk allows you to have two GPS receivers. It will watch the quality of the signal and flip back and forth using which ever unit is receiving the best signal. I think a lot of flyaways and oddities are due to GPS Glitches. If you look at a log of a APM flight the satellites are changing all the time. Some rise and some set and some go behind that barn. Having a backup Satellite receiver is important for the reliability of Loiter and the other GPS dependent modes.

So I think reliability is probably my number one motivator to go to Pixhawk.
Last edited by mike_kelly; May 23, 2015 at 09:13 AM.
May 22, 2015, 09:23 PM
Constantly Confused
nanorapture's Avatar
Also, the Hawks have multiple independently configurable serial ports and usb, where as the APM boards have just 2 serial ports shared with the USB.

I am putting together an APM antenna tracker with this hawk board as the controller with telemetry in and out, and the APM boards just won't cut it. More ports is better maties!
May 23, 2015, 09:07 AM
Wisconsin
Quote:
Originally Posted by pieri70
What is for the SPI port? and CANBUS?
I2C, SPI and Can Bus are all serial interface network protocols. They are a way to allow communications between multiple devices and by devices I mean chips on the circuit boards. They are used on the flight controller boards to let the microprocessor communicate with the other devices on board.

Each protocol has features that some people would like to use to improve the flight controller. Currently the I2C bus is used to communicate between the microprocessor and the compass module on APM boards. The SPI bus exists on APM but is not used to communicate with external devices. Can bus is new on the Pixhawk. DJI uses Can bus for it's pheripherals.
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May 24, 2015, 09:45 AM
Registered User
scoopdreams's Avatar
Quote:
Originally Posted by mike_kelly
Ah, I see what you mean. I was not looking at their cables but in the standard cable supplied with the PM, since I was trying to swap out into an existing build. I'll have to ring out that cable and see if, since the red marker is reversed if the two center conductors are correct, as you noted. Then check all the rest of the cables. I had assumed they were all straight through but that was a bad assumption
Thanks for the review and all those catches though, do keep them coming! Really appreciate it as I do think the current pixhawk is big enough to cause trouble fitting onto certain crafts. This is a pretty good alternative not to mention the price.

Could I bother you to check one more thing? Pixhawk currently has two onboard IMUs, does the Lite also have two IMUs? Either look for the chips (I believe it's the MPU6000) or after you calibrate accel does IMU1 and IMU2 values get populated? Thanks!

Edit: I see one invensense mpu6000 on the bottom in a corner in your pics but can't seem to find another. This is another worry point as with EKF they allow for better stabilisation with two or more IMUs.

Do help check as they might be using another IMU that's not the mpu6000 as the second imu.
Last edited by scoopdreams; May 24, 2015 at 09:57 AM.
May 24, 2015, 01:16 PM
Wisconsin
Quote:
Originally Posted by CBRrunner
is the mounting spacing the standard 35mmx35mm like the micro apm?
The hole spacing is 30mmx30mm.
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May 24, 2015, 01:41 PM
Wisconsin
Quote:
Originally Posted by scoopdreams
Not good observations skills, just spend way more time than I should scrutinising photos hah.

Anyway mate, I couldn't find any info on the chips too. Maybe when you do your accel calibration see if the imu2 values get populated too and let us know. I'm hoping it has a second imu but if not, this board will still be good for planes, smaller multis, rovers, or as above mentioned an antenna tracker. Without the second imu I'm a little hesitant putting it on a big bird.
Well the ins_acc and gyro are all populated, the acc2 and gyro2 are populated but the acc3 and gyro3 are zeros.

Can the one 6000 be dual?
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May 24, 2015, 08:32 PM
Wisconsin
Quote:
Originally Posted by CBRrunner
If you connected tx to TX doesn't that make one of them an rx?

I thought this thing ran the inputs through sbus?
Always you connect serial connections with a Transmitter connected to a Receiver. So with serial GPS connections you commonly connect the tx line of each side to the Rx of the other side. But in this case, ether by mistake or purpose, they have "pre-crossed" the lines in their diagram by notation. So yes the ones on the Pixhawk LITE are actually once again backwards.

As far as the receiver input PIxhawk can use either sBus or PPM. I use PPM.
Last edited by mike_kelly; May 24, 2015 at 08:46 PM.
May 24, 2015, 08:35 PM
Wisconsin
So I have good news and bad news.

I got my receiver PPM input working! I can cal the radio.

The bad news? The reason it was not working is that the bottom view diagram from GLB is once again backwards.

Unlike the 3DR Pixhawk the servo connector signal pins are topside and the grounds bottom side. This is the opposite of the real Pixhawk.

Corrected diagrams on the first page.
Last edited by mike_kelly; Jun 04, 2015 at 05:33 PM.

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