Out of the box
This product is obviously trying to look like a Naza-M but first impressions were not so good: even the external finish of the unit and the quality of the accessories are way behind the offering from DJI. It is clear that the main-controller and the GPS ‘puck’ have both been designed to mimic the Naza-M although I noticed the GPS module only had three wires which would lead me to believe it is just a GPS module with a serial interface and no internal compass (we’ll come back to this).
Beneath the shiny plastic
It would be rude not to have a look inside: first of all I opened up the GPS module to see if my theory about it having no compass was correct.
The first thing that I noticed was the terrible soldering on the wires (everything else was pick-and-place / machine re-flowed); the insulation was melted and there was a blob of solder between the signal wire output and two other components (a resistor and a voltage regulator). As I’d spotted this fault I decided it would be best to correct it before reassembling the unit other-wise it was more than likely going to fail when I powered it up anyway! (While re-soldering the wires I also added some heat-shrink to help support the wires and prevent them fraying).
What! No external compass?
The GPS module its self is a UBLOX NEO-6M (see photos), these modules are GPS only (no compass) and there was nothing else on the GPS board that resembled a 3-axis magnetometer chip (compass) so we can only assume the compass is housed in the main-controller and the forward arrow on the GPS puck is just there purely for show!
You’re probably thinking why is an external compass so important and what’s the issue if its housed inside the main controller? Its simple really; a compass works by detecting the presence of magnetic north of which the magnetic field can be pretty weak so ideally you want to have a clean ‘view’ of magnetic north and be as far away from other sources of magnetic interference such as motors (which contain many magnetic poles) and current induced magnetic fields (such as those from wires and PCB multi-copter base plates). This is why having the compass mounted above or below your multi-copter is generally advised and the worst place possible would be right in the middle of your multi-copter frame.
The components were all appear to be fitted by a pick-and-place machine and the soldering (apart from the joints between the main board and the smaller PCB’s housing the connectors) was also machine re-flowed so that’s a positive, there appears to be what resembles a Honeywell magnetometer (compass) chip on the base PCB of the main-controller which would confirm the GPS unit is just for GPS which is a bit of a disappointment (one of the benefits of the Naza-M is the compass can be mounted up and away from the motors and frame).
I was actually surprised to find a proper barometer on this controller, but none the less there it is hiding just below the top PCB and beside the IMU daughter-board (in the photos below). So there will be no excuses for it not to have a pretty decent altitude hold function.
We can also see more evidence that shows it’s definitely no Naza-M clone, the Naza uses a quite impressive ARM Processor, I couldn’t quite work out what this unit uses but I’d guess its an ‘alright’ ATMega based processor.
As with the Naza the IMU’s are housed on a dampened daughter-board however it doesn’t appear to be anywhere as near complex (the Naza-M has a 14 wire ribbon cable going to the daughter board).
Thoughts so far
I will be fitting this flight controller to a DJI F450 RTF kit in the next part of this review so I can’t comment on how it flies (yet) but based on the build-quality and the components that have been used I’m not expecting any miracles!
NOTE: We never did carry out a flight test as we could not get the system to work reliably and we didn’t want to wreck an air-frame just for the sake of it.