Holybro Pixhawk 4 vs CUAV Pixhack v5

#1

Hello guys.
I am not that experienced and knowledgeable so could anyone tell me what is the difference between these flight controllers? On the paper they look the same but the biggest difference is the price. So what make CUAV Pixhack v5 so much better that the price is almost twice higher? Specification of the hardware is nearly the same - Main FMU Processor: STM32F765
32 Bit Arm® Cortex®-M7, 216MHz, 2MB memory, 512KB RAM, IO Processor: STM32F100, 32 Bit Arm® Cortex®-M3, 24MHz, 8KB SRAM.
As well on-board sensors: Accelerometer/Gyroscope: ICM-20689, Accelerometer/Gyroscope: BMI055, Magnetometer: IST8310, Barometer: MS5611
I see only difference in interfaces and the structure of the casing.
I am confused because I want to buy some reliable FC for my heavy quad-copter and Holybro has a good price but I don’t know about reliability and as well the power management board is not enough due to current detecting sensor is up to 120A so I guess PCB as well can take max 140A without any damage. But whole package is tempting because you get for smaller price GPS, power brick and some cables and CUAC Pixhack v5 comes naked and price is much higher.
So owners of mentioned FCs please tell me about your experiences and what would you chose for heavy-lift X4 quad which will become sooner or later X8 frame with a weight about 10 kg.
So please advise guys.

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#2

Hi @BUZER,

I don’t know too much about Pixhawk 4 but I just received a Pixhack5. AFAIK the Differences are more likely to find in the mechanical construction. Pixhack 5 has a damped IMU Unit inside the silver cube, while Pixhawk 4 has it soldered on the main logic board.

Pixhack 5 also has a built in RGB Status LED around the Cube and more I2C Connections. I think it is also heavier (90gr) as for the Pixhawk I find very different weight Specs (ranging vom 15gr to 98gr - however the lower 15gr is almost impossible, as a naked mRo X-2.1 has about the same weight with half the size and it does not have any sort of cover).

Pixhack 5 comes with a full cable set, as well as a WiFi 2 Dongle, PowerModule, Usb 2 Serial Board and I2C/CAN Distribution Board, GNSS is optional. I paid approx. 270.- U$ w.o. GNSS.

#3

Pixhawk 4 also has an isolated imu, but it’s a lot less sophisticated than the cuav v5 (PH4 isolated imu is a small pcb on mounting foam, similar to the Holybro Kakute).
Personally I think the cuav v5 is a better board, for a few main reasons:

  1. Servo headers are properly broken out, so you’re not restricted to the bespoke power board.
  2. More peripherals broken out.
  3. More robust case. You can get a cnc case for the PH4, but it’s extra.
  4. Safety switch. Personal preference but I don’t like having the safety switch on the gps. I understand why some might, but I don’t.
    Just my opinion. Others may differ for legitimate reasons.
#4

I agree, the v5 Case feels very sturdy - showed it to some Friends (they fly real Gliders) and they were very impressed by the look and build of the V5.

Thanks @auturgy I was not aware the Pixhawk 4 also has IMU dampening. I think this is crucial, I have a 680 HEXA with the mRo X2.1 and besides i use dampers the vibrations are rather high. So I am looking forward to use the V5 on this Platform.

#5

At the beginning thank all of you guys for participation.
No one said anything about reliability of this FCs. Do you get some problems I mean strange behavior of your RC controlled aircrafts, boats or cars, (mainly I am asking about aircrafts) – flipping, crushing, glitching, falling from the sky  or another problems which can’t be resolved on actual firmware version. As well what about ESC compatibility, are the all ESCs compatible with this FCs or you found some trouble with running for example BLheli_32. Are they supporting Dshot1200 and telemetry from ESC on actual FW version? And what is the frequency range to control ESCs on the servo rail? Is it restricted to 400MHz like on the older Pixhawks?
I am still confused which I should chose. I just don’t wat to crush my custom made carbon fiber frame which cost me a lot of my time, efforts and money as well.
As I said Holybro has a big advantage for me which is better price and 8-16 PWM servo outputs (8 from IO, 8 from FMU) so please give me something witch make Pixhack v5 so superior to compare with Pixhawk 4.
And as well what is the type of cable connectors for Pixhack v5, I can’t find it anywhere.
Thank you in advance for your help.

#6

They both use jst-gh cables.
I haven’t seen any reliability data comparing the two boards, so can’t comment on that aspect.
Regarding DShot, they are both capable of the protocol but the PX4 firmware isn’t. Same re 400Hz update rate. This is a PX4 limitation, not a hardware constraint.

#7

I had RMA with one controller. Excellent Service from holybro.

#8

I think everyone is forgetting one huge point here. The level of development testing and what went in on the frontend and background through the release. There is no comparison from that perspective. The Pixhack v5 had a very limited release of beta units to only several developers right before it was commercially available. The Pixhawk 4 has been in many iterations with developers for months, probably closer to a year. Do i like the custom power board on the Pixhawk 4? No, it’s not even the same form factor and the breakout board for the pins is useful only if you do some planning. As a drop in replacement it can be a pain. As for an isolated or suspended IMU, more often than not this can be problematic which is why a vibration study (and its’ results) should be published (they did one for the Pixhawk Cube), to understand truly if and to what extent there is a benefit (and at what frequencies). So, reliability? Pixhawk 4 all the way, it’s what developers are using and so will always get things tested against. Pixhack v5 is just the Pixhawk new red cube, just released with unknown testing behind it before the actual Hex Red Cube is released (and it’s rumored the Red Cube will use an H7 processor anyway which would be more advanced). I wouldn’t use the Pixhack in any new builds till other people crash them first and say why. My 2 cents.

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#9

I have purchased 2 PixHack V5s and am very pleased with the overall product and customer service provided by CUAV. (do not get the knockoffs). I have one in my Tarot 680 Pro and the other in a Hover 1. They come with all the cables, I2C replicator and debug cable. I am currently in verification mode flights and they are both operating flawlessly. The overall quality of the product is noticeably better even when replacing my DJI N3 (except for the cables of course).

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#10

I have already purchased the pixhawk 4 from Holybro so I will test it on my newly builded quad x4 and later x8 as I mentioned. Like Flying_Forfun said, pixhawk 4 is longer on the market and people has been testing it since then. So that reasonable way of thinking to fly safer with FC which is exercised more by people than Pihack V5.
auturgy said IMU on the pixhawk 4 is isolated on some kind of foam due to that, are the vibration dapers neccesary to fix Pixhawk 4 on the frame? Has anyone experience with flying with or without the vibration dampers? Is there any difference?