Pixhawk 2.1 or Pixhawk 4

Hi everyone.
Actually I need a suggestion.
So I am going to assemble a hexacopter (the hmf s550 frame (not the dji f550 frame)) but I am not being able to decide which flight controller should I use - the pixhawk 4 or the pixhawk 2.1
So let me summer up what all I will be adding to it

  1. 3-axis gimbal
  2. Rplidar (allows 360 degree obstacle avoidance)
  3. 2 lidars at the bottom and top of the hex
  4. TBS Crossfire or OSD
  5. An RGB LED module
  6. 2 FPVS (2nd one is a very cheap camera without gimbal)

You need to look at what interfaces you need for the peripherals, and use that information to inform your decision.

I actually am just taking suggestion because both will work for me.
But the question is should I go for more price which has much more compatibility than I want.

I’d go a Cube, because the pdb for the PH4 is just annoying. But PH4 has an exposed SPI, and the Cube doesn’t.

What can happen if I have an exposed SPI?

That’s why I asked about the interfaces for your peripherals. It is just another bus standard.

RPLidar A2 :- http://ardupilot.org/copter/docs/common-rplidar-a2.html
2 benwake mini lidars :- http://ardupilot.org/copter/docs/common-benewake-tfmini-lidar.html
TBS Crossfire (requires 1 telemetry port)
Bluetooth module hc 05 (can require serial connection but i was thinking about a can bus connection)
Landing gears (aux2)
external leds (i will power with bec)

Tarot 3D V Metal 3 axis PTZ Gimbal for Gopro Hero 5 Camera Stablizer TL3T05 for FPV Drone System Action Sport Camera


5.8G 600mW 48CH Wireless AV Transmitter and Receiver TS832 RC832 RC832H

Thieye T5e is my camera and a local camera for 2nd fpv
I a using an fppv splitter/controller
Houbbywing XRotor 40 A escs and taranis qx7 with the x8r
HMF S5550 frame
dji b2212 motors
that is everything i will use in making that drone
oh btw i have thought of using i2c splitter as a can hub to use lidars and bluetooth plus i had thought of using 2 gnss units but if you say pixhawk 4 and if i am left with an extra can port i will use it for the 2nd gnss i know how to
Sorry for any grammar mistakes pls just avoid making fun of me

Oh yeah plus I have found more options:
pixhawk 3 pro
Pixhack V5 the clone of pixhawk 2.1
Pixhack V3 the clone of pixhawk 3 pro
I can’t buy the pixhawk 3 pro as it is unavailable

I’m not going to make fun of you! It’s great that you are asking questions.
FYI the CUAV V5 and V3 aren’t clones of anything, except perhaps aesthetically. They’re actually very good flight controllers, and like the Pixhawk2.1/Cube would be suitable for this build.

Lets go through your components, and how they connect to ArduPilot.
RPLidar: this uses a Serial protocol, and despite what the wiki says please power this off it’s own bec.
Benewake TFMini: these also use a Serial protocol, unless you follow the guide from Patrick here: How to make the TFMINI rangefinder talk I2C. In your case, I’d recommend you consider doing that. I’m guessing you want these for up and down distances?
TBS Crossfire: Serial if you intend to use it for mavlink/telemetry as well as control. I haven’t used these, but make sure you research how to set them up before buying.
Bluetooth HC-05: This is a serial device. You can’t use it on CANBUS unless you develop a whole bunch of stuff yourself - not a beginners project in my opinion.
Tarot Gimbal: that particular one can read SBus, so if you can figure out channel assignments I’d suggest setting it up on the SBus-out port to save wires.
ESC’s: these are standard PWM escs.
RC: again, pretty standard. FrSky has performed well for me. Interesting that you’re looking at both Crossfire and FrSky though. Have a think about what you are trying to achieve.
The video stuff is pretty standard, and doesn’t interface with ArduPilot (with the setup you’ve described, anyway).
This adds up to five serial device, plus you’ve indicated you would like two GPS’s

I have 4 recommendations.

  1. Consider converting the TFMini’s to I2C, as per the guide I linked.
  2. Consider writing down the influencing factors behind your telemetry and RC choices. They are both products with good reputations, but not a common combination.
  3. Consider UAVCAN GPS units. If you don’t convert the TFMini’s to I2C, you’ll have to do this as there aren’t enough UART’s for all the serial devices.
  4. Put Bluetooth on a serial port.

I hope this helps.

Hi so I get what you are trying to tell me
But I know a lot of things you have just said (just to tell you I am not a newbie)
But you told me to reconsider about the TBS Crossfire and Frsky Taranis QX7S
I just want you to take a look at this video by Painless 360
Click Here!
I just wanted to inform you about everything so you could help me choose which version I should buy
And thanks for that i2c thing with the smaller lidars. Very helpful!
Lastly can I connect the rplidar also through the i2c thing using am Arduino because then ic ANC onnect the Bluetooth if not then also it doesn’t matter
I have one telemetry port at least for the crsf
Anyways now all that is sorted out could you just help me choose now
What should I go for
Pixhawk 3 pro (means pixhack v3) (cuz it isn’t available)
Pixhack V5 (if the cube and this have the same type of stability)
Or Pixhawk 4 from holybro
Or Pixhawk 2.1 the cube
Lastly I just want to tell you
I am ordering from AliExpress and the pixhawk 2.1 costs like 40,000 INR which is too much for any fcs
And the others cost like half of that amount and I have a budget and with pixhawk 2.1 it is crossing that budget so should I go for the cube of the PX4 OR PIXHACK V3 OR V5

I told you to reconsider using frsky for RC, and having Crossfire, because you said “taranis qx7 with the x8r”. I just don’t see the point in using the X8R when you have Crossfire.

All the controllers you’ve listed will do fine. Personally I think the Pixhawk4 has a very poor layout, so wouldn’t be my choice. If the Cube is out of your project budget, the V3 or V5 are both good choices. I’m not sure the v5 has 5 serial ports: you need to check that.

Re shifting other devices from serial to i2c: I’d suggest not to, just the tfmini’s.



I dont know what you are saying maybe for 16 channels I am using the x8r

I mean I am using it for 16ch

Make sure to get the rplidar A2M8. It works with object avoidance flawlessly on the pixhawk. The A1 had very poor performance for me

Umm the A1 is good too people have used it but many prefer the A2.

Oh btw I found this uart port on the V5 so that means I can connect the Bluetooth thing to it right

If it has enough uarts, the v5 is a good choice.

Thx for your help guys I might post a seperately forum fort his build to help other thx for the help

*I might post a seperate forum for this build

*to help others and thx for your help
Uggh i hate typing on my phone