Compatibility of my quadcopter build

Question

I am building my first quadcopter and have multiple questions. I am using a Crius MWC Multiwii SE 2.6 flight controller which will get input from a Raspberry Pi Zero. I have this 4in1 ESC and this PDB. The battery is LiPo 4S 45C 1550mAh.

1.) Since the 4in1 ESC has one output for each of the 4 motors. Can I connect these to the corresponding inputs on the MultiWii that would normally be used if I had 4 separate ESCs? When using 4 separate ESCs each would have additional Ground and Voltage which would be missing when using the 4in1 ESC.

My idea was to connect the 5V input and GND of the MultiWii to the PDB but I am not sure if this will suffice in powering the entire MultiWii. I want to connect the Raspberry to the MultiWii via TX/RX Pins, same question as as before: Do I need additional GND and 5V here if I connect the entire Multiwii to the PDB?

2.) I wanted to connect the Pi Zero also to the PDB. I read that its more secure to use PWR USB port. I am thinking of sacrificing an USB cable and soldering the ends to the PDB. Is this really more secure than using the GPIO Pins and can I power both, Raspberry and MultiWii through the PDB?

Thanks in advance

Answer 1

1) you 4in1 ESC as 3 outputs per motor and 1 input per motor... Your description of the brushless motor seems very confused. Brushless motor are commanded with 3 phases, theirs switching patterns makes the motor turn.

1b)Concerning power you need to check what the PDB specification are for its 5V line, if the current supported is high enough you can power both our multiWii and the Pi.

2) the usb line as some kind of regulation and fuse that the GPIO doesn't have, see https://raspberrypi.stackexchange.com/questions/1617/how-do-i-supply-power-through-the-gpio

Answer 2

1. You can think about Your 4in1 ESC as 4 separate ones. You just have to connect four signal pins to the corresponding signals in the flight controller, as You said. Mind that three signal cables have one pin connectors, that go just to signal pins of your flight controller, whereas fourth one is a three pin connector with second pin missing - this one has the ground connection.

2. Yes, you should connect USB power rather than direct one. USB input is better filtrated, therefore it will be more secure for Your application than direct powering the Pi (see N. Staubs answer). It will be also easier to unplug in urgent cases, rather than directly soldered cable to the Pi.
   BEC installed on Your PDB is capable of supplying 5V @2A. It should power Your configuration without a problem.