MultiWii Flight Controller logic-level is 3.3v?

M

miky94

Well-Known Member
I'm using a Raspberry to control a MultiWii Flight Controller V2.5 by using this FTDI USB to TTL adapter.
I've seen in this instructable they instead just use a cable from Raspberry TX to MultiWii RX, but I'm not sure they have the same voltage because the Raspberry logic-level is 3.3v and I didn't found clarifying informations on if the MultiWii logic-level is 5v or 3.3v.
I'd like to eliminate the FTDI and use just the cable for reducing space and weight.
is the connection in the image right?
 

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--Oz--

--Oz--

Member
i think the fc is 5v, its a ancient processor and firmware compared to the new stuff. for $12 get a stm32 F4 fc from ebay, its 3.3v, run betaflight, be happy

whats the project, got a picture?
 
M

miky94

Well-Known Member
--Oz-- said:
i think the fc is 5v, its a ancient processor and firmware compared to the new stuff. for $12 get a stm32 F4 fc from ebay, its 3.3v, run betaflight, be happy

whats the project, got a picture?
Click to expand...
I chose MultiWii because there is a python library that I use to send RC commands with the Raspberry and all projects of this kind I saw use it, do you know another FC with which I can do this?
 
--Oz--

--Oz--

Member
RC commands are mostly PWM signals, but most new FC use SBUS serial protocol. Its quicker and has upto 16 channels on one wire.

The number one RC signal is PWM, its been around since the 1950's I think. Its simple 1.0ms to 2.0ms pulse width signal. 1ms being left, 2ms being right and 1.5ms being center. These are sent 50~70Hz freq. These will operate almost all servos, they will do some FC, but the issue is more wiring (PWM needs one wire per channel, kinda makes it messy, lol)

These are the most common RC for FC :
SBUS
PPM (CPPM)
PWM

These are not as common:
MSP
SPI
SPEK1024,
SPEK2048,
SUMD,
SUMH,
XB-B,
XB-B-RJ01,
IBUS,
JETIEXBUS,
CRSF,
SRXL,
CUSTOM,
FPORT

F4 ~$14 or less)
F4
https://www.ebay.com/itm/SP-Racing-F4-F ... 0&LH_BIN=1

One simple way to level shift is just using resistor voltage divider to drop the 5v down to 3.3v. EX: 680Ω top resistor and 1.32KΩ bottom resistor.

Can you share a picture of your project? Are you wirelessly controlling the FC though the R-pie, or?
 
M

miky94

Well-Known Member
the python library uses the MSP protocol, I'm using a Raspberry to control the drone from the smarthone.
I'm still working on it but the idea is to build an intelligent drone like the one in the instructable I linked, where it seems that the Raspberry TX is directly connected to the MultiWii RX.
are there python libraries to do that on the F4 ? or are there better FC for this purpose?
 
--Oz--

--Oz--

Member
MSP is simply multiwii serial protocol, all the FC use this, mostly just for setting up through the usb cable and the gui (betaflight/cleanflight/etc), but i guess, you can control roll/pitch/yaw/thro with it, usually that control comes from the receiver.
 
--Oz--

--Oz--

Member
I just looked at the instructables link, I highly don't recommend building a quad with them specs (plastic frame, crappy motors, low end esc). It also looks like he is using a low end normal transmitter/receiver.
 
M

miky94

Well-Known Member
I didn't use those specs.
anyway if all the FCs use MSP I can control all of them with this protocol?
I'm looking for a new FC with these specs:
- cheap
- compatible with the library
- best hovering (immobile, for stable video) and precision of maneuverability
- with GPS functions
can you suggest me one or some (with pros and cons)?
 
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