I am 16 year old boy and this is my first instructables.So,sorry for my mistakes and off course for my English as well.
In this instructables I will show you how to make a quadcopter based on multiwii firmware and Arduino.all required files are added below.
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plzz vote me for contest thnx
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let's start.

Step 1: Gather Parts

for this instructables you will need some parts.
Arduino (328p)//I am using Arduino nano.
SENSORS
gyro(I am using 6050 as it has accelerometer as well)
pressure sensor(I am using bmp180)
magnetometer (I'm using hmc5883l)
lipo battery
brushless motor
escs(simonk firmware is good and cheap as well)
transmitter and receiver 6ch(I'm using fs-ct6b)
10" propellers x 4
450 quadcopter frame (or you can make your own)

Step 2: Flight Controller

it is not big task.
You just have to connect SDA of all sensors to A4,and SCL of all sensors to A5.and vcc and gnd to Arduino's vcc and gnd.

MOTOR PIN
D3-1st motor
D10-2nd motor
D11-3rd motor
D9-4th motor

OUTPUT FOR RECIEVER
D2-pitch
D4-Roll
D5-throttle
D6-yaw
D7(Aux)

you can make your flight controller on perf board as I made
or
you can fabricate your own PCB.

Step 3: Programing Your Flight Controller

I'm using multiwii 2.4 quadcopter firmware.
download Arduino IDE if you don't have it right know from its original website.
now , download multiwii quadcopter firmware get it from GitHub.
open multiwii.ino file in Arduino IDE .
goto config.h,then
uncomment the type of quadcopter (in my case x type).
find#define 1000000l;
and add // before it
and uncomment #define 4000000l;
now change max throttle to 2000
and min throttle to 1064( if you are using simonk)
At last uncomment all sensors you used( for BMP 180 uncomment bmp085)
now choose your board .
and click upload it.
?

Step 4: Configuring Fight Controller

open the folder you have downloaded
goto multiwii_conf
and windows 32bit
at last click.exe file to launch GUI
now select the com port .
and click start
it will show reading from sensors
click calib acc to calibrate accelerometer(quadcopter should be on levelled surface)

and calib mag to calibrate you magnetometer.

you can further explore the GUI .

Step 5: Power Distribution Board

it is very simple to make just draw two rings on copper clad by marker and solder all +ve wires to one and -ve to another.

Step 6: Last But Not Least

connect your motors to flight controller as described in step 2
connect flight controller to receiver again described in step 2
connect battery to flight controller.
now your escs will start beeping.
now turn on your transmitter and arm your quad buy yaw stick move it down and take I to extreme right.
motor will start moving now .

Step 7: Troubleshooting

if it is not arming
check the minimum and maximum value goes by your transmitter ,it should be less than 1050 and greater than 1900).
if it is not flying properly
you must change its pid tuning.
thnx for reading my instructables

don't hesitate to put question just post them in comment.
plzz don't forget to vote me .
again thnx