Flying BeagleBone Green

20911Published On May 14,2016 18:18 PM

introduce

Step by Step Introduction

STORY

About BBBmini

BBBmini is an autopilot / flightcontroller Cape for the BeagleBone Green. BBBmini + BeagleBone Green can be used as a state of the art Linux autopilot / flightcontroller for Copter, Planes or Rovers. BBBmini can be used with ArduPilot(open source unmanned aerial vehicle flight stack. BBBmini is a DIY project using widely available IMU and barometer breakout sensor boards, there is no SMD soldering necessary. The design is made that everybody can build a BBBmini by himself. In flight internet connection is done via WiFi link.

What does BBBmini offer:

DIY state of the art UAV autopilot / flightcontroller
Easy to build, no SMD soldering necessary
Free hardware, free software
Autopilot / flightcontroller software is running on Real-Time Linux
DIY friendly connectors 0.1” pin header
12 x PWM out with individual frequency for each channel
RC in connector for PPM, S.BUS or spektrum satellite input
MPU-9250 IMU 9 x DOF
MS5611 barometer
HC-SR04 ultrasonic rangefinder
GPS for full autonomous flights
Voltage and current sensing
I2C / GROVE connector for Status display and additional sensors
SPI connector for second redundant IMU
UART / GROVE connector for GPS
UART / GROVE connector for telemetry
CAN connector with on board CAN bus transceiver
USB connector used for WiFi, Laser rangefinder or cameras
Excellent cost-performance ratio

The BBBmini project development includes:

BBBmini documentation / how to
BBBmini PCB design done with Kicad all sources free available on Github
Device tree file for BBBmini hardware
PRU firmware: 12 x PWM OUT with better than 1us accuracy, separate frequency for each channel. RC input capture with 5ns accuracy, can be used to capture PPM, S.BUS or spektrum satellite
PRU firmware: HC-SR04 Ultrasonic Rangefinder device driver
Commits to ArduPilot project to get BBBmini supported by ArduPilot
Development of status display device driver for ArduPilot
Add redundancy sensors via SPI / I2C or UART
Lots of test flights and fine tuning in hardware and software to get a stable and reliable BeagleBone Green flightcontroller

See the BBBmini flying

Why BeagleBone Green

Once I had the idea to develop an flightcontroller, I have examined on the market available computer for their suitability. The following criteria should be met by the computer being used.

First, the computer should be very well supported by the community. As a result, a Raspberry Pi or BeagleBone could be used. In addition, the flightcontroller should be set up with as little as possible external components.

The decision was made for the BeagleBone. With the Programmable Real-Time Units of the BeagleBone, it is possible to create the BBBmini with only a few sensor breakout boards. In addition the BeagleBone offers many interfaces such as UART, SPI, I2C, CAN, USB and ADC. All these interfaces are used by the BBBmini.

BeagleBone Green parts used for BBBmini

Main CPU running Linux
PRU0 device driver for HC-SR04 ultrasonic rangefinder
PRU1 to generate 12 PWM signals and receive PPM, S.BUS or spektrum satellite input
Grove / I2C for communication to the status display, external compass or Laser rangefinder
GROVE / serial 2 for sensors like Laser Rangefinder
Serial 4 for telemetry radio
Serial 5 for GPS
ADC for voltage and current sensing
SPI1 for high speed data transfer from IMU and Baro sensor
SPI0 for high speed data transfer from second redundant IMU or other hardware
CAN for communication with ESCs and additional hardware
USB for WiFi and camera connection for life HD video transmission
Ethernet for communication on ground

Assemble BBBmini

Step 1: Solder resistor R4 and R5.

For 3.3V RC input signal use R4 = 0Ω (bridge) and R5 = open (see picture)

For 5V RC input signal use R4 = 1kΩ and R5 = 2kΩ

Step 2:

Solder resistor

R1 = 120Ω

R2 = 1kΩ

R3 = 2kΩ

R6 = 20kΩ 0.1%

R7 = 10kΩ 0.1%

R8 = 20kΩ 0.1%

R9 = 10kΩ 0.1%

to the bottom layer.

Step 3:

Solder CAN transceiver on the top layer

Step 4:

Solder male pin-header on top layer

P1, P2, P3, P4, P7, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21

Step 5:

Solder C1 and C2

Step 6:

Solder female pin-header P5 and P6 on top layer

Step 7:

Solder male pin-header P8 and P9 to bottom layer

Step 8:

Solder male pin-header to bottom layer of GY-9250 and GY-63

Step 9:

Mount spacer to BBBmini

Step 10:

Mount GY-9250 and GY-63

Finish! BBBmini is ready to use for Copter, Planes or Rover.

BBBmini + BBG

Prepare BeagleBone Green

Step 1:

Download Debian image to host computer

Step 2:

Decompress image

Step 3:

Copy image to microSDcard (>= 2GB)

/dev/sdX point to your microSD, be careful here!!! Use lsblk to figure out, which is your mircroSD. The process can take 15-30 minutes depending on the speed of your microSD card.

Step 4:

sync and remove microSD

Install Debian to your BeagleBone eMMC

Step 1:

Plug prepared microSD into BeagleBone

Step 2:

While holding down the boot button, apply power to the board. If there is a newer Debian installed, holding down the boot button is not necessary.

Step 3:

Wait some minutes until Debian is installed (all four LEDs turned on).

Step 4:

Remove power.

Step 5:

Apply power again.

Step 6:

Connect to the BeagleBone (password = temppwd)

Step 7:

Update Software

Step 8:

Install software

Step 9:

Update scripts

Step 10:

Install RT-Kernel

Step 11:

Add BBBMINI DTB

Step 12:

Adjusting the BeagleBone clock

Step 13:

Reboot system

Step 14:

Step 15:

Clone overlays

Step 16:

Change dir

Step 17:

Update DTC

Step 18:

Build and install overlays

Step 19:

Add ADC DTBO

Step 20:

Reboot system

Step 21:

Step 22:

Clone ArduPilot sourcecode

Step 23:

Change dir

Step 24:

Init submodule

Step 25:

Clone submodule

Step 26:

Change dir

Step 27:

Build Rangefinder firmware

Step 28:

Install Rangefinder firmware

Your BeagleBone is now ready to use.

Build ArduPilot software

BBBmini uses ArduPilot as flight stack. I contribute patches to the ArduPilot that BBBmini is supported by ArduPilotsoftware.

Compile ArduPilot native on BeagleBone

Step 1:

Step 2:

Step 3:

Step 4: (take about 1h20)

Step 5:

Cross compile ArduPilot (faster)

To compile ArduPilot for BeagleBone on an Ubuntu computer the following packages are required:

Get the source code and build ArduPilot:

Step 1:

Step 2:

Step 3:

Step 4:

Step 5:

Step 6:

Step 7:

Step 8:

BBBmini Test

For safety reasons dismount all propellers when testing BBBmini.

Step 1: Check connection to sensors

1. Connect BeagleBone Green via Ethernet to Network

2. Supply power to the BBBmini

3. Connect to BeagleBone Green from host computer with ssh

4. Start arducopter

Parameter description:

-B /dev/ttyO5 GPS connected to serial port 5

-C /dev/ttyO4 telemetry radio connected to serial port 4

5. Check if startup is successful

The output should look like this. HMC5843: Could not detect version does not matter, because there is not a HMC5843 connected. The non ASCII symbols are MAVLink messages, that is alright.

Step 2: Add arducopter to automatic start at boot time

1. Edit rc.local

2. Add automatic arducopter startup

Parameter description:

-B /dev/ttyO5 GPS connected to serial port 5

-C /dev/ttyO4 telemetry radio connected to serial port 4

Save and exit: Strg + o and Strg + x

Setup BBBmini Quadcopter

Step 1: Assemble frame

Step 2: Connect motors and ESC

Step 3: Connect power distribution

Connect each ESC to the power distribution board
Connect the 5V power distribution board output to BBBmini P11 power input
Connect the voltage and current sensing power distribution board output to BBBmini P21 voltage and current sensing pins

Step 4: Connect RC receiver

Step 5: Connect display

Connect your SSD1306 OLED display to P15 or I2C GROVE port

P15 or GROVE +3.3V to display VCC

P15 or GROVE GND to display GND

P15 or GROVE SDA to display SDA

P15 or GROVE SCL to display SCL

Step 6: Connect GPS

Connect your GPS to P10.

P10 +3.3V to GPS VCC

P10 GND to GPS GND

P10 RX to GPS TX

P10 TX to GPS RX

Step 7: Connect telemetry

Connect your telemetry radio to P7.

P7 +5V to telemetry radio VCC

P7 GND to telemetry radio GND

P7 RX to telemetry radio TX

P7 TX to telemetry radio RX

Step 8: Connect HC-SR04

Connect your HC-SR04 ultrasonic rangefinder

P19 +5V to HC-SR04 VCC

P19 GND to HC-SR04 GND

P19 TRIG to HC-SR04 TRIG

P19 ECHO to ECHO TRIG

Check / configure BBBmini

Plug USB telemetry radio into your host PC. I recommend to use APM Plannerground control station for beginners. Advanced user can use MAVProxy ground control station.

Step 1:

Start APM Planner

Step 2:

Change serial port to USB telemetry radio serial port

Set baudrate to 57600

Press connect button, wait for connection established

Wait some seconds to load parameters from BBBmini

Step 3:

Move BBBmini and check that Primary Flight Display is moving too

Step 4:

Switch to INITIAL SETUP

Step 5:

Switch to COMPASS

Hit button Live Calibration

Move BBBmini in all axis until calibration is completed

Step 6:

Switch to Accel Calibration

Hit button Calibrate and follow instructions

Step 7:

Switch to Radio Calibration

Hit button Calibration and follow intructions

Step 8:

Switch to Flight Modes

Setup that you are able to switch between Stabilize,LoiterandRTL

First Flight / Drive

Be sure all test are successful. Read and follow the safety instructions.

Because I did a lot of contributions to the ArduPilot project, BBBmini is full supported by ArduPilot software. Check ArduPilot website for instruction how to setup and use an ArduPilot autopilot. The ArduPilot website will provide you with all necessary information about how to build and fly (drive) vehicles with your BBBmini.

Links:

Quadcopter, Hexacopter, ...

Planes, VTOL

Rover (Boats)

Support

If you have questions about you BBBmini you can join the BBBmini user group on diydrones.com or ask for support at the gitter BBBmini support chat.

Links:

BBBmini user group

BBBmini support chat

Dual IMU (optional)

You can connect a second GY-9250 IMU to the BBBmini.

Setup 5GHz WiFi (optional)

Using USB WiFi with Linux can be complicated because of missing support of the WiFi chip by the Linux Kernel. It is very important to select a well supported WiFi USB stick. One of these are Ralink RT5572 based WiFi USB sticks. They can transmit at 2,4GHz or 5GHz. It is not necessary to compile a driver, it is supported by the Linux Kernel out of the box. With the Debian we use for the BBBmini you only have to install the firmware and some tools for the RT5572 chip with:

Here is a list with RT5572 based WiFi USB sticks.

You have to configure your location because the restrictions of the frequency usage depends of the country where you use the WiFi stick. For me it is DE for Germany. Replace DE to your country code.

Edit your WiFi configuration:

Save and exit with Strg + O and Strg + X

You can use WiFi to control your BeagleBone Green Linux, telemetry link or / and Live video transmission.