bealgebone black 工程

https://press3.mcs.anl.gov/forest/hardware/beaglebone-black-software/examples-and-tutorials/

Libraries

Examples and Tutorials

This is a collection of examples and tutorial code to learn how to use features on the BeagleBone Black.  The code has been tested on Angstrom 3.8 and Ubuntu 12.04 LTS.  It is released as is under the GPL license.  I have also put together how to login to your BBB and some useful commands to transfer code to and from your BeagleBone.  We will start with this because you will need to do this for all of the examples.  I will be primarily working in Linux (Ubuntu 12.04 to be specific), but I will try to also post Windows equivalents as often as possible.  Sorry MAC users no dice.

Quick Notation Notes

1. Code: Commands that look like this ssh [email protected] are Linux command line commands and are meant to be typed exactly as shown

Methods to Login to your BBB
Keep in mind these are only a few methods for those who don’t know how to start.  There are an almost endless number of other ways to do this.  Also if you are using Angstrom or another OS that supports a GUI then you can connect a monitor, mouse, and keyboard and skip this.

• USB – This uses the USB mini connection on the board to connect.
  • Linux
    • Plug the USB cable into your computer.
    • Wait for the board to initialize.  The leds should have gone all solid and be blinking.
    • Open terminal window.
    • type ssh [email protected]
    • It will prompt for a password but there isn’t one by default so just press enter
    • You should now be logged into the board home directory.
  • Windows 7
    • Plug the USB cable into your computer.
    • Wait for the board to initialize.  If this is the first time wait for the driver to load.  The leds should have gone all solid and be blinking.  Windows will also prompt a successful driver message the first time.
    • Use your favorite ssh client.  If you don’t have one I suggest Putty or Tera Term.
    • Now configure it to ssh to 192.168.7.2 on port 22
    • It will then prompt for password but there isn’t one by default so just press enter.
    • You should  now be logged into the home directory.
• Ethernet – This method assumes you are connected to the internet and using +5V barrel connector
  • Linux
    • Install Avahi with the command sudo apt-get install avahi-daemon
    • Connect the board and wait a few seconds for it to boot.
    • Run Avahi Zeroconf Browser.
    • Find the SSH Connection for Beaglebone and click.
    • This will give you the IP address of the board so simply SSH into the board like you normally would.
  • Windows
  • Router
    • If you have a router connecting your devices simply login to the router and get the IP.
    • SSH to the board and you are off and running again.

File Transfer Commands
As with the login methods this is one of many ways.  Feel free to comment with other ways you have used for the good of everyone.

• SCP from the BBB to your Computer
  • Send a single file
    • Open terminal window
    • Generically the command looks like this                                                                         scp user@IPAddress:/directory/filename.file /directory/
    • The first part after scp is the login information and file location on the BBB, the second part is where on the computer you want to copy it too
    • Example: scp [email protected]:/home/root/test.txt /home/
  • Send a directory
    • You can also recursively send an entire directory to sync folders
    • scp -rp user@IPAddress:/directory/ /home/directory
    • Same concept as before but now we specify the directory we want to recursively copy
    • Example: scp [email protected]:/home/root/Code/ /home/gavin/Code
• SCP from your Computer to Beaglebone
  • Same concept but in reverse
  • send a file: scp /home/filename.file user@IPAddress:/directory
  • send a directory: scp -rp /directory/ user@IPAddress:/directory
  • Example:                                                                                                                               scp /home/gavin/test.txt [email protected]:/home/root/Desktop/
  • Example:                                                                                                                               scp -rp /home/gavin/Code/ [email protected]:/home/root/Code/

Example 0 – Blinking A User LED
This example is your “Hello World” for the BBB.  This will show how to use file operations to change the state of one of the onboard user leds.  It also uses the time.h header to develop a function that pauses for a specified number of seconds.  A function to pause less than a second will be shown later.

Instructions
1a. Download Example 0 code (you have your choice of .tar or .zip) here and SCP the code or another method to get it on your board.
1b. Use svn: svn checkout https://repos.anl-external.org/repos/redac/BeagleBoneBlack/Examples/
2. Open a terminal window
3. Extract the code and navigate to the folder location: tar -xvf filename.tar filename
4. type make
5. type ./blinkusr to run the program

Example 1 – Blinking A GPIO Pin
This expands on the previous example by now blinking and led that is connected to one of the GPIO pins.  For this example, wiring an led with a 1K resistor to GPIO1_13 which is P8_11 on the headers.  Remember if you want to use a larger resistor to keep I/O drive current under 4 or 6 mA depending on the pin and 8 mA sink current a transistor can be added to switch the additional current.

Instructions
1a. Download Example 1 code (you have your choice of .tar or .zip) here and SCP the code or another method to get it on your board.
1b. Use svn: svn checkout https://repos.anl-external.org/repos/redac/BeagleBoneBlack/Examples/
2. Open a terminal window
3. Extract the code and navigate to the folder location: tar -xvf filename.tar filename
4. type make
5. type ./blinkled to run the program

Example 2 – Reading Button Input
The next logically step after learning to output a signal is to learn how to read an input signal.  This example will show you how to read the state of a button.  The internal pullup/pulldown resistors are not used here so you will need to wire in your button into GPIO1_15 or P8_15 with that in mind.

Instructions