75 lines
2.9 KiB
Markdown
75 lines
2.9 KiB
Markdown
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Beaglebone Black {#beaglebone}
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================
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The Beaglebone Black is a very maker friendly Board with a huge amount of
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available I/O Pins. It consists of an Cortex-A8 single core CPU plus two
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additional microcontroller cores called 'pru' that can be used for realtime
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tasks.
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The official Beaglebone Black Image runs Debian on a 3.8.13 Kernel. But there
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are also mainline kernels available, either from Robert C. Nelson or also as
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part of the upcoming Fedora 22 release.
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The kernel releases from Robert C. Nelson have usually more complete support as
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not all code is yet commited to mainline kernel, your mileage may vary!
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In Kernel 3.8.13 there is a Capemanager included, a mechanism to load
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configuration data for devices and extension boards from userland.
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This mechanism does not (yet) exist in Mainline kernels, so for mainline
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kernels you need to either rely on the pre-delivered devicetree's or you will
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need to build your own devicetree to support hardware not available by default.
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Revision Support
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----------------
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Beaglebone Black Rev. B
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Beaglebone Black Rev. C
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Interface notes
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---------------
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**SPI** works fine with 3.8.13 kernels, on Mainline Kernel SPI does currently
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not work. mraa will activate spi on 3.8.13 if it finds out that spi is not yet
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configured
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**I2C** works both on 3.8.13 and mainline. i2c is activated if missing for
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3.8.13 kernels
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Mainline Kernel requires the use of Device-Trees, mraa tries it's best to guess
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which gpio/serial/i2c/spi is connected where but there is currently no support
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to manipulate the Device-Tree settings from within mraa. If a device does not
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work as expected then please check syslog, mraa usually complains with a
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meaningful message when it is unable to initialize the device.
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It will also tell you which overlay for SPI/COM/I2C/PWM it tries to load, on
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some older Debian distributions (or heaven forbid, on Angström) you may need to
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install thoses overlays to /lib/firmware
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Capes and further documentation
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-------------------------------
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Correctly configuring i2c/spi/serial can get a little challenging as some pins
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have double functionality or are not available at all because hdmi is enabled.
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When something does not work as expected make sure to first check the syslog,
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then check the Beaglebone documentation. Some pointers for good descriptions
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are:
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http://elinux.org/BeagleBone_Black_Enable_SPIDEV
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http://elinux.org/Interfacing_with_I2C_Devices
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When working with mainline kernels take every hit you have on google with a
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grain of salt, a lot of documentation is based on 3.8 and older kernels. Using
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mainline kernels can be very rewarding, but at least at time of writing also
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can have some nasty
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pitfalls.
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Pin Mapping
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-----------
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mraa will take into account if you have hdmi cape or mmc enabled and will show
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you the gpio's available for your given configuration.
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To see the pin mapping use the command:
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$ sudo mraa-gpio list
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