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Beagle Bone Black: $45 -- Raspberry Pi/Arduino alternative

Discussion in 'Home Power and Microgeneration' started by j, Apr 24, 2013.

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  1. j

    j Guest

    This caught my attention:

    http://www.extremetech.com/extreme/...i-and-arduino-on-a-single-board-for-just-45/2

    Roughly, it is a faster version of a Raspberry Pi with an Arduino like
    GPIO. And for $10 more than a Raspberry Pi.

    I got my Raspberry Pi a week ago and I was blown away by the
    possibilities of just that. And previously amazed at the Arduino.
    Sensors and servos are so readily available and cheap that all kinds of
    control projects are doable. There is already a huge amount of open
    source code ready for the download. It's evolutionary and revolutionary
    for small players like myself (and some of you guys!).

    Jeff
     
  2. Neon John

    Neon John Guest

    They're gouging. TI has the Black on their site for $35, the official
    list price.

    I'm designing our company's next generation induction heater around a
    BB White so I'm intimately familiar with the product. It is being
    sold as a general purpose system-on-a-board (SOB) but it is not. The
    embedded Linux is barely complete enough to run the Ethernet and
    generate a login prompt. For anything else plan on being a kernel
    hacker. I've had to hire a programmer to write a custom SPI port
    driver because the included one (which only uses 1 of the chip's 3
    ports) is barely functional.

    To get audio and video from either the White or Black, one has to buy
    "Capes" (expansion boards). The driver support is fairly poor from
    what I'm reading on the support list.

    I've avoided the Pi because it isn't open source and because of the
    hype but I think that if you wan an SOB that you can just turn on and
    use, the Pi is probably the answer.

    John
    John DeArmond
    http://www.neon-john.com
    http://www.fluxeon.com
    Tellico Plains, Occupied TN
    See website for email address
     
  3. j

    j Guest

    I couldn't find it there. I saw the old model for $89.
    This claims it has a micro HDMI out (no separate audio):

    http://www.bit-tech.net/news/hardware/2013/04/24/beaglebone-black/1
    There's a ton of stuff for it (Pi) on Github, including openCV (which
    should run on BB) and openBR, which suits my fancy. Also a choice of
    OS's. Raspbian Wheezy is functional and runs Libre Office, as well as
    the Chromium browser, albeit slowly for a complex site. The USB is
    crippled though and loses bandwidth dropping packets.

    What caught my attention on the BB was that it could stream HD. I was
    clueless on the driver/software support but didn't imagine that it was
    that bad.

    My uses for it are a mix of art and AI. I've made some remote control
    mobiles with the Arduino and have some solar thermal control stuff to do
    with that as well. This all still excites me as the possibilities are
    endless, 40 years ago I was etching boards and using the first gen ICs,
    this is so much easier and more powerful.

    Thanks,
    Jeff
     
  4. j

    j Guest

    The scheduling is very cool. RaspPi isn't bad for GPIO:

    https://www.dropbox.com/s/m5l185qxq9w5mzk/raspberry-pi-gpio-cheat-sheet.jpg

    There is a lib that gives 8 PWM outs (shares a timer), I don't think you
    needed that though.

    On the other hand, logging and WiFi and having memory to burn (and
    Python as a high level wrapper) is very cool and easy.
     
  5. Neon John

    Neon John Guest

    Thanks Morris.

    What I needed is somewhat specialized. I'm sampling an analog signal
    at 1 megasample/sec using an Analog Devices SPI A/D converter. The
    SPI clock is the sample trigger so it has to be precisely on frequency
    and of low jitter. If not, the FFT that follows is all over the
    place.

    The SPI driver that comes with the board runs at a low priority and
    the preempting causes as much as half a clock cycle jitter. Totally
    unsatisfactory.

    I worked on the problem for a couple of weeks, time lost to the
    product design, when I reminded myself that I'm a EE and not a kernel
    hacker. I found a guy in England who is a kernel expert and did the
    driver in just a few hours. We took a very simple approach. The size
    buffer is programmed with an IOCTL call. The buffer is in kernel
    space. When the call to take a sample is made, everything else is
    preempted while the driver runs the port for the designated number of
    samples.

    There is still some clock jitter resulting from phase-locking a (I
    think)24 MHz crystal up to 700MHz and then back down to the 48 MHz SPI
    clock. But the FFT smear is tolerable for this application.

    The important point I wanted to make is that the BeagleBone is not
    souped up Arduino as it's being called. It's only for Linux experts
    (or those who want to be) and certainly not for someone inexperienced
    in Linux internals who is just trying to get a project done.

    I could write many more paragraphs but I'll stop here. The only
    reason I've stuck with it is that I need the raw speed and the
    built-in "neon" DSP instructions.

    John
    John DeArmond
    http://www.neon-john.com
    http://www.fluxeon.com
    Tellico Plains, Occupied TN
    See website for email address
     
  6. j

    j Guest

    So, I hesitated and then bought a BBB.

    It came loaded with Angstrom 3.8.6 and a few basics loaded on the eMMC.
    I needed to buy a power USB hub and a micro HDMI adapter. Otherwise
    getting to a desktop was painless. It boots into Gnome and has the
    basics installed.

    It runs much snappier than the Pi, (but I had the Pi on a class 8 SD).
    The performance monitor on the BBB rarely shows 100% CPU, and the Pi
    often did. It has a lot more chips on the board than the Pi, so things
    like the ethernet aren't shared with the USB. All the needed hardware is
    there.

    With that said, working on the Pi, installing software and updating the
    kernel is much easier on the Pi and Raspbian Wheezy. The Pi community
    and support is better thought out. And, the BBB is very new and there
    are some bugs and such.

    I suppose if I moved to a different distro like Ubuntu this would be
    better, but Angstrom seems a better match for tinkering.

    The GPIO is mind boggling. I haven't gone cape shopping yet. I'm looking
    for something simple.

    Jeff
     
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