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Multifunction instrument based on BeagleBone Black

shabaz

Hi Brian,

 

We're thinking on the same track. I'm interested to hear what your cape is like, and ideas you're considering for it's use and how good the touchscreen is. It looks like a very high quality screen. I've been experimenting with connecting up a larger LCD with the same resolution too, it may be the same model maybe, although I just have the bare LCD, not a cape, so I have a bit of interworking to do currently. I was undecided if I wanted to hook into the dedicated LCD pins (full color) like your cape, or go the PRU route (with reduced 256 or 65k color initially), since both methods could be useful depending on the application. I'd be interested to know if it works with the current release software, and what gets configured in Linux to set the correct timings (I've not really experimented with display drivers in Linux before, so I'm not sure where to look). I think it will be really neat if we can get several different sizes of LCDs working using both methods to cover a few different scenarios.

LCDs are so expensive though.

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  • Sources of inspiration.

    Whilst researching what is available I recently came across this from Digilent - Analog Discovery, Priced at $99 for US Students, $159 Academic and $199 for the rest of us (£136.09 Farnell UK) A real problem for me though is it's not open source and is tied to a windows PC. I think this type of product, designed for the education market, should be open source but that's another story. I have recently spent a lot of money on BBB bits and pieces so whilst I would love to play with one and see if I could interface to it a BBB and produce a linux / BBB equivalent to their software, I can't justify the expenditure at the moment. It would still be great if I could get one at the student price, better still if Digilent gave me one along with the design info image  Then again it would be great if I won the lottery. Well enough of the dreams back to the black...

     

    I got to thinking about designing something with similar functions but not tied to windows or PC.  I looked at the R-Pi which has great graphics capability but little I/O and I have had a number of issues using the USB at high speeds.   Then along came BBB and it was like the proverbial light bulb switching on. All the I/O pins and two PRUs and more than adequate graphics and and and....

     

    As Morgaine mentions above the OBLS and other "open source" products offer a solution and provide already working designs. I believe this to be a logical first step.

     

    Thoughts then are to use this wealth of usefulness and cherry pick the best bits to a fully integrated product onto a cape or two.

     

    Ok a tiny little bit of top-down design:

     

    1. Low cost portable multifunctional instrument capable of but not limited to being a Logic analyser, Oscilloscope, waveform generator, frequency spectrum analyser ...  A design that has both digital and analogue functions.

    1.1 Overall system control User interface and display
    1.1.1 Beaglebone Black with either LCD + Touch screen or (not so portable) HDMI monitor, keyboard and mouse.

     

    1.2 Digital functions
    1.2.1 FPGA Cape with I/O buffering and protection linked to BBB PRUs for real time control and data transfer

     

    1.3 Analogue functions
    1.3.1 ADC + DAC Cape linked to FPGA cape for high speed capture and to PRUs for real time control

     

    At this moment in time I am still getting to grips the the BBB and it's evolving 3.8 kernel and the various O/Ss that are available. Angstrom is ok, Ubuntu and Debian are fine but I quite like Arch Linux.  Of course the software for the "instrument" must not be dependant on any particular one though.

     

    It's getting late so I will leave it  there for now.

    Brian

  • in reply to bwelsby

    Brian Welsby wrote:

     

    1.1 Overall system control User interface and display
    1.1.1 Beaglebone Black with either LCD + Touch screen or (not so portable) HDMI monitor, keyboard and mouse.

     

    Worthy of note is that while the Pi's 1920x1200 resolution gives it a clear edge for media centre use, the BBB's 1280x1024 max is more than ample for an instrument display.  Indeed it would probably be overkill for most instruments.  On the display side, even without considering the BBB's mass of GPIOs and the PRUs which put it into another league entirely, this board seems very well matched to requirements.

     

    1.3 Analogue functions
    1.3.1 ADC + DAC Cape linked to FPGA cape for high speed capture and to PRUs for real time control

     

    At this moment in time I am still getting to grips the the BBB and it's evolving 3.8 kernel and the various O/Ss that are available. Angstrom is ok, Ubuntu and Debian are fine but I quite like Arch Linux.  Of course the software for the "instrument" must not be dependant on any particular one though.

     

    I've mostly shied away from the analogue side of EE throughout my career, so application notes and reference designs are my friend. image  I expect that the big players in analogue all have highly integrated devices for instrumentation front ends these days, with application notes to match.  With a bit of luck, creating reasonable instrument circuitry might be mostly a matter of component integration and careful layout+shielding, rather than original analogue design.

     

    Regarding operating systems, I agree with you there.  Whatever our personal preferences, the distros with the largest communities and the best support are likely to provide the quickest path to actually using an instrument, rather than spending days messing with the operating system.  Debian and Ubuntu have a clear lead there, followed by derivatives of these that use compatible ARM binaries and the same package management..

     

    Morgaine.

  • in reply to morgaine

    Morgaine Dinova wrote:

     

    Worthy of note is that while the Pi's 1920x1200 resolution gives it a clear edge for media centre use, the BBB's 1280x1024 max

     

    It turns out that the BBB isn't exactly limited to 1280x1024 as such. The limitation is down to the 125MHz pixel clock, or 85MHz if you want audio.

    This is a limitation of the am3359 it seems. The hdmi framer is capable of much more.

     

    Still, it seems that you can do 1920x1080x30 with audio, and the full 1920x1080x60 without audio - at least in theory. There's more work on the driver needed to enable it though.

     

    https://groups.google.com/forum/?fromgroups#!topic/beagleboard/4vge3Zs8dYE

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  • in reply to Former Member

    I did get 1920x1080p/24 on my Sony TV with one of the latest kernel builds so yes work is in progress.

    Looking at the framer data sheet (sorry can't remember where I found it now) it may also be possible to support 3D @ 1920x720 side by side but that is definitely for future experimentation once the kernel is stable.

  • in reply to bwelsby

    Brian Welsby wrote:

     

    Looking at the framer data sheet (sorry can't remember where I found it now)

    Interesting, I never could find one. NXP's website only seemed to have some marketing blurb saying it dould do various things with no real details.

  • in reply to Former Member

    Here it is  http://hipstercircuits.com/ scroll down to "MAY 8" and the links are there.

  • in reply to Former Member

    selsinork wrote:

     

    Still, it seems that you can do 1920x1080x30 with audio, and the full 1920x1080x60 without audio - at least in theory. There's more work on the driver needed to enable it though.

     

    https://groups.google.com/forum/?fromgroups#!topic/beagleboard/4vge3Zs8dYE

     

    Awesome!  More crispness in display is never bad, even if it's just to make the instrument have nicer text.

     

    Audio can always be handled in some other way instead of being multiplexed onto HDMI, for example by tapping into the I2S header signals, or using a separate audio device on USB, or using network audio.

     

    For use outside of instruments, some will bemoan the lack of video decoding in comparison with Pi, but given our focus on engineering applications and not media consumerism, that "lack" may well be an asset.

  • in reply to bwelsby

    Brian Welsby wrote:

     

    Here it is  http://hipstercircuits.com/ scroll down to "MAY 8" and the links are there.

     

    HipsterCircuit's "A working display" in the June 1 post shows the monitor's EDID as having the same max resolution as the BBB has as shipped, so it's probably an edge case, ie. an exact match of capabilities.  Just for reference, my BBB is running into a Dell 2408 and shows, as one might expect:

     

    root@bbb:/#  parse-edid /sys/class/drm/card0/card0-HDMI-A-1/edid

    parse-edid: parse-edid version 2.0.0

    parse-edid: EDID checksum passed.

     

            # EDID version 1 revision 3

    Section "Monitor"

            # Block type: 2:0 3:ff

            # Block type: 2:0 3:fc

            Identifier "DELL 2408WFP"

            VendorName "DEL"

            ModelName "DELL 2408WFP"

            # Block type: 2:0 3:ff

            # Block type: 2:0 3:fc

            # Block type: 2:0 3:fd

            HorizSync 30-83

            VertRefresh 56-76

            # Max dot clock (video bandwidth) 170 MHz

            # DPMS capabilities: Active off:yes  Suspend:yes  Standby:yes

     

            Mode    "1920x1200"     # vfreq 59.950Hz, hfreq 74.038kHz

                    DotClock        154.000000

                    HTimings        1920 1968 2000 2080

                    VTimings        1200 1203 1209 1235

                    Flags   "-HSync" "+VSync"

            EndMode

            # Block type: 2:0 3:ff

            # Block type: 2:0 3:fc

            # Block type: 2:0 3:fd

    EndSection

     

    This is an example of the more generic case then, with the BBB noting that the monitor is capable of more but correctly limiting its output to the best that it can do that is still compatible, or in my case 1280x1024@60Hz.  All working as expected.

     

    PS. For fuller test coverage of EDID handling, one would also need to check operation into a display of lower resolution than the BBB's max --- quite likely to be relevant to instruments.

     

    Morgaine.