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Error/Beep/Blink codes

Discussion in 'Embedded' started by D Yuniskis, May 2, 2011.

  1. D Yuniskis

    D Yuniskis Guest


    I have three layers of "degradation" in the event
    of various degrees of system failure:

    1) if just some *aspect* of the system fails (e.g.,
    an application crashes, etc.) then I provide high
    level error reporting with diagnostic assistance.
    E.g., a "window" can appear explaining the nature
    of the problem and suggested remedies, etc.
    [note that I only offer that by way of an example
    to which you might relate; that's *not* what I
    actually do...]

    2) if significant portions of the system are in
    an unreliable state, I present an unadorned error
    that, at least, *says* that there is an error and
    what it is (accompanied by a unique identifier
    that helps pinpoint where the error is raised).
    E.g., this is the equivalent of the "blue screen
    of death".

    3) if *most* of the system appears unreliable, I need
    to fall back to some sort of "if all else fails"
    mechanism that is *guaranteed* to be able to convey
    information (unless the processor is toast).

    This last level is roughly the equivalent of BIOS
    "beep codes" -- where the hardware and software required
    to drive the *display* can't be relied upon, etc.

    Obviously, beep/blink codes can't say much in a manner
    that the casual user will be able to comprehend. So,
    the goal is to pare down the information presented to
    a careful balance that addresses three classes of people:
    - the casual user who knows little more than "it's broke"
    - the motivated user who will look up an error code for
    more information
    - service personnel who can pinpoint the exact cause
    for the signaled error "code"

    [note that I also have a means of passing "diagnostic data"
    out to service personnel -- but, that requires them to have
    possession of the device]

    So, I want a scheme that addresses all of the above without
    requiring their intervention -- since that would require more
    of the system to be functional than an "output only"
    mechanism as well as requiring some confidence in their ability
    to correctly interact with a failed device (which is an
    exceptional condition so not the sort of thing they are likely
    to have "practice" doing!).

    Taking audible annunciators, first...

    You can vary only a few characteristics of an audio signal:
    - volume
    - frequency
    - duration/interval/rate
    - count

    [note that amplitude modulation and/or frequency modulation
    fall into these categories]

    You can't control "absolute" volume -- there are no controls
    in the device that you can count on as functioning (it's broke,
    remember??). So, in practical terms, you pick *a* volume
    level that you expect to be audible without alarmingly so
    (too loud is worse than too soft since a user realizing the
    device to be broken will pay closer attention to listen to
    "soft" sounds whereas a *loud* device report may be inappropriate
    for the current environment (e.g., a business meeting).

    And, a user can't probably resolve more than two relative volume
    levels. And, since they are *relative*, EVERY error code mapping
    would have to employ both levels for the user to judge between

    The same sorts of arguments apply to frequency and duration et al.

    All of these "relative" indicators require the user to remember
    past sounds in order to qualify them based on *future* sounds.
    I.e., "Was that LOUD LOUD LOUD or SOFT SOFT SOFT?" The answer
    isn't known until the user has been exposed to all variations.

    With that in mind, any error code format should ensure that
    these variations are in expected places. For example, beginning
    each error with a LOUD SOFT preamble lets the user *know* what
    loud and soft levels are *before* he has to "listen to the DATA".

    IMO, the format should be fixed so the user knows what to expect
    and when to expect it. E.g., preamble, value, postamble. So,
    this implies all error codes should be the same number of "digits".

    Further, the number of different *types* of digits should be
    small. So, perhaps three groups of 1 to 4 beeps. Or, a series
    of three different beeps (LONG, SHORT, SHORT vs. LONG, SHORT, LONG).

    Obviously, there are lots of ways of encoding data with these
    different attributes.

    I'm pretty convinced that varying amplitude (two levels) is
    The Wrong Way to go about encoding things.

    In my opinion, the classic "beep COUNT" approach, takes a fair
    bit of time to emit a complete "error code" (e.g., imagine three
    groups of 1-4 beeps at 1 second intervals with a 2 second pause
    between groups -- 64 possibilities taking as much as 15+ seconds
    to issue). This requires the user to "remember" what has come
    before while concentrating on what is happening *now* (i.e.,
    "There were 3 beeps, followed by 2 beeps and now this is the
    first beep in the third group of beeps...")

    I *think* a better approach may be to alternate between a set
    of frequencies. E.g., 64 codes can be expressed with a set
    of six tones -- ~8 seconds for the entire code to be emitted.
    I think even those folks who need a bucket to carry a tune
    could "remember" something like "dah dee dee dee dah dee".

    OTOH, it's not intuitive to map dah's and dee's to "symbols"
    so a non-techy would never think of translating this to
    the more memorable ABBBAB or 011101 or ...

    Argh... tired of typing. Hopefully, this is enough to get
    some initial comments on various approaches. Let's avoid
    the visual analog of all this for the time being -- unless
    your argument relates to a duality that is or is not present
    in different encoding schemes...

    D Yuniskis, May 2, 2011
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  2. D Yuniskis

    Rocky Guest

    What about morse code? Nokia did it on the old cellphones for SMS.
    dit-dit-dit dah-dah-dah dit-dit-dit
    Our microwave would give the sound of a heart monitor flatlining when
    it finished.
    blip --- blip --- blip --- beeeeeeep
    Rocky, May 2, 2011
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  3. D Yuniskis

    upsidedown Guest

    At least make sure the modulation goes nicely through various cellular
    codecs. For instance some kinds of amplitude might be defeated by the
    a.g.c. in the telephone signal chain.

    For repeatable errors (such as power up errors), it would be handy to
    tell the customer to put the cellular phone close to the device and
    repeat the error. The support person could then listen for the
    sequence him/herself and not rely on the end user interpretation of
    the error code.

    Do you really have that much error situations, in which a more
    expressive error method can't be used.

    If the problem is not repairable by the end user or local
    representative, is there much point in going into too much details in
    the error codes ?
    upsidedown, May 2, 2011
  4. The Morse code is a nice idea and those interested in what the error
    actually is should get used to reading the code easily enough provided it
    was, at most, kept at about 6 to 7 words per minute rate. Faster rates need
    more concentration on the part of the listener.

    Tiered error-state fall-backs are sensible depending on the remaining
    capability of the system to function. Less easy to arrange in single
    processor systems but in the latest multi-core devices there is no reason
    why one of the cores couldn't be programmed to monitor and give the last
    ditch provision of useful debug information. Having used several processors
    in a system (each programmed for their own specific tasks) it nearly always
    made sense to have a robust system status monitor processor to communicate
    what was going on in the rest of the system.

    Paul E. Bennett...............<email://>
    Forth based HIDECS Consultancy
    Mob: +44 (0)7811-639972
    Tel: +44 (0)1235-510979
    Going Forth Safely ..... EBA. www.electric-boat-association.org.uk..
    Paul E. Bennett, May 2, 2011
  5. D Yuniskis

    D Yuniskis Guest

    Wow! What an *obvious* idea -- and one that I would have *completely*
    overlooked! This makes even more sense than the other "more expressive"
    mechanisms that I use *before* things deteriorate to this point!!

    I.e., use something like the phone company uses for status messages
    -- preceding each spoken message with a series of tones that tell
    you what the message really contains (in abbreviated form). Much
    like prefacing a text message with a numeric code (that can be
    easily parsed by a piece of software).

    Hmmm... I will need to rethink this approach with this in mind!
    The problem is that the "remedy" beyond this point is very
    expensive -- factory service. This is 24 hour turnaround (!).
    Just the shipping costs alone (forget the labor to troubleshoot
    and repair) can eat you alive!

    So, you want to be able to get as much information from the
    device *without* having it in your possession.

    E.g., consider a laptop and a "casual user": "It doesn't work".
    - is the battery discharged?
    - is the battery incapable of holding a charge?
    - is the device *actually* running off AC power?
    - is the disk spinning up?
    - is something in the BIOS configuration hosed?
    - is the backlight dead?
    - has the disk image been corrupted?
    - is the CPU/GPU overheated (fan failure)?

    You *could* try to talk the user through this sort of diagnosis
    over-the-phone. *Maybe* he can hear a spinning disk. *Maybe*
    he can feel airflow from a cooling fan. Maybe he is telling the
    truth when he says the battery has been charging for 6 hours. etc.

    But, that effort costs you time/money. And, it will aggravate
    the user when he has invested EVEN MORE TIME "doing YOUR work
    for you" (over the phone) only to face the possibility of
    being told, "Gee, we don't know what the problem is... send the
    unit in to us..."

    All of these are worthwhile bits of information to have
    *before* resorting to "ship the 'defective' unit to us *while*
    we are 'overnighting' a replacement to you". Having a way to
    get information from the device itself without relying on
    the user's "interpretation" of symptoms, etc. is a big win.
    The device *may* be "fixable" (not necessarily "repairable")
    by the user. E.g., if you can verify that the problem is a faulty
    battery, then you can just ship a replacement battery to the
    user for far less cost and EFFORT (yours as well as the user's)
    than replacing the entire device.

    A "local representative" requires you to *have* folks in the
    field to support the devices. That imposes a big fixed cost
    "just in case" things *might* break. Easier if *you* can just
    give the user an answer and a remedy in short order.

    E.g., apparently, a *huge* percentage of "returned" disk drives
    test as "No Defect Found". So, the manufacturer absorbs a
    big cost for testing and replacing those devices needlessly.
    And, runs the risk that the "replacement" device may be regarded
    as "similarly defective" (i.e., the first error was apparently
    user related or a consequence of some other aspect of the
    application that used the drive -- "software bug"?) which
    reflects badly on the disk manufacturer. (people remember
    returning the drive and might not remember that the real
    problem was proven as "elsewhere")

    If, OTOH, the drive manufacturer could talk to the drive
    *without* having to rely on all the other bits of the
    "system" in which it was employed, then many of these
    problems could be avoided.
    D Yuniskis, May 2, 2011

  6. If you can do amplitude and frequency modulation, why not just speak
    the error codes? Of course that means you have to pick a language.
    robertwessel2, May 2, 2011

  7. Consider a freq. SWEEP.

    Perhaps a sweep UP - followed by beeps for the 'tens'.

    then a sweep DOWN -followed by the unit beeps (0 or 1-9)

    then pause or steady tone, then repeat.

    Not a dissimilar problem automakers had from the pre-OBDII system in
    cars that would have a light flash long/short/very-long, to yield
    troublecodes. (maybe check troublecodes.net or .org w'ever for
    1 Lucky Texan, May 2, 2011
  8. D Yuniskis

    upsidedown Guest

    When multi megapixel pocket cameras are common and cellular phone
    cameras reach at least VGA or even megapixel resolution, why not
    generate static error code displays and ask the customer to use a
    camera or cell phone to send a picture of that situation. We have been
    able to detect missing terminators and other wiring problems this way.

    I mostly work for a company with offices in quite a few countries all
    over the world, unfortunately most of the countries, in which English
    is not the native language (including the HQ).

    If you have time (at least a few days) to be familiar with the English
    dialect spoken by the other person in a different country, the
    communication starts to be productive.

    However, in problem solving situations, people usually meet for the
    first time and the problem has to be solved in an hour or so, so there
    is no time to learn the dialect of the other partner.

    For this reason, we try to encourage e-mail (and other written
    communication) to avoid the problems with dialects. Asking to take
    pictures is often more productive than trying to ask someone to do
    complex sequences, if we do not have a common language.
    upsidedown, May 2, 2011
  9. D Yuniskis

    Rob Gaddi Guest

    I don't remember who, but at one point a PC motherboard manufacturer
    was, in addition to putting the BIOS beeps, putting down a single
    7-segment LED. It was the easiest diagnostic tool I've ever used. Must
    have been some fairly high-end motherboard; I can't see most of them
    parting with those 29 cents lightly.

    If you've got room and pins, it's not a bad answer. Flash each digit
    for a second, then blank the display for two seconds. Define your
    status codes so as to not use any numbers with two consecutive digits
    the same.
    Rob Gaddi, May 2, 2011
  10. D Yuniskis

    Jon Kirwan Guest

    BIOS 'post' codes were actually displayed on the front panel
    of some machines I worked on, starting nearer the end of the
    80286 days and just before the 80386, memory serving. These
    responded to port 0x80 and 0x84, something like that? Two
    7-seg digits wide. (I don't recall single digit cases.) They
    could be installed on the motherboard, extended out to case
    exterior, or added into an ISA slot, 8 or 16 bit, if
    available, or simply "across" the south bridge in some
    fashion. I still have a baggy of these post cards I could
    add into any machine with an 8-bit ISA slot. (Yes, I still
    have a few operating machines I use with ISA slots, too.)

    I've got the same two-digit display on my newly purchased
    gigabyte motherboard, though there is no south bridge and no
    ISA capability. So I'm not sure how it is accessed from
    software, anymore. It seems strange to imagine a pci
    interface for it, so I'm guessing some of the chipsets
    include pins for the purpose or otherwise internally still
    catch those I/O addresses, after power-on configuration sets
    up the chipset.

    Jon Kirwan, May 3, 2011
  11. D Yuniskis

    D Yuniskis Guest

    Hi Robert,

    Wrong audience. :> I doubt "GrandMa" is going to know Code!
    And, any implementation like that would be too "rich" for the
    information content it carried (unless you restricted yourself
    to all symbols of, e.g., 3 tones -- in which case, being able
    to map those tone sequences to "letters" doesn't really buy you

    I think it is important that the format of the "error code" be
    rigidly constrained. If, like Morse, a symbol can have different
    numbers of elements (e.g., dit vs. dah-dah-dah), then you run the
    risk of a user failing to perceive/remember a portion of the
    code and effectively morphing one code into another. E.g.,
    there is a reason you say "code 001, code 142, etc." and not
    "code 1, code 142, etc."
    D Yuniskis, May 3, 2011
  12. D Yuniskis

    D Yuniskis Guest

    Hi Paul,

    Gack! I, for one, don't have the "auditory acuity" (?) for
    such tasks (one reason I never took the Ham exam when I was
    The same sorts of mechanisms can be applied in single processor
    devices *if* you plan for it from the start. Much harder to
    try to retrofit that capability into an existing system ex
    post factum -- unless you get lucky! :> It also is a lot
    easier if you design the hardware with this issue in mind.

    E.g., to return the to laptop analogy I mentioned elsewhere...

    If you can't control power to the disk drive, then a "low
    battery" will cause the entire system to "refuse to start"
    (because of the load placed on the battery by the disk
    trying to spin up dragging the power supply down *as* the
    processor is trying to report a failure, etc.)

    "Reliability" is a wee bit harder to fit into designs, eh? ;-)
    D Yuniskis, May 3, 2011

  13. It's still port 80h, with either word or byte writes to that port.
    That was one of the DMA ports on the PC/XT, but that changed with the
    AT. AFAIK, the PCI POST cards are handled as legacy devices and get
    the fixed assignement to port 80h. PCIe versions appear to exist.
    robertwessel2, May 3, 2011
  14. D Yuniskis

    Jon Kirwan Guest

    The problem I still have with accepting that is that there is
    no ISA bus, anymore, and not even a south bridge to emulate
    one. How are frontside bus I/O transactions moved through
    the chipset to such a display, these days, without the south
    bridge? I know it works. I can see it. I just know that it
    doesn't happen like it used to and am curious.

    CPU hits an I/O instruction. Start there. Which frontside
    bus transaction takes place? If the chipset picks it up, how
    does it handle it? (Used to be a south bridge and sideband
    channel wires between the north and south bridge to mediate.
    Now there is no south bridge, no sideband.) There certainly
    are no ISA bus transactions, anymore, so the old logic
    methods don't apply.

    Jon Kirwan, May 3, 2011

  15. Not quite sure I understand the question - it's just a PCI (or PCIe)
    transaction to an I/O mapped BAR on a particular device. Now as to
    the specifics of a PCI POST card, I don't know, but once it's
    configured, it should be no different than (say) a legacy serial port
    or basic VGA support. The configuration question is somewhat
    interesting, but I assume most POST cards just supply a default
    configuration (or perhaps even a fixed one). Most bridges should come
    up with I/O address filters turned off, so I/O transactions should
    bounce around everywhere as soon as the bridges are enabled.
    robertwessel2, May 3, 2011
  16. D Yuniskis

    Thad Smith Guest

    I have used a variable number of beeps: beeeeeep, (pause) beep, beep, beep. The
    number of short beeps is the code. I think I used about 2 beeps / sec.

    If you have many possible codes, then separate them into digits with a space in
    Thad Smith, May 5, 2011
  17. D Yuniskis

    D Yuniskis Guest

    Hi Robert,

    Speech (crude) takes about 40KB (or are you just suggesting
    something like canned saydigit(digit)?)
    D Yuniskis, May 5, 2011
  18. D Yuniskis

    D Yuniskis Guest

    Hi Rob,

    I've seen similar front panel displays. One even showed which
    disk block was being accessed (um, isn't this as useful as
    the myriad "status lights" on old mainframes? :> )
    I was hoping to find a solution that had an audio counterpart
    (i.e., "blink" in contexts where visual indicators make sense;
    "beep" where they don't)
    D Yuniskis, May 5, 2011
  19. D Yuniskis

    D Yuniskis Guest

    Fine -- *if* you have a visual "display" to photograph! :>
    The point of my beep/blink query was to try to come up with a
    scheme that could treat visual and audible "indicators"
    D Yuniskis, May 5, 2011
  20. D Yuniskis

    D Yuniskis Guest

    Hi Thad,

    Yes, that's what I've seen in many BIOS's.

    But, I am questioning the cognitive load that it imposes
    on the user. I.e., he has to count the number of beeps
    in the "current digit" while *remembering* the number
    of beeps in previous "digits".

    At what point does this become a source of error? Are
    there other "encoding methods" that are *less* error
    D Yuniskis, May 5, 2011
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