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Thread: Drive bay touchscreen

  1. #1
    Anodized. Again. Konrad's Avatar
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    Default Drive bay touchscreen

    I'm planning to build an ARM-based integrated hardware monitor, fan controller, light controller, etc. Basically a semi-permanent PC chassis feature, ideally with a glitzy "big" touchscreen covering all or most of a drive bay facing. Maybe some knobs and buttons, too, if there's enough space.

    (I've discovered a few pre-made items of this sort, like the Aquaeros product line. Vastly overpriced. Really, really, vastly overpriced - especially since they break capabilities into modules and accessories which must be individually purchased. Too generic and simplified and powerless for what I want it to do, designed as a big-branded plug-n-play drop-in unit for wimps afraid to solder and code their own gear. Also, I want to put my hardware monitor where it belongs - meshed directly into the hardware - for it to have completely standalone and accurate and instant data, for it to not depend on the sloppy second-hand hearsay and latency of limited UEFI/BIOS and OS and USB-enumeration services. Kinda nice to see all your temps and how all your processor cores are loading before you even boot up an OS.)

    Standard 5.25" drive bays are 5.25" (141mm) wide and 3.5" (83mm) high. I'd like a touchscreen no smaller than about 4" wide, no larger than about 6" wide. The PC chassis offers about 1" extra space on each side, plus several inches of height - I would just prefer a landscape-oriented screen which is visually roughly equivalent to the devices mounted in drive bays underneath - dimensions are not critical. A screen with at least VGA 640x480 sort of resolution. Nice, bright, capable of displaying the usual full rainbow of colours. Exact resolution, landscape/portrait orientation, aspect ratio, etc, are irrelevant since I'll just build whatever LCD interface controller I need to make it work.

    Touchscreen technology is also unimportant, provided it responds to finger contact and doesn't require any tool or stylus to operate.

    I was thinking cellphone or PDA screen, but it's very difficult to get dimensional specs beyond the standard "corner-to-corner" diagonal which is proudly marketed. Sadly, it's also kinda hard to buy a dead unit with an intact screen - it invariably dies before any other component, in practice even the best-protected of "large" smartphone screens seems to break before the battery flatlines.

    I suppose I could always order a part from somewhere in Shenzen, but it seems like it shouldn't be too hard to find a broken/failed/blacklisted device with a good screen locally on the cheap, if I'm persistent.

    So my question - since I already have a great little smartphone and really don't much care about the fancy bling bling built into all the latest/greatest new toys - can anyone recommend some mainstream devices out there which have touchscreens that fit my parameters?
    My mind says Technic, but my body says Duplo.

  2. #2
    Why must hard drives fail together? TheMainMan's Avatar
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    Default Re: Drive bay touchscreen

    If you have someone you know with a US address, the Nokia Lumia 520 can be had new for $29.99 USD with no contract on Amazon.com. At 4" diagonal, it's on the small end of the range but they do come with fairly nice screens for the price.
    TheMainMan

  3. #3
    Moderator TLHarrell's Avatar
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    Default Re: Drive bay touchscreen

    Cheap Android tablets can be had for ~$30-50 and would easily be capable of doing what you want with some additional hardware. Optionally, you could keep the tablet as a standalone unit and wirelessly poll the data.
    I have a hammer! I can put things together! I can knock things apart! I can alter my environment at will and make an incredible din all the while! -Calvin

  4. #4
    Anodized. Again. Konrad's Avatar
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    Default Re: Drive bay touchscreen

    Oh, there will be wires. Everywhere.

    4" diagonal is just too wee for what I tentatively call the Computer Chassis Control Panel (CCCP).
    Great idea on the tablets, though, thanx!

    [EDIT:
    I've found this Raspberry Pi kit which fits my parameters almost exactly perfectly! 7" (165x100mm) 800x480 InnoLux AT070TN92 LCD/TFT with multi-contact non-stylus touchscreen, HDMI/VGA/2AV VS-TY2662-V1 controller board, anti-glare & fingerprint-resistant surface coat, reasonable price (vs similar touchscreens, anyhow) with free (but slow) shipping to Canada. Integrated USB interfaces for whatever dark purpose I might conceive. A largish variety of glasstops and bezels commonly available for this particular display panel.
    That problem solved, sorry to waste your time.]

    But now I'm having a bit of a stumble on the most trivial issue:

    I plan to light up an array of RGB LEDs, fully configurable via a colour-wheel sort of applet. Easy enough, each LED bank just needs to be controlled/powered by 3 or 4 PWM outputs, already plenty of PWM-capable IO pins available and more can always be ganged as needed through add-on PWM parts. But I am thwarted by the momentary-contact POWER (and RESET) switches - their LEDs need to instantly illuminate when switched, but PWM controllers invariably have a little bit of bootup delay. By "instantly" I mean with an imperceptible delay of, say, <10ms (arbitrary number). You press button, you see pretty colour-configurable light in button go on. So I think I need to wire their LEDs through a very fast-startup mcu part (like a TI MPS430?) and/or a very fast little bit of NVRAM (lol, to "instantly" cough up just a teeny tiny handful of 32-byte values, sadly). Is there a better approach without logic parts? Anyone done this before?
    My mind says Technic, but my body says Duplo.

  5. #5
    Moderator TLHarrell's Avatar
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    Default Re: Drive bay touchscreen

    Not sure about programming on the Pi, but can you set a default value for them to come on at before the rest of the UI is loaded up? I'm just learning this stuff myself with Arduino and some WS2812's.
    I have a hammer! I can put things together! I can knock things apart! I can alter my environment at will and make an incredible din all the while! -Calvin

  6. #6
    Anodized. Again. Konrad's Avatar
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    Default Re: Drive bay touchscreen

    I've never worked with a Pi board, don't know the answer to that (yet).

    I have worked with Cortex ARMs, I know of no such instant-boot option. Their bootloader takes a few milliseconds, their OS can take up to a few seconds more (depending on what hardware is present, what sorts of OS things start up). You can gain the appearance of an instant boot, just like with any smartphone or tablet, by leaving the thing running on standby. That requires a constant power source. A battery isn't impossible, but seems kinda involved for such a trivial feature. Perhaps I can leech a little +5VSB off the PSU, though I really don't know my ATX/APCI stuff, I don't know if the PSU will provide lots of +5VSB (rated for up to 4A/20W, although sleeping computer normally uses far less) or if it will deliver only exactly what the mobo BIOS reports is needed.
    My mind says Technic, but my body says Duplo.

  7. #7
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: Drive bay touchscreen

    *dusts off keyboard*

    Ok, let's see if I still remember how to do this 'forum' thing.

    A-series ARM SBCs (Single Board Computers) like the Raspberry Pi are a very different (and IMO much more user-friendly) beast than uCs (micro Controllers) like the Arduino/ARM-M3/etc. Think of it less like a logic controller and more like another computer (albeit a very small, low-power, one). Most ARM SBCs are designed to run either Linux or Android. Noting, that, let's take a step back here and look at what exactly it is you're wanting to do.

    Front end:
    - 4-6" touch screen
    - Video control/etc
    - Status LEDs
    - Physical button inputs

    Back end:
    - Interface with buttons for user input
    - Touch screen input for user input
    - Video screen for output
    - LEDs for output
    - Manipulate motherboard power controls
    - Read temperature sensors
    - Read other sensors maybe?

    Fundamental features:
    - Completely independent of host computer
    - Controls host computer
    - Instant (or near-instant) response to user controls

    What this all boils down to is a ton of GPIO (General Purpose Input/Output) pins and a battery for the SBC.

    What I would recommend is an always-on SBC controlling the host machine, that pulls power from the host PSU only when needed. Alternately, if you expect the host machine to remain off for long periods of time (say, several hours), then it might be a good idea to include a distinct power source for the SBC. Keeping the SBC online 24/7 would allow you to have instant response time for any actions, while keeping the whole system fairly simple and low-cost.

    If you haven't purchased a Pi yet (or if you have and are flexible) I would highly recommend checking out the Olimex OLinuXino boards. Specifically, the A20-MICRO, A20-LIME, or A20-LIME2 would be very well suited for your purposes. Personally, I would recommend the MICRO because even though it is twice the size, its GPIO pins are a much more workable 0.1" step pins (same as on the Pi and most breadboards) versus the 0.05" step pins on the LIME variants.

    I would recommend these boards for two reasons:
    1) They have a metric **** ton (technical term) of GPIO pins (160)
    2) They have built in battery power circuitry. All you would need to do is get a compatible battery (they even sell some) and hook the board up to an appropriate voltage source (MICRO takes 6-16V, LIME takes 5V).

    They also are way more powerful CPU/RAM than the Pi, which is handy.

    I have purchased from them before, and shipping to the US they're almost as fast as Amazon (seriously; it was something like 4 days from placing the order to it showing up on my doorstep, with standard shipping).


    [EDIT]
    Forgot to mention; Olimex also has screens, if you're not locked into the one from SAIN SMART yet.
    https://www.olimex.com/Products/OLinuXino/LCD/
    [/EDIT]
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
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    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  8. #8
    Will YOU be ready when the zombies rise? x88x's Avatar
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    Default Re: Drive bay touchscreen

    Ooooh, I just had an awesome idea. Make the UI a web interface, accessible on the in-host screen via a browser in full screen, hook the SBC up to your network, and you can get all the info/control from any browser.
    That we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours, and this we should do freely and generously.
    --Benjamin Franklin
    TBCS 5TB Club :: coilgun :: bench PSU :: mightyMite :: Zeus :: E15 Magna EV

  9. #9
    Anodized. Again. Konrad's Avatar
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    Default Re: Drive bay touchscreen

    I see that the LCD-OLinuXino-7TS also uses a AT070TN9X TFT LCD part, at roughly the same cost. The only dealbreaker on it is the resistive touchscreen, which likely requires a stylus. These screen kits may or may not be interchangeable, I guess I'll have to check specs for both of their interface/logic boards.

    I never knew about Olimex, I like it, I like it a lot. Open source, documentation, support, wiki, community, all looks very promising. Most of my local rPi resources are crazy greybearded ham radio groups - cool stuff, but not the droids I'm looking for. Methinks that - if my fussy touchscreen issue can be resolved - I shall migrate over to A20 products. Mucho overkill, little project seems to be growing up fast, but more robust capabilities are always better, more GPIO (without more complexity) is damn good.

    Maybe, yeah, basic LAN (and/or WIFI?) web interface. Perhaps some audio op-amps and on-screen digital equalizer, maybe. Password/security and "Reward if found" bootscreens. Options are limitless. But lemme focus on the essentials first (hardware/system monitor, fan/temp/pump control, light control, etc). The only problem (perhaps not a problem) I foresee with the largest Olimex board is PCB dimensions 142.24x82.55mm, just a teeny teeny bit larger than the drive bay plate mounted in front.

    I still have a pair of Model B+ Rasperries. Pathetically slow and feeble little things. Edging a little closer to craigslist every day, lol.
    My mind says Technic, but my body says Duplo.

  10. #10
    Anodized. Again. Konrad's Avatar
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    Default Re: Drive bay touchscreen

    [Off-topic in my own post ... already modded my ZM1250 Platinum PSU with some extra internal sensors, PWR_OK signals (and LED) to feed into my "CCCP", some minor thermal upgrades, a few kJs of MOV (with more LEDS!), etc. I plan to mate chassis+PSU+"CCCP" for many years of heavy use.]

    [Off my own off-topic ... got any favourite op-amp parts or circuits to recommend? Shouldn't be too hard to shield and isolate from the rest of the beast, unless I'm using Big Watt tubes or something, lol. Standard 3.5mm audio output, primarily for a budget-audiophile-collection of 32-40 Ohm headphones.]

    [Damn! I can also install a few-port LAN hub into a drivebay! And a power outlet bar along the bottom. I even have a nice little out-of-the-way place to velcro a Dollar Store flashlight for all those trips inside the PC, yeah that's how I roll.]
    My mind says Technic, but my body says Duplo.

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