1. We've officially relaunched the store! Check it out by clicking "Store" at the top of the page!
    Dismiss Notice

Hared-brained PCB schemes, aka "it's not meant for that, idiot"

Discussion in 'General Discussion' started by ahrlad, Mar 2, 2019.

Tags:
  1. ahrlad .

    Joined:
    Oct 29, 2017
    Messages:
    29
    Likes Received:
    20
    From the department of "don't worry, I'm dumb enough to give it a go"; I've put JLCPCB hard at work

    [​IMG]
    This outline is for 7" 800*600 displays such as A070SN01 etc. I did alternative bottom tiles dimensioned for the 6.5", 800*480 AT065TN14

    [​IMG]

    All broken up into <10x10cm tiles to take advantage of their ridiculously cheap prices for small boards

    This is a pretty bad gross layout and stuff but you gotta place the order sooner or later. Will need bodge jumpers.

    [​IMG]

    Audio amp: TPA6011a4pwp class AB hp + speaker output, dc voltage volume control, analog input
    DC voltage regulation by TPS56528 5A bucks. 5v for teensy, amplifier and lcd board, the 1.25v and ldo regulator parts of the board is optional if doing the standard ps2 board mod

    Squishy tacts for dpad and buttons. Side actuated switches for triggers, I haven't figured out how to do them yet but hey, something will show up

    [​IMG]
    This board I'll cut in half and connect by header, to get the height difference between squishy tacts and analog stick. I've no idea how it'll work out, my brain's pretty bad at 3d

    [​IMG]

    Charging solution(?): tp5100 2s 1.5a charger module (sink mode). Plus: under- and overvoltage and -current protection board + 2s balancing thingy, HX-2S-JH10. Should give me a charge+play solution since the tp5100's charge only
    [​IMG]
    Made a huge order of m2 and m3 spacers and fasteners, both nylon and brass. My plan is to secure them to the board along the edges, then fashion a z axis with epoxy and tiles that fit into the slots at the edge of the boards. I've got tiles to fashion a bottom side of the thing as well

    [​IMG]


    PCB cost: $100 including shipping for enough stuff to make five each of at065tn14 and a070sn01 versions. TPA6011 and TPS56528 can be got from china at about $1 each, and the teensy can be had for around $9. The LCD's can be had for $15-$20 each, plus cost for controller board

    Will update when I get the stuff and/or any of it makes for fun reading
     
    Gman, BocuD, Stitches and 1 other person like this.
  2. ahrlad .

    Joined:
    Oct 29, 2017
    Messages:
    29
    Likes Received:
    20
    To leverage the Teensy and reduce number of buttons, we can use it to control the standard rtd2660 boards with 5 button inputs. The inputs are read by the pcb800099 by a 6-bit adc pin pulled up to 3.3v, while a resistor network connects to the different button inputs. To wit,

    RTD2660_pin53->[100ohms] ---||(connection to resistor network: --v--)||---->[4.7k]---3.3v

    [Function][resistor value]--->gnd;
    [Power]--->[0r0]-->gnd
    [Menu]--->[1k]--->gnd
    [+++]--->[2k]--->gnd
    [---]--->[3.9k]--->gnd
    [Source]--->[10k]--->gnd

    Giving us values at the ADC pin like this for each button:

    [Power]: 0
    [Menu]: 11
    [+++]: 19
    [---]: 29
    [Source]: 44

    By pulling down multiple resistors to ground, we should get a few more values to work with, for instance driving [source] + [---] low would give us 24 or thereabouts at the ADC pin, which the ADC should be able to discern from neighbor values. The teensy does 5v logic of course, but I figure I should be able to set the pins connected to the resistor network to high impedance input pins, so writing to the data direction register will respec the pins straight from high impedance to active low, and back again.

    "What's the point," you ask? Well, putting the teensy in charge of input to the LCD controller means I should be able to navigate the OSD with the dpad and buttons, by a toggle of some sort to switch between modes. If I can get it to communicate with the board reliably, I should also be able to make the OSD keep track of battery levels, backlight level and volume, either by coopting pins from the lcd controller board or doing it from the teensy.
     
  3. Warguy64 .

    Joined:
    Oct 10, 2018
    Messages:
    6
    Likes Received:
    2
    God damn, looks like it took a long time. Would love to see it working!
     
  4. cheese the tallest memer in town Staff Member . . .

    Joined:
    Mar 2, 2016
    Messages:
    2,337
    Likes Received:
    2,205
    Location:
    Florida
    Looks pretty neat, can't wait to see more
     
  5. ahrlad .

    Joined:
    Oct 29, 2017
    Messages:
    29
    Likes Received:
    20
    Turnaround with express DHL shipping: about four days or so, entirely acceptable. Thoughts:

    [​IMG]

    • lmao this is fun
    • 1.2mm is a pretty good pcb thickness for this.
    • making the notches slightly larger than the side connecting slot things was a good idea, but 10 mill would have sufficed. Notches connecting front panel to z axis tiles need to be bigger though, about 2mm or so
    • seems like it's 'roll a d6' mode to return soldermask results, easyeda doesn't entirely understand my weird requests. nothing a layer of paint wouldn't fix
    • my phone camera's real bad
    I will still be waiting a while for the standoffs and fasteners and chips and stuff, so it's not quite lego o'clock yet. I'm not convinced this was a bad idea yet though I've worked up a healthy dissatisfaction with my charge-and-input solution, so there's work to be done.
     
  6. Stitches 2 and a Half Dollarydoos Staff Member . .

    Joined:
    Feb 5, 2017
    Messages:
    1,016
    Likes Received:
    954
    Location:
    Australia
    Portables:
    6
    I think it's really slick. It fits together so cleanly
     
  7. nobble .

    Joined:
    Apr 30, 2017
    Messages:
    168
    Likes Received:
    230
    Location:
    Memesota
    Portables:
    9000+
    All good stuff! Can't wait to see that sexy pcb in your casing. I approve of heavy use of kapton tape to avoid shorts over components. We all learned from the GhadS2. <3
     
  8. ahrlad .

    Joined:
    Oct 29, 2017
    Messages:
    29
    Likes Received:
    20
    We did? I should tape over the ICs or the entire board? I'll have to avoid shorts because my troubleshooting strategy consists basically of 'throw all the stuff away and go back to the drawing board'

    If any of you guys wondered what seventy-two dollars' worth of chinesium fastener looks like, feast your eyes hereupon;

    [​IMG]

    Double plusgood sorted, labeled and bagged. Not in ziplocs of course, but still! Ask me in a while how good an idea it was to dive straight uncle scrooge-style into it
     
    Stitches and nobble like this.
  9. cheese the tallest memer in town Staff Member . . .

    Joined:
    Mar 2, 2016
    Messages:
    2,337
    Likes Received:
    2,205
    Location:
    Florida
    You don't need to cover the whole board, but make sure to cover anything with metal bits nearby, iirc the speaker fell onto a part directly below it and shorted something because it was left uncovered
     
    nobble likes this.

Share This Page

Loading...