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Witcher Wi-Fi Medallion MK2

Didn't like the metal necklace, so PCB art was the way to go.

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This project is based on https://www.hackster.io/12251/an-open-wifi-detector-with-esp8266-fe6951 and https://jcode.me/witcher-wi-fi-sensing-medallion-part-1/ . I screwed up while following Jason's tutorials and shelved this project for a long time (since 2016)And now I want to remake it to be a lot lighter and slimmer, using circuit board itself as the frame instead of metal medallion. I probably will have less chance of shorting the board out like I did last time.

The aim of this project is to explore the following topics:

  1. Use of SMD components
  2. Double-sided PCB making
  3. PCB art (Odd shaped circuit boards)
  4. ESP8266
  5. Programming
  6. Packing boards together for manufacturing
  7. Miniaturization
  8. Using KiCAD
  9. Not to mention fun

Disclaimer:

All materials (logo, symbol, typeface) are ® and ™ of CD Projekt S.A. and associated parties.

Author and/or this project is in no way sponsored, endorsed or affiliated by CD Projekt RED or CD Projekt S.A.

Not for sale. Personal and nonprofit use only. CC-BY-NC-SA.

For people who are going to distribute the finished board (which I assume isn't going to be many):

There must be absolutely zero monetary transaction while you distribute the boards. Do not remove "NOT FOR SALE" text. Keep in mind that this is using a copyrighted material as a part of fan project.

All materials are generated using KiCad and Adobe Illustrator CS6 using JLCPCB's design rules for ease of manufacture as it seems to be an industry standard rule-set.


About Components & Assembly

For the MOSFETs, make sure the pin 1 is Gate and pin 2 is Drain. Make sure the gate threshold voltage is lower than 3.3V and make sure it can withstand at least 200mA. (single-cell lithium battery protection boards use this part)

The crystal oscillator on the daughterboard needs to be affixed to the pad right behind it to prevent excessive vibration and temperature fluctuations.

The battery needs to support at least 250mA of sustained load and must have voltage rating of at least 4.2V.

There should be some marks to indicate what to do - such as signs which look like these:


There are two sets of symbol and an extra to show if you did it wrong:


Match the symbols on the board in that order and it should work just fine. All symbols should not be visible from outside when it's finished.
The power switch has been placed inside to prevent accidental activation, and reset and program switch has been placed near the edge of the board so it's not pressed when not required. You can press and hold respective buttons with a spudger, screwdriver or any stiff object.
Bridge the RX and TX jumper to enable the daughterboard's CH340G chip, or leave it alone to use external programmer.
By bridging U_PWR jumper, you can power this board with the USB connection. Else, you can use external power through the top UART port.

There are places where a mouse symbol is shown -- these are places where you can break the board off. Using side cutter or a knife cut or score the perforated edge and snap the board apart. Use file to smooth the rough edge down and add some nail varnish or resin to seal the edge.
Before continuing, wash the board with isopropyl alcohol (or rubbing alcohol) to wash off any residual chemical from manufacturing process. This is what is gonna be on your skin, after all. You don't want any copper salt, lead salt or any of the acid used in the process getting on your chest or your hands.

You can either hand-solder or use reflow oven and solder paste to assemble the board. (order SMD stencil if you are making more than 2)
Make sure the components are not falling off when soldering the other side; It's not fun to fix these kind of problems. For cheaper boards with maximum rating of 140 degrees centigrade, You must use low-temperature solder paste or hand-solder all the parts, in order to prevent the board from getting burnt.

WitcherMedallion_Rev16.zip

"Bekymmer utan lösningar"

x-stuffit - 4.58 MB - 09/23/2018 at 17:04

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WitcherMedallion_rev15.zip

Yes, it did! Here's a fixed version.

x-stuffit - 4.63 MB - 09/08/2018 at 05:40

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WitcherMedallion_Rev14.zip

It failed QA test so I modified the thing. This is gonna turn into a disaster, isn't it?!

x-stuffit - 1.91 MB - 08/28/2018 at 06:32

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WitcherMedallion_Rev13.zip

New board design. Hope it passes the QA this time!

x-stuffit - 1000.93 kB - 08/27/2018 at 18:38

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Medallion_FW_v1.5.zip

New version with watchdogs timer issue resolved.

x-stuffit - 6.55 kB - 08/27/2018 at 18:38

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View all 17 files

  • 1 × ESP-12F ESP8266 module The brain of the operation.
  • 1 × Resistor (10R, 1206) Motor current limiting resistor
  • 1 × 10uF Ceramic/Tantalium capacitor (1206) For the daughterboard - If you don't want it, you can omit it.
  • 1 × Micro USB socket For the USB-to-Serial daughterboard - If you don't want it, you can leave this out.
  • 6 × Resistor (10K, 1206) Pull-down resistors

View all 20 components

  • Rev.16 Update Log

    Torbjörn Lindholm09/10/2018 at 04:50 0 comments

    • Now MOSFETs have current-limiting resistors which can be used if you have MOSFETs with lower gate voltage (1.45V etc). By default the board aims for 2mA with voltage of 1.3V (R11 and R12 is 1K)
      • If you have MOSFETs with 3.3V gate voltage, you can simply add 0R jumper resistor or bridge the pad with a wire.
      • If you happened to order the board before it was fixed, refer to this picture:
      • Cut the traces with red lines, scrape the part marked with green and wire the resistors up as shown here.

    • Crazy value for pull-down resistors has been fixed. (R6 and R7 is now 10K)
    • Crazy value for LED and motor current limiting resistors has been fixed. (R8 is 82R and R9 is 10R)
    • Board layout has been tweaked slightly
    • Overall board size has been decreased for ease of manufacture


    This project has been going on for a really long time and I hope all this was for something...
    (Also I cannot finish the prototype boards because I did not receive all the parts)

  • Rev.15 Update Log

    Torbjörn Lindholm09/03/2018 at 04:49 0 comments

    Oops. Mistakes were made!

    • CH340G footprint has been changed from SSOP to SOIC. This was a mistake carried over from using other USB-to-Serial converter chips. (Kids, sleep well. Else things like this will happen!)
      • To fix the board if you happened to order the board before it was fixed, follow this diagram:
    • Regulator placement has been adjusted.
    • Crazy track found near C3, C4 and Y1 has been removed.
    • Board outline near the right ear of the backplate has been corrected to allow drills to pass through.
    • Batch number, date and vendor ID sections has been added for future use.
      • Use that for inventory tracking and other features.
    • The board outline has been rounded a bit. Now it shouldn't try to dig into your flesh. If it does, sand or shave off the sharp points with a box cutter, dremel tool, jeweler's file or sandpaper.

    That'll do for this update.

  • Rev.14 Update Log

    Torbjörn Lindholm08/28/2018 at 06:25 0 comments

    Small but fatal errors were found on the board and has been fixed.

    • 3.3V tracks had 0.2mm width. It has been corrected to 0.4mm.
    • Motor tracks had 0.2mm width. It has been corrected to 0.4mm.
    • LED tracks had 0.2mm width. It has been corrected to 0.3mm.
    • Copper islands that was not connected has been reconnected.
    • Incorrect footprint associations for jumpers were fixed yet again.

  • Rev.13 Update Log

    Torbjörn Lindholm08/26/2018 at 07:36 0 comments

    Pretty minor pre-flight check misses were found and fixed:

    • Crazy track found near motor MOSFET was found and removed.
    • Copper fill has been refreshed.
    • The component list has been updated.
    • Wrong component value for current-limiting resistor has been fixed.
      • Affected components:
      • R6 and R7, 47R and 10R respectively
      • To reduce the brightness, increase the value of R6 to 100R
    • The component list has been updated to reflect on the changes.
    • Speck of incorrectly placed track near the edge of the board has been removed.
    • A wrong value was used for R6. It has been fixed. (45R -> 82R) If that value were to be used, the current would be 28mA instead of desired 15mA.
    • The single SIP switch has been changed to more readily accessible MSK-12C02 clone switch. (Credits: mzst)
    • The position of the switch has been moved to more accessible area.
    • A little bit of pizzazz was added.
    • The board layout has been changed.
    • The snake-through track has been rerouted.
    • The little break-off tabs are now thicker to prevent it from falling off during manufacturing.
    • Board version has been updated.
    • Now the archive also includes firmware.
    • Firmware issue (watchdog timer issue) has been fixed, perhaps by an overkill solution.

    JLCPCB has contacted me about this board and I'm gonna have it manufactured. Time to go shopping for the components!

    Update: Shopping is done. Now we wait...

  • Rev.12 Update Log

    Torbjörn Lindholm08/21/2018 at 17:32 0 comments

    Sometimes you just have to look back and see what has become of this project.

    Oh wait, no. I was joking. Just an another update!

    • Completely overhauled the circuit
    • Removed charging circuit (power source changed - Li-Ion Booster pack required)
    • Attempts at panelizing PCB were done
    • Support pins are now data transmission lines too
    • Three-layer designs? Maybe?
    • Added on-board USB-2-UART adapter
    • Added ATTiny1634 blinkenlights
    • Removed blinkenlights (Not enough PCB space, schematic can be found in 8seg_blinkenlights.sch)
    • Revamped UART adapter design (Taken from https://github.com/NiceCircuits/modules_from_china)
    • Removed redundant parts
    • Fixed incorrect jumper footprint
    • Minimized component count
    • Update logs updated to update on the updates and to improve on wordings of updates, driving the point of updates to home and to put as many of the word "updates" in one sentence
    • Mouse bites added
    • Electrical mistakes fixed
    • Redone daughter board because it was mirrored
    • Euuuurgh
    • Imported the features from original daughter board back to this PCB
    • Added OSHW logo
    • [pain noises]
    • Electrical wiring tested somewhat, may or may not require cut tracks to make it work
    • Panelizing attempts were made
    • Uhhhhhhhh
    • This update log is getting very long but the Read More tag won't work for some reason so this will do

    To-do:

    • Figure out a way to mount the battery pack
    • Figure out what battery to use, since AA cells or 18650 is out of question... Perhaps few of those lithium AA batteries could work because their nominal voltage is higher
    • Oh wait, what about the 9V battery
      • Turns out linear regulators are really bad at being efficient
    • Hmmmmmm
    • Uhhhhh
      • Shoot
    • Find an engineer, my head is getting overloaded

  • Yikes!

    Torbjörn Lindholm08/19/2018 at 17:34 0 comments

    A fatal flaw has been identified on the power circuit and it's being fixed now. Also, now the daughter board will actually do something if you decide to populate it!

  • Oops!

    Torbjörn Lindholm08/18/2018 at 15:48 0 comments

    Turns out the format for the drill file was incorrect and the pre-made Gerber files are missing the component references, which is required. Please don't use the pre-generated files!

  • Revision 11 Update Log

    Torbjörn Lindholm08/18/2018 at 04:26 0 comments

    Minor compatibility fixes here:

    • Board outline has been redone properly to ensure 100% compatibility between other programs, no more ugly null component hacks here.
    • Ornamental backplate has been redone too to ensure compatibility between other programs. Please note that all footprints on the board is only for show and you are not supposed to solder stuff onto it, but if you really want, you can do that, I suppose. It won't do anything, though.
    • Spacer pins are added. Length is about 7.5mm and the black plastic piece must go inside the circuit board sandwich and soldered on both sides to add rigidity. Flush-cutting or dome of solder is required to prevent lacerations and damages to clothing and other delicate objects (such as human flesh). Silver or lead-free solder recommended to prevent leeching of lead metal.
    • Logo position has been moved and resized.
    • Typos has been fixed.

    Some warnings for people with sensitive skin:

    • Fiberglass board pieces near the mouse-bites or V-cuts (snap-off tab) can be sharp and strands may be irritating to skin. Sand and seal off the mouse-bites after it has been snapped off (if applicable).
    • Lead poisoning may occur if leaded solder is used to solder places where water, humidity, salt or sweat can come into contact (such as outside perimeter of the circuit). If you feel nauseated or dizzy, remove the board immediately from the body and seek medical attention.
    • Some board manufacturing processes may use non-lead-free processes and may have residual toxic chemicals. Wash each circuit board before wearing. (Isopropyl alcohol followed by dish soap will do, do this before soldering)

  • Melancholy

    Torbjörn Lindholm07/30/2018 at 13:41 0 comments

    Currently looking for some engineers who can verify that this board is at least fit for production. I was unable to source the QA tester locally and one mistake could cost me a lot, due to it being expensive to manufacture.

    Also, should I change the ESP8266 to ESP32?

  • Rev.10 Update Log

    Torbjörn Lindholm07/10/2018 at 17:53 0 comments

    This time the updates are slow but important.

    • Added charging pad for ease of use (Read the warning on Cmts.User)
    • Daughter board now has less copper to aid in signal loss reduction
    • Added Noncommercial symbol
    • Added graphic
    • Component orientations are now marked with dots (Read the Cmts.User layer)
    • Via stitching done (forgot to add that to Rev.9)

    Daughter board has footprints but don't populate them! They are there as a decoration. You can see how the circuit makes absolutely no sense whatsoever, with it disregarding design rule like you drink water.

    Now, all I have to do is have this tested somehow...

View all 18 project logs

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