What is this?This controler replaces original controller of Leopold FC660C and makes the keyboard programmable.
This is supposed to be compatible to all models of FC660C as of 2019-05-03.

Check this thread for technical infos and discussion of the controller:
https://geekhack.org/index.php?topic=88439.0GB thread of past rounds(for the record):
https://geekhack.org/index.php?topic=88720.0Post your question or suggestion here.
Thanks
STOCKYES. This is still regularly available in stock and can be shipped in a few working days now. (2020-01-15)
ORDERPlease check this
notes on shipping under COVID-2019 pandemic before ordering. 2020-04-02
Instead, you can get it from
1upkeyboards now especially if you are located in the US and Canada. 2020-11-10
Email me at hasu@tmk-kbd.com with subject "FC660C Alt Controller" to place an order. Just let me know how many you need and your country. I'll send PayPal invoice to your email address.
Do not PM(Private Message) me.
The controllers will be available regularly and can be shipped in a few working days.
Price: 40(controller) +
6(shipping) =
46USD
For two controllers it costs 40*2 + 6 = 86USD.
Payment: I'll send you PayPal invoice, you can pay with credit card or balance of PayPal account.
Please make sure you supply correct shipping address when making payment.Shipping: Via Registered mail and usually takes two weeks. Trackable in most of countries except for Canada, Australia and China. Shipping cost is same rate for all countries as far as Japan Post can cover. Your item will be shipped within a week.
Shipping to CANADA is fast and reliable enough now. (2018/09/15)
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Shipping to CANADA: Sorry to say this but we had very long delay on delivery in Canada these days and it takes even two months occasionally when you suffer from bad luck. In the case of trouble you have to wait two months(plus a few week) before having me issue fully refund. If you are in Canada consider using EMS for shipping method, which is traceable and very fast(3 days or so) but it costs 20USD instead of 6
Let me know if you want to use EMS. How to installYou need only screw driver to install this controller. No soldering is required.
And take a look this video. Thank you, stoic-lemon!
https://youtu.be/TYmAb8zOPWU?t=3m6sOpen caseYou have to void warranty from manufacturer to do this mod, of course.
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Step 1: Void your warranty with getting rid of sticker and unscrew.
Step 2: Crack it open using tool like phone openner or plastic card with care.
Step3: Done!

Mate/unmate connectorCheck image below to know how to mate/unmate connector.
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I recommend you follow method proposed by manufacturer and this works certainly for me.
You don't need any tool to remove/unmate the connector use just your fingers. Plier and screwdriver likely slip off and make scratch and give cables damage.
To remove/unmate hold many cables as possible with thumb and index finger and wiggle the connector laterally each side within 15deg range.
To insert/mate just push both side edge of the connector parallel with fingers or nails.

Install controller boardJust screw down controller PCB on case.
How to remapKeymap EditorYou can use online keymap editor to get prebuilt firmware with your own keymap.

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There are two kind of prebuilt firmware.
Plain one has very simple keymap and would be useful as start point if you want to define you own keymap from scratch.
Emu one emulates FC660C stock behaviour, it would be nice if you like the stock keymap basically and need only small change.
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Plain:
http://www.tmk-kbd.com/tmk_keyboard/editor/unimap/?fc660c-
Emu:
http://www.tmk-kbd.com/tmk_keyboard/editor/unimap/?fc660c_emuLED controlCapsLock LED indicates CapsLock state naturally in both Plain and Emu firmware.
Insert LED never light up with Plain firmware, which suits for people who have no plan on the LED or regard it distractive. Emu firmware turns Insert LED on when Layer 1 is activated, you can you can place your keymap there and make it indicator for your keymap state.
Not a fan of these behaviour? You can do anything with the LEDs if you willing to write small code, of course.
Keymap Examples:- hasu's: spacefn and mousekey(Emu)
https://goo.gl/HfpRFdShare your keymap! Use 'URL shortener' button on keymap editor to get URL of your keymap and post it here.
You can grasp how this works by watching stoic-lemon's video.
https://youtu.be/TYmAb8zOPWU?t=10m59sHow to flashTMK FC660C Alt Controller has
ATMega32U4 as a microcontroller. To boot the microcontroller into programming mode push button on bottom of keyboard.
See wiki page on github for detail of flashing tool.
https://github.com/tmk/tmk_keyboard/wiki#flash-firmwareBuild from source codesYou can also tweak sources if keymap editor is not enough.
https://github.com/tmk/tmk_keyboard/tree/master/keyboard/fc660cSee this for detail.
https://github.com/tmk/tmk_keyboard/wiki#build-firmwareNOTE-
No plan for USB-C C is a bit too large to plug in USB-mini hole.
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No Bluetooth This controller doesn't support Bluetooth, USB only. And check
my thought as of July 2019.
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Not for FC980C This is not. See
FC980C Alt Controller thread.
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Not for FC660M It is not possible to replace its controller, which is integrated into one big pcb with all of switches.
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Actuation point adjustment Not officially supported. See this post.
https://geekhack.org/index.php?topic=88439.msg2403275#msg2403275-
For new 'Made in Japan' models The controller works fine with the new 'Made in Japan' model also. see this post.
https://geekhack.org/index.php?topic=88439.msg2621593#msg2621593TROUBLESHOOTCheck FAQ on wiki first.
https://github.com/tmk/tmk_keyboard/wiki/FAQhttps://github.com/tmk/tmk_keyboard/wiki/FAQ-Keymaphttps://github.com/tmk/tmk_keyboard/wiki/FAQ-Build-
Doesn't work with BIOS/UEFI https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-work-
Switching NKRO/6KRO https://github.com/tmk/tmk_keyboard/wiki/FAQ#nkro-doesnt-workUPDATE2017/04/06 GB OPEN:
https://geekhack.org/index.php?topic=88720.02017/05/01 GB CLOSE
2017/05/19 GB SHIPPED
https://geekhack.org/index.php?topic=88720.msg2427079#msg24270792017/06/29 Open thread inTMK Keyboard Service subforum
2018/05/21 Add Note for "Made in Japan" models and update stock
2018/09/15 Update error of pin configuration in documentation(PB7-> PB6).