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FABNOTES.md

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FABRICATION NOTES FOR MAIN 1.4 VERSION

  • Compared with 1.3 design you only need different LED modules (SK6812 Mini-E instead of WS2812 3535). Beware that this PCB uses the most common SK6812 Mini-E package, but there are many variants around including reversed wired one or similar packages with non addressable RGB. In doubt check the wiring in Kicad. If ordering on Aliexpress you should generaly be safe when looking for this part but always double check the pinout.

  • Beware that Gateron hot swappable sockets must be oriented properly with their rounded edge against the central hole. If mounted upside down you won't be able to insert the switch. Kailh sockets don't have the same symetry in their shape so no risk to mount them upside down.

  • Be careful when selecting your hot swappable sockets as all brands have normal and low profile options with different pin placements. You can only use normal sockets on the main 1.4 version. There is also a low profile version for Gateron KS33/V2 low profile switches that I haven't assembled yet. Use with caution!

  • I recommend you stick with recommended diodes 1N4148W in SOD123 package. Too small diodes can be a pain to orientate properly without proper magnification

  • Choose your MCU wisely: for wireless connectivity, Nice Nano V2 is fine and kind of the only option at this moment. But you'll loose some functionalities such as speaker, haptic feedback and less display used for logos. On the bright side I can confirm that both encoders do work flawlessly with recent versions of ZMK. When you wish to make the extra steps, ZMK firmware is a bit tricky to setup properly, but with some time you may be able to implement what you want. Keep in mind that the current official Firmware is based on an older ZMK codebase and some significant changes have happened recently, in terms of syntax, making it almost mandatory to do some changes in the original config and devicetree files (for instance in order to have precise pulses per rotation for each encoder or to enable RGB)

  • For wired builds I now only recommend RP2040 Pro Micro boards as it seems very compatible with QMK and much more powerful compared with ATMega32U4 MCU wich is outdated now. As I have recently ventured deeper into QMK, it appears that when using their latest toolchain and build definitions, the Atmega cannot hold all functionalities in its memory. So you'll definitely need to go the RP2040 route for a full set of specs. QMK is very good IMHO apart from not having proper wireless options which is a real bummer... It is also in the middle of a heavy transformation in its file structure (migration to a single keyboard.json for all metadata) and the provided stock firmware which is several year old will hardly compile at all against the latest QMK code base. So at the moment the easiest route is to flash the already compiled firmware or try ZMK.

  • The stock Pimoroni haptic feedback modules are extremly expensive at around 15 Euros each before shipping and are only offered by one single manufacturer. I have designed a DIY version of this module that should fit nicely. This module requires some SMD skills and equipment to be assembled. Parts values can be found on TI documentation for the driver chip itself. I will be using 2.2k pullup resistors and 1uF capacitors. Diode is optional and will serve as a reverse polarity protection. Same model as the rest of the keyboard could be used. Voltage drop should not be an issue as the driver chip will work with VCC ranging from 2 to 5.5V.

  • There are currently no neat and proper options for socketed MCU mount in order to keep a very low profile while being socketed. So far the best option is to use machined round pins female headers with some sort of wire or salvaged through hole part leg to act as male pins. The expected pin diameter matching the round female headers is around 0.5 mm. Complementary male round pins headers end up beeing a bit too high IMO. I am considering getting some 0.5 mm gold plated wire to act as male pins. Dedicated discrete machined pins in the correct size are outrageously expensive.

  • Power switch (The sliding one at the top) is only useful if you intend to use a battery as your main power source typically for a wireless build. I recommend to NOT populate it if your primary goal is to build a wired version of this keyboard. It will save you a little money. It serves no purpose at all for wired versions and can interfere with the enclosure and switch plates. It is also very delicate and not very ergonomic. The reset switch on the contrary will serve you every time you intend to flash your MCU, even when bootmagic is enabled it is always useful to have it.

  • You can choose to mount the reset switch, power switch and TRRS jack either side of the PCB. I think it is better to put them all on the upper side along with the rotary encoders, but the circuit is symetrical so they will work whatever side you choose apart from the minijack which has a specific requirement (see below). Most cases account for an upper side mount so just check with your case design. Stencils will provide openings to put paste on either sides so obviously use them (or not) as required.

  • Due to the way both sides communicate you should make sure you solder both minijack on the same side top or bottom in order to have a properly crossed RX TX pins between the two boards. This allows the use of serial full duplex protocol when using RP2040 boards with QMK.