
Esp32-c6-pwm-4ch
thelad-dev/ESP32-USB-PWM-Board
ESP32-Firmware & Hardware für 4-Pin-PWM-Lüfter: Duty-Steuerung, Tacho/RPM, serielle CLI.

A physical chess board without the concept of turns
Kfchess is an open-source printed circuit board by misprit7, from the misprit7/real-time-chess repository on GitHub, published under the MIT licence. It is a 2-layer board of 240 × 240 mm with 235 parts on 225 nets, routed with 2,355 tracks and 301 vias.
It is built around the TEENSY 4.1, KF128-5.08-2P-AA and WS2812B-2020, with the AO3400A among its other parts. Its parts include 144 diodes, 32 resistors, 16 transistors and 9 ICs. It belongs with the NXP (LPC, Kinetis, i.MX RT) boards of this library.
Chess is boring. I'm boring too so I enjoy it anyways, but I can't help but think "I could design it better." Normally in chess players move sequentially in turns, but this introduces a huge latency bug that the developers of chess forgot to patch: you spend literally half the time waiting for your opponent!
The obvious solution is just get rid of the concept of turns in chess altogether and let players move whenever they want. Real time strategy games like StarCraft and Age of Empires are much more fun and spectator friendly than chess, so this should be a pretty uncontroversial minor rules update that can be implemented before the next world championship. To prevent things from getting too chaotic over the board each piece has an individual cooldown, so once it's been moved it can't move for a fixed period afterwards.
However there's an unfortunate roadblock to the widespread adoption of real time chess: as the Niemann controversy has made all too clear, chess is not immune from accusations of cheating through spectator assistance or outside analisys tools. Trying to have players self enforce these piece cooldowns is impossible. However where the intrinsic goodness of the human psyche fails, engineering is always ready to step in. This project is a physical chess board that keeps track and displays the cooldown remaining for each piece, and even physically holds them in place so no accidental cheating can occur.
The firmware and pcb kicad files are in this repo. For the physical design, see the design on OnShape. Other than those parts that were cnced, here were the off the shelf components used:
| Qty | Value | Footprint | References |
|---|---|---|---|
| 128 | WS2812B-2020 | LED_SMD:LED_WS2812B-2020_PLCC4_2.0x2.0mm | D11, D101, D102, D103, D104, D105, D106, D107, D108, D110, D111, D112, D113, D114, D115, D116 +112 |
| 32 | MountingHole_Pad | MountingHole:MountingHole_3.2mm_M3_Pad | H1, H2, H10, H11, H12, H13, H14, H15, H16, H17, H18, H19, H20, H21, H22, H23 +16 |
| 16 | 10k | Resistor_SMD:R_0603_1608Metric | R2, R4, R6, R8, R10, R12, R14, R16, R18, R20, R22, R24, R26, R28, R30, R32 |
| 16 | 1N4007_C727081 | footprint:SMA_L4.3-W2.5-LS5.0-RD | D1, D10, D19, D28, D37, D46, D55, D64, D73, D82, D91, D100, D109, D118, D127, D136 |
| 16 | 220 | Resistor_SMD:R_0603_1608Metric | R1, R3, R5, R7, R9, R11, R13, R15, R17, R19, R21, R23, R25, R27, R29, R31 |
| 16 | AO3400A | Package_TO_SOT_SMD:SOT-23 | Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13, Q14, Q15, Q16 |
| 4 | XY308-2_54-8P | footprint:CONN-TH_XY308-2.54-8P | U5, U6, U7, U8 |
| 2 | DB128V-5_08-4P-GN-S | footprint:CONN-TH_4P-P5.08_DIBO_DB128V-5.08 | U2, U10 |
| 2 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_Pad1.0x1.5mm | JP1, JP2 |
| 1 | 24_243_2 | footprint:CONN-TH_24.243.2 | U9 |
| 1 | KF128-5_08-2P | footprint:CONN-TH_P5.08_KF128-5.08-2P | U1 |
| 1 | Teensy4.1 | teensy:Teensy41 | U4 |

thelad-dev/ESP32-USB-PWM-Board
ESP32-Firmware & Hardware für 4-Pin-PWM-Lüfter: Duty-Steuerung, Tacho/RPM, serielle CLI.

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It measures 240 × 240 mm and has 2 copper layers, 1.6 mm thick.
235 parts, built around the TEENSY 4.1, KF128-5.08-2P-AA, WS2812B-2020 and AO3400A. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
From the misprit7/real-time-chess repository on GitHub, at the commit this page was made from: the board is ecad/board/kfchess.kicad_pcb and its schematic ecad/board/kfchess.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).