cheyao/leptosis60Ultra flat PG1316 bluetooth split keyboard
Leptosis left is an open-source printed circuit board by cheyao, from the cheyao/leptosis repository on GitHub. It is a 4-layer board of 93.5 × 72.3 mm with 91 parts on 100 nets, routed with 550 tracks and 205 vias.
It is built around the BQ24075RGT, MAX17048X+T10 and 1N4148W. Its parts include 23 capacitors, 19 diodes, 19 switches, 12 resistors and 4 inductors. It belongs with the keyboards and input boards and the nRF52 and nRF5x boards of this library.
"Leptos" stands for "flat" in greek, added with the suffix is, it forms the word "Leptosis", signifying the most flat. This represents my long lasting desire for an real flat keyboard that is portable and light. The name is also quite similar to the latin word "levitatio", signifying levitation and thus light. (I'm bad at naming things lol)
Leptosis is an ultra flat split bluetooth keyboard. It's thickness will be ~7.5mm, and employs the compact miryoku layout. Using an onboard nrf module, it achieves an ultra long battery life.
| Left | Right |
|---|---|
 |  |
You can either use PCBA to fabricate the PCB, or reflow it yourself. I highly discurrage you to reflow the yourself if you haven't reflowed a aQFN package before - it's a nightmare to get right.
The PCB files are in the hardware directory, you need to buy one pcb for the right and the left. There is also a V-Cut panneled version in hardware/panel. It uses JLCPCB's 1.2mm JLC04121H-7628 stackup. Other stackups would require re-tuning of the USB data lines and antenna feed trace.
The case is in the CAD directory. Print out all .step files.
The software is in the firmware. Leptosis uses ZMK, allowing ultra long battery life.
After fabrication, solder on some jumpers onto the 4 test pads, and connect it to a JTAG connector (I'm using the ST-LINK). Download the bootloader from the newest action here and unzip it.
For stlink, install openocd and run the following commands:
openocd -f /usr/share/openocd/scripts/interface/stlink.cfg -f /usr/share/openocd/scripts/target/nrf52.cfg -c 'program <path_to_bootloader>.hex verify reset; shutdown;'For other JTAG connectors, please refer to your own documentation.
Now plug in a USB-C cable, and you should see a mass storage device called LEPTOSIS.
Download the ZMK config from this repo: https://github.com/cheyao/zmk-config/actions, drag the utf file to the mass storage device and you are done!
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| Qty | Value | Footprint | References |
|---|---|---|---|
| 18 | 1N4148W | Diode_SMD:D_SOD-123 | D1, D2, D3, D4, D5, D7, D10, D11, D13, D14, D15, D16, D17, D21, D22, D23 +2 |
| 18 | SW_Push | PCM_marbastlib-xp-choc:SW_PG1316S | SW2, SW3, SW4, SW5, SW6, SW10, SW11, SW12, SW14, SW15, SW16, SW17, SW18, SW22, SW23, SW24 +2 |
| 6 | 4.7uF | Capacitor_SMD:C_0603_1608Metric | C13, C14, C15, C16, C21, C22 |
| 5 | 100nF | Capacitor_SMD:C_0402_1005Metric | C8, C18, C19, C20, C23 |
| 4 | 10k | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R3, R6, R8, R10 |
| 4 | 15pF | Capacitor_SMD:C_0402_1005Metric | C1, C2, C3, C4 |
| 4 | 5.1k | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R1, R2, R15, R16 |
| 4 | TestPoint | TestPoint:TestPoint_Pad_D1.5mm | TP1, TP2, TP3, TP4 |
| 2 | 1.5k | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R5, R9 |
| 2 | 10uH | Inductor_SMD:L_0603_1608Metric | L2, L4 |
| 2 | 1uF | Capacitor_SMD:C_0603_1608Metric | C11, C17 |
| 1 | 0.5pF | Capacitor_SMD:C_0402_1005Metric | C6 |
| 1 | 0.8pF | Capacitor_SMD:C_0402_1005Metric | C5 |
| 1 | 100 | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R7 |
| 1 | 100pF | Capacitor_SMD:C_0402_1005Metric | C9 |
| 1 | 15nH | Inductor_SMD:L_0402_1005Metric | L3 |
| 1 | 2N7002 | Package_TO_SOT_SMD:SOT-23 | Q2 |
| 1 | 3.9k | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R4 |
| 1 | 32.768kHz 12.5pF | Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm | Y2 |
| 1 | 32MHz 12pF | Crystal:Crystal_SMD_2016-4Pin_2.0x1.6mm | Y1 |
| 1 | 4.7nH | Inductor_SMD:L_0402_1005Metric | L1 |
| 1 | 47nF | Capacitor_SMD:C_0402_1005Metric | C12 |
| 1 | 820pF | Capacitor_SMD:C_0402_1005Metric | C10 |
| 1 | Antenna_Shield | RF_Antenna:Texas_SWRA117D_2.4GHz_Left | AE1 |
| 1 | BQ24075RGT | Package_DFN_QFN:VQFN-16-1EP_3x3mm_P0.5mm_EP1.6x1.6mm | U2 |
| 1 | Conn_01x02 | Connector_PinSocket_2.54mm:PinSocket_1x02_P2.54mm_Vertical | J2 |
| 1 | LED | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D31 |
| 1 | MAX17048X | leptosis:WLP-8_1.67x0.93_P0.4 | U3 |
| 1 | NC | Capacitor_SMD:C_0402_1005Metric | C7 |
| 1 | SW_SPDT | leptosis:Switch_Sink_MINI_MSK12CO2 | SW31 |
| 1 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1 |
| 1 | USB_C_Receptacle_USB2.0_14P | PCM_marbastlib-various:USB_C_Receptacle_HRO_TYPE-C-31-M-14 | J1 |
| 1 | nRF52840 | Package_DFN_QFN:Nordic_AQFN-73-1EP_7x7mm_P0.5mm | U1 |
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This project is a keyboard that has the potential to have many different modules attached, modules such as displays, a rotary encoder panel, potentiometers, or a numpad! > [!NOTE] > Most of the features can be added due…
It measures 93.5 × 72.3 mm and has 4 copper layers, 1.14 mm thick.
91 parts, built around the BQ24075RGT, MAX17048X+T10 and 1N4148W. 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 cheyao/leptosis repository on GitHub, at the commit this page was made from: the board is hardware/left/leptosis-left.kicad_pcb and its schematic hardware/left/leptosis-left.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Its repository states no licence, so its author keeps all rights: ask cheyao before reusing the design.