Update README.md

Author: ziteh

Diff for: README.md

@@ -1,3 +1,52 @@
 # Calcite
 
-*Calcite52* - A 52 keys ortholinear keyboard, compatible with Kailh Choc low profile keyswitch.
+*Calcite52* - A 52 keys ortho keyboard, compatible with Kailh Choc low profile switch.  
+
+Powered by [QMK](https://github.com/qmk/qmk_firmware) and [Vial QMK](https://github.com/vial-kb/vial-qmk) firmware.
+
+## Features
+
+- USB Type-C.
+- 52 Kailh Choc low profiles keys.
+- Ortholinear layout.
+- Support [Vial](https://get.vial.today/), edit keymap and configure keyboard in real time.
+- Uses the [Raspberry Pi RP2040](https://www.raspberrypi.com/products/rp2040/) ARM Cortex-M0+ MCU, with 16MB (128Mb) external flash.
+- SRV05-4 chip for USB ESD (Electrostatic discharge) protection.
+- Resettable fuse to prevent power chort circuit and/or overcurrent.
+- RESET and BOOT buttons for RP2040.
+- One configurable LED (e.g. Caps Lock indicator).
+- USB D+/- pads for debugging.
+- 500mA 3.3V LDO regulator (RT9013-33GB, SOT-23-5).
+- JLCPCB's PCBA service available, no need to solder parts yourself.
+- M2 screws mounting hole.
+
+## PCB
+
+|        |               Preview                |
+| :----: | :----------------------------------: |
+| Front  | ![](https://i.imgur.com/gmzlI4C.png) |
+|  Back  | ![](https://i.imgur.com/0coQmdB.png) |
+| Layers | ![](https://i.imgur.com/m04crWC.png) |
+
+BOM and CPL `.csv` files for PCBA service are placed in [Releases](https://github.com/ziteh/calcite/releases) page.
+
+> Gerber, BOM and CPL files are generated by [KiCad JLCPCB Tools](https://github.com/Bouni/kicad-jlcpcb-tools) plugin.  
+> I use [KiCAD KLE Placer](https://github.com/zykrah/kicad-kle-placer) plugin to automatically place switch footprints.
+
+## Board Characteristics
+
+- Copper layer count: 2
+- Board thickness: 1.6 mm
+- Board overall dimensions: 231.14 mm x 97.79 mm
+- Min track/spacing: 0.13 mm / 0.13 mm
+- Min hole diameter: 0.3 mm
+- Castellated pads: No
+- Edge card connectors: No
+- Plated board edge: No
+
+## Disclaimer
+
+These files are provided without warranty of any kind.  
+It is recommended to check yourself before manufacturing and use.
+
+For the full statement, plase see [LICENSE](./LICENSE).