hw_ic_k2 — K2 PCIe Gen4 Converter Card (x8 → 2× x4)

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Open-source hardware — KiCad design files for the K2 converter card, the worker-side data-plane card in the IOCONVERT V2.0 1-Master-to-4-Worker chained NTB cluster. It takes one x8 host link and fans it out to two x4 MCIO ports, redriven for PCIe Gen4 signal integrity.

Preview

Top view of the fabrication release board (hw/k2_v4_8L.l4.kicad_pcb, 120 × 46 mm):

3D renders use KiCad stock models for standard packages. The MCIO (SFF-1016) and SlimSAS (SFF-8654) connectors have no vendor 3D models and are represented by simplified models derived from their footprint geometry.

Overview

K2 sits between the master host and the worker devices. A single SlimSAS x8 uplink carries eight PCIe Gen4 lanes; the card AC-couples and redrives them, then splits them across two MCIO 4i downlinks (4 lanes each). One DS160PR810 redriver handles each direction, and an on-board STM32G0B1 MCU manages sideband, out-of-band UART, I2C and the FRU EEPROM.

                8 lanes                       2 × 4 lanes
  Master ─────────────────►  K2  ──────────────────────────► MCIO 4i (J3) → worker
  (SlimSAS x8,              │    AC coupling + redrive
   SFF-8654, J2)            └──────────────────────────────► MCIO 4i (J4) → worker

                            U7 upstream / U3 downstream
                            STM32G0B1 MCU · 12V DC-in

Key Features

• Form factor: 8-layer PCB, 120 × 46 mm, 85Ω ±10% differential impedance
• Uplink: 1× SlimSAS x8 (SFF-8654) — 8 PCIe Gen4 lanes + 2 reference clocks
• Downlink: 2× MCIO 4i (SFF-1016) — the x8 link is bifurcated into 2× x4
• Redrivers: dual DS160PR810 (U7 upstream / U3 downstream), AC coupling per lane
• Management: STM32G0B1 MCU — sideband, OOB UART, I2C, FRU EEPROM
• Power: 12V DC-in → DC-DC 5V → LDO 3V3, plus 3.3V_AUX
• Debug: SWD header (J13), OOB UART header (J9)

Repository Contents

Path	Description
hw/	KiCad project (current 8L revision)
hw/sch/	Schematics: connectors, AC-coupling & ReDriver strap (up/down), MCU & sideband, power
hw/lib/	Symbol + footprint libraries
hw/data/	Netlist / project configuration (YAML)
archive/k2_v4_6L/	Historical 6L revision (superseded by 8L)
docs/	Architecture and manufacturing notes

Getting Started

1. Install KiCad 10.x
2. Clone this repository
3. Open hw/k2_v4_8L.kicad_pro
4. If symbols/footprints show as missing, add hw/lib/DS320PR1601.kicad_sym to the symbol library table and hw/lib/ForgeOS.pretty/ to the footprint library table (global or project-level)

Key Files

File	Meaning
hw/k2_v4_8L.kicad_pcb	Design source (frozen input)
hw/k2_v4_8L.l4.kicad_pcb	Fabrication release board (ready to order)

Documentation

• docs/01-architecture.md — What this card is
• docs/02-manufacturing.md — Stackup / process / delivery

License

AGPL-3.0 (see LICENSE)

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Part of the IOCONVERT V2.0 family: hw_ic_k1 (master gate card) · hw_ic_key (secure key vault)