Switchberry

Raspberry Pi Compute Module based, Managed 1G Ethernet Switch with PTP Support

Switchberry is a Raspberry Pi CM4–controlled Ethernet switching + timing platform built around a Microchip KSZ9567 and a Renesas 8A34004 ClockMatrix DPLL. It’s designed for PTP / SyncE / timing lab workflows while staying flexible enough to run as a compact managed switch/router with precise timing I/O.

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Order

Coming soon!!!

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Key Features

• 5× front-panel RJ45 ports driven by a KSZ9567 switch
• Raspberry Pi CM4 controller managing the switch over SPI
• Renesas 8A34004 ClockMatrix DPLL as the central timing hub
• Local TCXO reference for the ClockMatrix (drives derived clocks)
• OCP M.2 GNSS slot (GPS/GNSS timing card support)
• PCIe M.2 2230 slot (Wi-Fi 6E / Wi-Fi 7 modules)
• 4× rear SMA ports with muxing for multiple input/output routing options
• SyncE recovery from the switch into the DPLL (endpoint / boundary clock roles)
• PTP modes: hardware transparent clock (typical) or Linux DSA for software-defined behavior
• CM4 ↔ DPLL PPS routing supports both PTP Grandmaster and PTP client workflows

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Hardware Overview

Ethernet Switching (KSZ9567)

• Switch: Microchip KSZ9567
• Front panel: 5× RJ45 ports
• SFP: Present on KSZ9567 but unused in this design (not used because it doesn’t support PTP)

Controller / Host (CM4)

• Compute: Raspberry Pi CM4
• Switch management: CM4 controls the KSZ9567 over SPI
• Uplink path to the switch:
  • CM4 Ethernet MAC → KSZ9031 PHY → KSZ9567 (connected as one switch port)

Timing Core (ClockMatrix)

• DPLL: Renesas 8A34004 ClockMatrix
  • Central point for all timing signals (distribution, recovery, synthesis)
• Reference oscillator: Local TCXO
  • Feeds the ClockMatrix and serves as the base reference for derived clocks

Expansion

• GNSS: OCP M.2 GNSS slot for GPS/GNSS cards
• Wi-Fi: PCIe M.2 2230 slot for Wi-Fi modules (Wi-Fi 6E / Wi-Fi 7 capable cards)

Rear I/O (SMA)

• 4× SMA ports on the back panel
• Each SMA has muxing, allowing configurable input/output options depending on timing mode and setup

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Timing & Sync Capabilities

SyncE

• Switchberry can recover the SyncE clock from the KSZ9567 and feed it into the ClockMatrix DPLL.
• Enables operation as a SyncE endpoint or SyncE boundary clock (and equivalent roles depending on configuration).

PTP (IEEE 1588)

The KSZ9567 can be operated in multiple modes depending on the use case:

• Transparent Clock (typical):
  • KSZ9567 runs in transparent clock mode with hardware forwarding.
• Linux DSA (optional):
  • Run the switch under the DSA kernel architecture to behave more like a software router
  • Useful for experimentation with boundary clock / software-defined forwarding behavior

PPS Routing (CM4 ↔ DPLL)

• The PPS associated with the CM4 Ethernet port routes to the DPLL as both input and output.
• Supports:
  • PTP Grandmaster operation
    • CM4 disciplines to a PPS input from the DPLL, derived from GNSS or an external 1PPS source.
  • PTP client operation
    • CM4 recovers timing via PTP over the Ethernet switch and provides 1PPS to the DPLL.

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Typical Use Cases

• PTP networking
  • Transparent clock, boundary clock experimentation, lab deployments
• SyncE networking
  • Endpoint / boundary clock setups using recovered SyncE into the DPLL
• PTP Grandmaster
  • GNSS-referenced or externally referenced timing with PPS discipline
• PTP client
  • Recover PPS via PTP and feed the DPLL
• TSN experimentation
  • With additional scripting/development
• DPLL development
  • Clocking experiments, holdover testing, input qualification, output synthesis
• Arbitrary frequency generator
  • Using ClockMatrix outputs via configurable SMA routing
• PPS ↔ frequency conversion
  • Convert/derive timing signals via the DPLL and output routing
• Wi-Fi bridge
  • Wi-Fi 6E / Wi-Fi 7 connectivity via M.2 2230 (e.g., bridging/edge deployments)

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Notes

• The KSZ9567 SFP port is unused in this design because it doesn’t support PTP for the intended timing workflows.
• SMA functions are mode-dependent and determined by the mux configuration and ClockMatrix setup.

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License

This project is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).

You are free to:

Share — copy and redistribute the material in any medium or format Adapt — remix, transform, and build upon the material Under the following terms:

Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. NonCommercial — You may not use the material for commercial purposes. For full details, see: https://creativecommons.org/licenses/by-nc/4.0/

As the project creator, I reserve the right to use this material commercially or under any other terms.