#raspberry-pi #cm5 #carrier-board #cm5io #open-hardware #enclosure-design # Overview Reference sheet for the **Raspberry Pi Compute Module 5 IO Board (CM5IO), revision 2** — part numbers **SC1751** and **SC1967**. This is the board to design around: $20 list, fully open KiCad reference design, and committed to production **until at least January 2036**. Everything below is from Raspberry Pi primary sources (datasheet Release 2, product brief Dec 2025, PCN 25, IO Case product brief), not third-party summaries. Where a figure only exists as a drawing inside a PDF, the page is cited rather than transcribed. Related: [[Raspberry Pi CM5 Carrier Board Landscape]] · [[CM5 Carrier Boards with NVMe]] # Resources ## Open source design files Raspberry Pi publishes the **complete KiCad project**, not just a schematic PDF. This is a genuine reference design — the product brief states outright that it "is available as a reference design in KiCad format," and the datasheet says the files "can be used in your own reference designs." | File | Size | Link | |---|---|---| | CM5 IO Board, revision 2, KiCad files | 3.4 MB ZIP | [Download](https://pip-assets.raspberrypi.com/categories/1098-design-files/documents/RP-008099-DD-1-CM5%20IO%20Board,%20revision%202,%20KiCAD%20files..zip) | | rpi-cm5io KiCad (RP-007514-DD-2) | 3.4 MB ZIP | [Download](https://pip-assets.raspberrypi.com/categories/1098-design-files/documents/RP-007514-DD-2-rpi-cm5io%20Kicad.zip) | - Browse page: [PIP → CM5 IO Board → Design Files](https://pip.raspberrypi.com/categories/1098-design-files) - Short link: <https://rpltd.co/cm5io-design-files> - CM5 *module* design files (STEP models only, no schematics — it's a populated BGA SoM): [PIP category 1096](https://pip.raspberrypi.com/categories/1096-design-files) ### Licence Not Creative Commons and not CERN-OHL. Raspberry Pi's site-wide [design file licensing](https://www.raspberrypi.com/licensing/) is a permissive ISC/BSD-style grant: > Permission to use, copy, modify, and/or distribute these designs for any purpose with or without fee is hereby granted …with an AS-IS / no-warranty disclaimer. Note this is **separate** from the CC BY-ND licence on the documentation PDFs themselves — the docs are no-derivatives, the *hardware designs* are permissive. Commercial derivative boards are fine. ==One catch: the legal disclaimer in the datasheet says "RPL grants users permission to use the RESOURCES solely in conjunction with the Raspberry Pi products." Read alongside the permissive design-file grant that seems aimed at documentation reuse rather than the KiCad files, but worth a second read before shipping a derivative commercially.== ## Documentation | Document | Date | Link | |---|---|---| | CM5IO datasheet (Release 2) | 2025-09-02 | [PDF](https://datasheets.raspberrypi.com/cm5/cm5io-datasheet.pdf) | | CM5IO product brief | Dec 2025 | [PDF](https://datasheets.raspberrypi.com/cm5/cm5io-product-brief.pdf) | | IO Case product brief | Nov 2024 | [PDF](https://pip-assets.raspberrypi.com/categories/1097-raspberry-pi-compute-module-5-io-board/documents/RP-008186-DS-1-io-case-product-brief.pdf) | | PCN 25 — revision 2 change note | 2025-06-19 | [PDF](https://pip-assets.raspberrypi.com/categories/1168-pcn/documents/RP-008021-PC-3-PCN%2025_%20Raspberry%20Pi%20CM5%20IO%20board%20revision%202.pdf) | | CM5 module datasheet | — | [PDF](https://datasheets.raspberrypi.com/cm5/cm5-datasheet.pdf) | | Product page | — | [raspberrypi.com](https://www.raspberrypi.com/products/compute-module-5-io-board/) | | PIP product hub (approvals, PCN, design files) | — | [PIP category 1097](https://pip.raspberrypi.com/categories/1097-raspberry-pi-compute-module-5-io-board) | ## Where the drawings and images live No standalone PNG/JPG renders are published. The authoritative visuals are figures inside the PDFs: - **Dimensioned mechanical drawing (top + side)** — product brief, **page 4**. This is the one to work from for an enclosure. - **Mechanical layout with component placement** — datasheet **Figure 2, page 10**. - **Board photo** — datasheet **Figure 1, page 3**. - **Schematic block diagrams** — datasheet **Appendix A, pages 11–14**: Figure 3 top level, Figure 4 high-speed connectors (DSI/CSI, USB 3.0, HDMI), Figure 5 GPIO / Ethernet / SD, Figure 6 M.2 and PCIe power supply. - **Rev 2 silkscreen identification photo** — PCN 25, page 3. - **IO Case dimensioned drawing** — IO Case brief, **page 6**. ## Where to buy | Reseller | Price | |---|---| | [CanaKit](https://www.canakit.com/raspberry-pi-compute-module-5-io-board.html) | $20.00 | | [Seeed Studio](https://www.seeedstudio.com/Raspberry-Pi-Compute-Module-5-IO-Board-p-6303.html) | $20.00 | | [PiShop US](https://www.pishop.us/product/raspberry-pi-compute-module-5-io-board-rev-2/) (SKU SC1967, explicitly Rev 2) | $26.95 | | [SparkFun](https://www.sparkfun.com/raspberry-pi-compute-module-5-io-board.html) | $31.00 | Official list price is **$20** per the product brief. raspberrypi.com no longer shows a static price — it hands off to a reseller widget. PiShop is the only listing checked that names the revision. Also available as part of the [CM5 Dev Kit](https://www.raspberrypi.com/products/cm5-dev-kit/) at $195 (CM5 4GB/64GB wireless + board + case + cooler + 27 W PSU + cables). # Design ## Dimensions Board outline: **160 mm × 90 mm**. Accepts both CM5 and CM5 Lite. Mounting: **4 × M2.5** holes, per the IO Case assembly instructions (M2.5 × 4 screws, board to case base). The case drawing calls out a **2.7 mm** hole diameter, which is the standard M2.5 clearance. The product brief's dimension drawing (page 4) carries these callouts in mm — reproduced here as a checklist, but ==read them off the drawing before cutting metal; I have not verified which feature each unlabelled callout belongs to==: `160` `90` — board outline `77` `52.5` `61.5` `36` `22.7` `19.5` `18` `11.5` — X/Y positions `26` `25` `19` `15` `13.25` `11.25` `11` `8` — connector heights / offsets `3.5` — recurring, consistent with the standard Raspberry Pi mounting-hole edge inset Raspberry Pi's own caveat on that drawing: *"All dimensions are approximate and for reference purposes only. The dimensions shown should not be used for producing production data."* **For anything that has to fit, export from the KiCad project rather than scaling a PDF.** Open the `.kicad_pcb`, then File → Export → STEP (or VRML) for a solid model with real connector bodies and exact hole coordinates. PIP labels the Design Files category "Drawings, schematics and 3D models," but only the two KiCad archives are actually posted — there is no separate STEP download for the IO board. ## Connector and feature inventory | Interface | Detail | |---|---| | CM5 attach | 2 × high-density board-to-board connectors. Placement deliberately puts the module's on-board antenna at the board edge | | HDMI | 2 × full-size HDMI 2.0, 4K. 5 V supplied through a current-limited switch | | MIPI | 2 × 22-pin 0.5 mm pitch FPC, dual-purpose DSI/CSI-2. Pi 5-accessory compatible | | Ethernet | Gigabit RJ45 1:1 magjack with extra ESD protection. PoE routed to **J9** for a PoE+ HAT+ | | USB 3.0 | 2 × Type-A, VBUS limited to **~1.2 A combined** | | USB 2.0 | 1 × Type-C, data / `rpiboot` flashing. Host must supply enough power — use a powered hub if not | | PCIe | M.2 **M key**, PCIe **Gen 2 ×1 (5 Gb/s)** by default. Gen 3 ×1 (8 Gb/s) is "possible, but experimental and therefore unsupported" | | microSD | Push-push slot, **CM5 Lite only** — not wired for standard CM5 | | GPIO | 40-pin Raspberry Pi **HAT+** connector, 4 mounting holes. HAT must be oriented so it covers the RTC battery | | Fan | 4-pin JST-SH PWM, same connector as Pi 5 | | RTC | CR2032 socket, ~5 year typical battery life | | LEDs | Red = power OK, green = activity. Same behaviour as Pi 5 | | Power button | Same behaviour as Pi 5 | ## Power - Main input **J11**, USB-C. Negotiates **5 V @ 5 A** over USB PD by default. A standard Raspberry Pi 5 PSU works. - Alternative bare **5 V input via J8** — this is the one to use in an embedded build with its own supply. - If the PSU can't do 5 A, CM5 warns. Silence it with `PSU_MAX_CURRENT=5000` in the EEPROM config. - No 12 V barrel jack. Unlike the CM4 IO board, all regulation moved onto the module's Pi 5-style PMIC. ### Power button behaviour | Action | Result | |---|---| | Short press (running) | Brings up the shutdown menu; another press powers down | | Long press | Forces power down | | Short press (from shutdown) | Boots | ## Jumpers and straps | Header | Pins | Function | |---|---|---| | **J2** | 1-2 | `nRPIBOOT` — force USB boot instead of eMMC. Recovery path for a corrupt eMMC | | **J2** | 3-4 | `EEPROM_nWP` — write-protect the CM5 EEPROM | | **J2** | 6 | `SYNC_OUT` — IEEE 1588 timing signal, configurable as an input | | **J2** | 12 | `PMIC_ENABLE` | | **J2** | 13-14 | External wake/shutdown button | | **J3** | 1-2 | `WL_nDIS` to GND — disable Wi-Fi. **Not fitted by default** | | **J3** | 3-2 | `BT_nDIS` to GND — disable Bluetooth | | **J6** | both | Routes I²C from the GPIO header to CAM/DISP 1. **Both jumpers required** to use that port | ### GPIO Vref — R4 / R5 Default is **3.3 V via R5**. To run 1.8 V logic, desolder R5 and fit the resistor at **R4** instead. Only ever one of the two — fitting both can damage the board or attached devices. ## Camera / display asymmetry The two MIPI ports are not equivalent: - **CAM/DISP 0** — works standalone, and includes a camera power-down signal for energy saving. - **CAM/DISP 1** — needs both **J6** jumpers fitted to get I²C. When used as a camera, **no power-down control**. If a build only needs one camera, put it on port 0. ## Fan control The fan connector matches Pi 5, so any Pi 5 fan works. Important design note straight from the datasheet: > Fan speed is controlled with a PWM pin from CM5. When the board is powered down, the PWM pin stops sending this signal and, as a result, some fans might run continuously. If a custom carrier shouldn't spin the fan when off, **power the fan from the USB VBUS enable (U6)** instead — `VBUS_EN` is pulled low at shutdown. ## Reliability | Environment | MTBF | |---|---| | Ground, benign (lab / controlled) | **131,000 hours** | | Ground, mobile (vibration, thermal swing) | **15,000 hours** | Roughly 15 years vs 1.7 years. Worth knowing if the build ends up in a vehicle or anything that moves. # Configuration ## Revision 1 vs revision 2 Per **PCN 25**, transition June 2025. Reason for change: *"Improved fan control, minor BOM improvements."* | Category | Change | |---|---| | **Mechanical (form, fit, function)** | **No change** | | Electrical | Pull-up resistor added to the FAN output, so fans without an internal pull-up work — and so the fan is off during power-down, since `CM5_3.3V` goes low | | Electrical | LED driver simplified — superfluous buffer removed | | Silkscreen | Corrected `USB_OTG_ID` and `Sync_Out` labels | | Software / firmware | None required | **Identifying a Rev 2 board:** the silkscreen shows **`R2`** just below the "Compute Module 5 IO Board" graphic, itself below the Raspberry Pi logo, on the top face. Because form/fit/function is unchanged, an enclosure designed around Rev 1 fits Rev 2 and vice versa. The practical reason to specify Rev 2 is the fan pull-up — a Rev 1 board with certain third-party fans will run the fan continuously after shutdown. > ==Correction to earlier notes: the widely repeated "Rev 2 moved the fan mount so the heatsink and fan can be used together" claim does not match the PCN, which states no mechanical change to the board. That reporting appears to conflate the board revision with a separate IO Case revision. Trust PCN 25.== ## Matching IO Case (SC1966) $15. Two-piece sheet metal, includes a stick-on SoC heatsink pad and a PWM fan. | Spec | Value | |---|---| | Outer dimensions | **170 × 94 × 28 mm** | | Weight | ~350 g | | Material | Sheet metal | | Board fixing | 4 × **M2.5 × 4** screws (board to base) | | Lid fixing | 4 × **M3 × 4** screws | | Cut-outs | HDMI0, HDMI1, power, status, power in, SSD, Ethernet, USB-A, USB-C, SD card | | Antenna | SMA mounting hole in the base, rubber plug fitted by default | | Camera/display | Slots in the top for FPC pass-through | ### Case fan | Spec | Value | |---|---| | Input | 5 V DC (3.5–5.5 V) via the carrier's 4-pin fan header | | Start voltage | ≥ 3.5 V | | Power | 0.85 W | | Current | 0.18 ± 0.02 A | | Max speed | 8000 RPM ± 15% | | Max airflow | 2.46 CFM | | Noise | 21.7 dB | | Cable | 150 mm | **Fan connector pinout** (4-pin, 1.0 mm pitch, white): | Pin | Colour | Signal | |---|---|---| | 1 | Yellow | FG (tach) | | 2 | Black | − | | 3 | Blue | PWM | | 4 | Red | + | Assembly gotcha from the manual: stick the silicone pad in the base with its **upper edge flush with the bottom of the SD card slot**, or a microSD card can drop inside the case. # Decisions - **Design around Rev 2, but don't re-tool for it.** Form, fit and function are identical to Rev 1 — an enclosure or bracket works for both. Rev 2 only matters for fan behaviour at shutdown. - **Use J8 for 5 V in, not the USB-C jack,** for anything permanently installed. The USB-C port is better kept free for `rpiboot` flashing. - **Budget 5 V @ 5 A.** Not 3 A. And set `PSU_MAX_CURRENT` if using a smaller supply deliberately. - **Export STEP from KiCad; don't trace the PDF.** Raspberry Pi explicitly disclaims the PDF dimensions for production use. - **Put the camera on CAM/DISP 0.** Port 1 costs two jumpers and loses power-down control. - **Plan the HAT orientation early** — it has to cover the RTC battery, which constrains what else can live above the board. - **Design the fan rail off U6 / VBUS_EN** on a custom carrier if the fan must stop when the system is off. # TODO - ==Download both KiCad archives and diff them — PIP lists `RP-008099-DD-1 (revision 2)` and `RP-007514-DD-2 (rpi-cm5io)` as separate 3.4 MB files with the same update date. Unclear whether they are the same project under two part numbers== - ==Export a STEP from the KiCad project and save it to the vault attachments folder for enclosure work== - ==Confirm exact mounting-hole coordinates from the KiCad board file rather than the product brief drawing== - ==Check whether a Rev 1 board is still what ships from CanaKit/Seeed at $20 — only PiShop names the revision in its listing== - ==Decide 3.3 V vs 1.8 V Vref before ordering anything that hangs off the 40-pin header== - ==Re-read the "solely in conjunction with Raspberry Pi products" clause against the permissive design-file grant if this ever becomes a product rather than a one-off== # References - [CM5IO datasheet, Release 2](https://datasheets.raspberrypi.com/cm5/cm5io-datasheet.pdf) — primary source for everything in Design and Configuration above - [CM5IO product brief](https://datasheets.raspberrypi.com/cm5/cm5io-product-brief.pdf) — dimensioned drawing, p.4 - [PCN 25 — CM5 IO Board revision 2](https://pip-assets.raspberrypi.com/categories/1168-pcn/documents/RP-008021-PC-3-PCN%2025_%20Raspberry%20Pi%20CM5%20IO%20board%20revision%202.pdf) - [IO Case product brief](https://pip-assets.raspberrypi.com/categories/1097-raspberry-pi-compute-module-5-io-board/documents/RP-008186-DS-1-io-case-product-brief.pdf) - [Raspberry Pi design file licensing](https://www.raspberrypi.com/licensing/) - [Raspberry Pi HAT+ specification](https://datasheets.raspberrypi.com/hat/hat-plus-specification.pdf) - [Jeff Geerling — CM5 launch coverage](https://www.jeffgeerling.com/blog/2024/raspberry-pi-cm5-2-3x-faster-drop-upgrade-mostly/) - [[Raspberry Pi CM5 Carrier Board Landscape]] — the other 41 carrier options - [[CM5 Carrier Boards with NVMe]] — NVMe boot configuration and module SKU pricing - [[Raspberry Pi CM5 Cooling]] — heatsink and active cooler options, thermal data, IO Case fan conflict - [[SATA Storage on Raspberry Pi 5 and CM5]] — the M.2 slot takes 2280 cards, so an M.2-to-SATA bridge drops straight in