RPi CM4 - LiM Carrier Board series
The LiM Carrier Board series is a series of minimalistic Raspberry Pi (RPi) Compute Module 4 (CM4) Carrier Boards. Less-is-More (LiM) refers to the minimalistic design only providing the most rudimentary functionality to the CM4 such as 5V power via USB-C power connector and two status (power/activity) LEDs for the original LiM Carrier Board version. Additional + versions of the LiM Carrier Board will/might feature additional functionality such as flashing capability and SD card slot (see conceptual table below).
This is meant for CM4 boards with onboard storage (a future LiM version might sport a SD card slot for CM4 Lite modules) and wifi as this carrier board provides no other functionalty other than power and status LEDs.
Various LiM Carrier Board models
The first version of the LiM Carrier Board has been prototyped and more information can be found here. The second version, the LiM+ Carrier Board has also been prototyped, more info can be found here.
The LiM carrier board took about two months from idea (May 22nd, 2021) to delivery (July 14th, 2021). Special thanks to Anish Verma for working with me on the CAD designs of the carrier board.
The idea for such a minimalistic board was born from a conversation with Jeff Geerling when I asked him if he knew of a more minimalistic design than this board? He pointed me to to uptime.lab’s Upberry.
Neither of these boards are exactly what I was looking for for my use case. So insipired by Jeff I decided to design my own, customized board to my specs and that’s how the Less-is-More board came to be.
I forked this board design from Shawn Hymel. He has a two part youtube series where he goes through how to design a CM4 Carrier Board.
- Part 1 - How to Make a Raspberry Pi Compute Module 4 Carrier Board in KiCad
- Part 2 - How to Make a Raspberry Pi Compute Module 4 Carrier Board in KiCad
Feel free to modify this design for your own application.
Other iterations of the LiM board, inlcuding SD card tray and flashing capability are in the conceptual or prototype stages.
Here is the current conceptual list of planned boards:
| Model | Power (5V USB-C) | LEDs (Power/Activity) | Flashing Capability | SD card slot | Development Stage |
|---|---|---|---|---|---|
| LiM Board | ✔ | ✔ | ❌ | ❌ | prototype |
| LiM+ Board | ✔ | ✔ | ✔ | ❌ | prototype |
| LiM++ Board | ✔ | ✔ | ✔ | ✔ | abandoned |
While working onthe LiM++ Board I decided to move directions and add ac couple more features I could see of value. And so the LiM CM4 Cluster Carrire Board idea was born. The LiM CM4 Cluster Board has the following features:
- RPi Pi Compute Module 4 (CM4) support (both versions with and w/o eMMC - Lite version)
- PoE Gigabit RJ45 port (GbE)
- USB-C (USB 2.0) for CM4 module flashing (power + data)
- toggle switch for boot/flash mode
- microSD card slot
- 2232 and 2241 M.2 M-key socket dedicated for NVMe PCIe SSD drives
- Fan Pins
- SDA, SDC, YCC, GND pins for OLED Displays
You can read more about the LiM CM4 Cluster Carrier Board prototype here
More of my RPi musings and projects can be read on my l00nix’s RPi Musings Blog.
About
This project is maintained by Alexander Rau. The Raspberry Pi Compute Module 4 is a product of Raspberry Pi (Trading) Limited.
License
Schematic and PCB layout files are licensed under the CC BY 4.0 license.
Individual components and footprints found in the CM4IO library are licensed as per the Design Files license found here.
THE DESIGN IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS DESIGN INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS DESIGN.