Update

Author: danic85

_posts/2024-12-13-raspberry-pi-cm5-flash.md

@@ -1,6 +1,6 @@
 ---
 layout: post
-title: Flashing a Raspberry Pi CM5 with Ubuntu 20.04
+title: Flashing a Raspberry Pi CM5 using a device running Ubuntu 20.04
 date: 2024-12-12 17:52
 category: [Raspberry Pi Compute Module 5]
 tags: [guide, cm5, errors]

_posts/2025-04-06-cm5-carrier-basics.md

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+---
+layout: post
+title: Designing a CM5 Carrier Board - A Practical Guide for Makers and Engineers
+date: 2025-04-06 18:51
+category: Compute Module 5
+tags: [raspberry_pi, cm5, carrier_board, guides]
+image: /assets/img/posts/2025-04-06-cm5-carrier-basics/thumb.png
+
+---
+
+Creating a custom carrier board for the Raspberry Pi Compute Module 5 (CM5) can seem daunting—but with the right tools and best practices, it becomes a highly rewarding venture. Whether you're building a robot, a smart display, or an embedded controller, a well-designed carrier board ensures stability, reliability, and full access to CM5's features.
+
+In this post, we’ll walk through both high-level considerations and practical tips for building your own CM5 carrier board—based on real-world experience and community knowledge.
+
+---
+
+## 🔧 Essential Resources to Get Started
+
+Before diving into schematics or layouts, gather these helpful files and templates:
+
+### ✅ Reference Files
+- **Raspberry Pi Official CM5 IO Board KiCad Files**  
+  [Download from Raspberry Pi](https://pip.raspberrypi.com/categories/1098-design-files)  
+  This gives you a solid reference for pinouts, layout, and component usage.
+
+- **Shawn Hymel’s CM4/CM5 Carrier Board Template**  
+  [GitHub Repo](https://github.com/ShawnHymel/rpi-cm4-carrier-template)  
+  Move the `hardware` folder into your KiCad base folder (usually in your Documents) for easy access.
+
+---
+
+## 🧠 Schematic Tips & Best Practices
+
+- **Use Hierarchical Sheets**  
+  KiCad lets you split designs into multiple sub-sheets for clarity and modularity. Use **labels** (especially global labels) to connect signals between sheets reliably.
+
+- **Library Management**
+  - When adding custom components (e.g., regulators, connectors), download both the symbol (`.lib`) and footprint (`.pretty`) from the manufacturer or Digi-Key.
+  - Add these libraries via **Project > Manage Symbol Libraries** in KiCad.
+  - Maintain naming consistency for smooth integration.
+
+- **Component Properties Matter**  
+  Update each part’s metadata (Manufacturer, MPN, Digi-Key/Mouser Part Number). These fields will be used when generating the Bill of Materials (BOM).  
+  _Tip: "Cut tape" is great for sourcing single units._
+
+---
+
+## ⚡ Electrical & Mechanical Design Considerations
+
+### 🪛 General Hardware
+- **Power Supply**: Provide 5.1V @ 5A via a VIN pin.
+- **Add a Power LED**: Simple, but valuable for diagnostics.
+- **Screw Mounts**: Include at least four mounting holes for mechanical stability.
+
+### 🔄 eMMC Boot Management
+To flash the CM5 when using onboard eMMC:
+- Add a **solder jumper between the `nBOOT` pin and GND** to disable eMMC boot.
+- This enables USB booting via the USB-C port—essential for headless devices.
+
+---
+
+## 🧩 Interfaces to Expose
+
+| Interface | Pins | Notes |
+|----------|------|-------|
+| **I2C**  | GPIO 2 (SDA), GPIO 3 (SCL) | Use pull-ups if needed |
+| **I2S**  | GPIO 18, 19, 20, 21 | Audio in/out support |
+| **SPI**  | GPIO 8, 10, 11, 25, 27 | Displays, sensors, Neopixels |
+| **UART** | GPIO 14 (TX), GPIO 15 (RX) | Connect GND to complete circuit |
+| **USB**  | USB-C (programming), USB-A (peripherals) | One USB-A port is usually enough |
+| **Camera/Display** | CSI, DSI ports | Make both accessible |
+| **GPIO** | 40-pin header | For compatibility with Pi HATs |
+
+---
+
+## 📏 Layout & Signal Integrity
+
+### 🧮 Net Class & Impedance
+
+- **Update Design Rules**: Set default track width and clearance to **0.2mm** to match the fine-pitch CM5 connector.
+- **USB Data Lines**: These require differential impedance.  
+  - Follow a **coupled microstrip line** design.
+  - Use tools or calculators (like Saturn PCB) to determine trace width/gap.
+  - Create a dedicated **Net Class** in KiCad for USB differential pairs (D+ and D−).
+
+👉 For more detail, check:
+[Octavo Systems USB Design Tutorial](https://octavosystems.com/app_notes/osd335x-design-tutorial/osd335x-lesson-2-minimal-linux-boot/osd335x-lesson-2-usb-circuitry/)  
+[Shawn Hymel’s CM4 Design Video Series](https://www.youtube.com/c/ShawnHymel)
+
+### 📌 Additional Layout Tips
+- **Fiducials**: Place two 1mm fiducials in opposite corners to help pick-and-place machines align the board.
+- **Connector**: Use a Hirose connector (the same one used in the CM5 IO board) for CM5 compatibility.
+
+---
+
+## 👉 Follow the Discussion
+
+Take a look at [this post](https://github.com/makerforgetech/modular-biped/discussions/118) on the MakerForge GitHub for a community-driven discussion on CM5 carrier board design. It’s a great place to ask questions, share your designs, and learn from others.
+
+## 🧪 Final Thoughts
+
+Designing a CM5 carrier board is a blend of electrical engineering, mechanical design, and a bit of artistic layout finesse. By using community resources, following standard practices, and taking time to carefully manage signal integrity and component sourcing, you can create a robust platform tailored to your application.
+
+Whether you're building a robotic platform like the Modular Biped or a custom embedded system, this guide should help you make smart, future-proof design choices.
+
+Happy prototyping!