LattePanda Mu Schematic Sheet

Before reading further, you can watch the companion video where I demonstrate how to set up and document the schematic sheet that hosts the LattePanda Mu compute module. The video walks through placing the module symbol, adding supporting components, and defining hierarchical labels for inter-sheet connectivity.

Introduction

This guide explains how to implement the LattePanda Mu schematic sheet, which forms the core of the LattePanda Mu Carrier project. The compute module is the heart of the system, interfacing with every subsystem on the carrier board—such as power, USB, HDMI, Ethernet, and fan control. The schematic work here defines all logical connections between the module and the rest of the board.

Creating and Configuring the Sheet

Begin by creating a new hierarchical sheet named LattePanda Mu Module. Open this sheet in the schematic editor and place the LattePanda Mu component symbol from the imported library.
This symbol represents the compute module and includes a large number of I/O pins for high-speed interfaces and control lines.

Verify that the pinout matches the official LattePanda Mu Carrier reference schematic available on GitHub. This ensures that all signals are correctly mapped to the module’s connector and will match the LattePanda documentation during debugging and PCB layout.

Adding Pull-Down Resistors

Several pins on the LattePanda Mu require pull-down resistors to maintain proper logic levels during boot and suspend states.
These resistors (typically 100 kΩ) connect certain GPIO and control signals to ground, ensuring stable operation.

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Place each pull-down resistor according to the reference schematic and label them clearly—for example, R71, R72, and so on. Double-check each connection to confirm that critical control signals, such as power-enable and sleep management lines, are properly biased.
An incorrect default logic level on any of these pins may cause unreliable startup or erratic sleep behavior.

Adding Hierarchical Labels

After completing the passive network, you can begin adding hierarchical labels.
These labels allow signals from this schematic to connect logically with other sheets in the project.
Each label must use the same naming conventions as the LattePanda reference schematic to ensure compatibility when sheets are linked.

For example:

These labels provide the link points between the LattePanda Mu sheet and other subsystems, such as USB, Ethernet, power supply, and GPIO expansion. They make it possible to route and manage complex interconnections cleanly across multiple schematic sheets.

Exposing Labels on the Root Sheet

After all labels have been created, open the root schematic and use Place → Sheet Pins to expose them along the perimeter of the LattePanda Mu module block.
KiCad automatically generates pins for each label you defined, making it straightforward to connect them to matching signals on other sheets later.
You can adjust their positions at any point for readability once all subsystems are in place.

Verifying and Annotating the Sheet

At this stage, review your schematic carefully. Ensure that:

• All hierarchical labels are named correctly and point in the right direction (input, output, or bidirectional).
• Resistors and test points, such as R77 or TP7, are annotated according to the reference schematic.
• No nets are left floating or unconnected.

Manual annotation is preferred because it maintains consistency with the LattePanda reference design, which simplifies cross-checking and debugging later in the design process.

Copying On-Sheet Documentation

The official LattePanda Mu reference design includes valuable on-sheet documentation.
Copy relevant notes and text boxes into your schematic—especially those that explain pin functions, power states, or high-speed interface details like HSIO signals.
Avoid copying redundant or outdated notes to keep your schematic clean and readable.

This documentation serves as a built-in reference that explains why certain pins are unused, how suspend behavior works, or how differential pairs are managed.
It is particularly useful for learners and for future debugging sessions.

Saving and Next Steps

Once all components, labels, and documentation are complete, save the schematic.
The LattePanda Mu schematic sheet now functions as the central node of the carrier board design.

In the next stage, you will connect this sheet to the remaining subsystems—including the Power Supply, USB, Ethernet, and GPIO sheets—using the hierarchical labels you have just created.
This marks the completion of the first major schematic module in your LattePanda Mu Carrier project.

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