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USB 2.0

LattePanda Mu provides up to 8 independent USB 2.0 lanes.

  • Each supports High-Speed (480Mbps), backward compatible with Full-Speed (12Mbps) and Low-Speed (1.5Mbps).
  • All ports operate in Host Mode ONLY. USB OTG is NOT supported.

Design Guidelines

Pin Definition

Lane Name Pin Number Note
USB2_P1 67, 69 USB 2.0 Port 1
USB2_P2 73, 75 USB 2.0 Port 2
USB2_P3 79, 81 USB 2.0 Port 3
USB2_P4 70, 72 USB 2.0 Port 4
USB2_P5 109, 101 USB 2.0 Port 5
USB2_P6 112, 114 USB 2.0 Port 6
USB2_P7 76, 78 USB 2.0 Port 7
USB2_P8 82, 84 USB 2.0 Port 8

Restriction on USB2_P6

  • The default BIOS configures USB2_P6 specifically for use with USB Type-C port. So with the default BIOS, USB2_P6 port CANNOT be used directly as a generic Type-A USB 2.0 port.
  • To use it as a standard Type-A USB 2.0 port, customized BIOS firmware is required.

Polarity Check

The USB 2.0 controller does not support automatic differential pair polarity inversion.

  • Strictly ensure one-to-one mapping between the compute module and the USB device.
  • Do not swap D+ and D-. Incorrect polarity will result in communication failure.
+-----------------------+                    +-----------------------+  
|   Compute Module      |                    |      USB Device       |  
|      (Host)           |                    |      (Slave)          |  
+-----------------------+                    +-----------------------+  
|                       |                    |                       |  
|   [ USB D+ ] ---------+--------------------+---------> [ USB D+ ]  |  
|                       |                    |                       |  
|                       |                    |                       |  
|                       |                    |                       |  
|   [ USB D- ] ---------+--------------------+---------> [ USB D- ]  |  
|                       |                    |                       |  
|                       |                    |                       |  
+-----------------------+                    +-----------------------+

No AC Coupling

  • Do not place series AC coupling capacitors on USB 2.0 differential lines. Direct connection is required.

ESD Protection

Since USB ports are subject to frequent hot-plugging, they are vulnerable to Electrostatic Discharge (ESD). Adding ESD protection diodes on data lines is highly recommended.

  • Recommended Specifications:
    • Junction Capacitance: < 3 pF
    • Reverse Working Voltage: 5V (Minimum), 5.5V (Recommended)

Layout Guidelines

Parameter Requirement
Differential Impedance 90Ω
Intra-pair Skew < 15 mil
Reference Plane Continuous GND Recommended