NEC MPI4E Raspberry Pi Compute Module Setup Guide

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5 Miscellaneous Configuration Items

Note: Many of the options for the Raspberry Pi OS can be automatically configured using the

Compute Module Configuration Tool for Raspberry Pi OS see “Compute Module Configuration Tool for

Raspberry Pi ” on page 67.

5.1 Enabling the onboard USB 2.0 controller

The default settings on Raspberry Pi OS do not enable the USB 2.0 controller in host mode. This

prevents any USB peripherals, including the onboard USB LAN controller (LAN9514), from operating.

To enable the enable the USB 2.0 controller in host mode add the following line to the config.txt file:

dtoverlay=dwc2,dr_mode=host

5.2 Enabling 4K@60Hz video output

The default settings on Raspberry Pi OS do not enable the 4K@60Hz video signal format, and the output

format may be limited to 4K@30Hz.

To enable the 4K@60Hz format add the following line to the config.txt file:

hdmi_enable_4kp60=1

Note: For the best screen image use the display’s native 4K resolution of 3840x2160.

5.3 Configuring the correct HDMI video level encoding and decoding

The Compute Module can output video to displays that have video levels either in the range 0-255

(known as “full”) or in the range 16-235 (known as “limited” or “RGB limited”). Configuration settings for

the OS determine which range will be output. The NEC display can accept either range sets and will

display the video correctly, as long as it is correctly configured to match the video range from the

Compute Module. However, it is recommended to use the “full” range since it will give the maximum

number of displayable colors.

A mismatch between the output range from the Compute Module and the display will result in either:

• Blacks appearing as gray and whites being too dark.

o Cause: Compute Module outputs “limited” video range and the display is set to “FULL”.

• Dark gray levels being crushed and whites being clipped.

o Cause: Compute Module outputs “full” video range and the display is set to “LIMITED”.

The video range used by the display is configured as follows:

1. Navigate to the INPUT menu on the OSD.

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NEC MPI4E RaspberryPi 4 System on a Chip Solution