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Raspberry Pi 4 Projector

This documents how to setup the DLP® LightCrafter™ Display 230NP evaluation module (DLPDLCR230NPEVM) with LibreELEC, a Linux OS distribution dedicated to run Kodi. The DLPDLCR230NP Evaluation Module supports the Raspberry Pi 4 with a software package (DLPDLCR230NPEVM_Python_Support_Code_Installer.exe) from TI that can run on top of Raspbian.

The three components are the:

Projector: DLPDLCR230NPEVM
Embedded computer: Raspberry Pi 4
Operating system: LibreELEC

DLP LightCrafter Display 230NP evaluation module

The Raspberry Pi communicates with the DLPC3436 display controller using I2C over the GPIO header. TI provides a Python library API and some example applications for the DLPC3436.

The Python support code requires export approval to download, and can be found here:

http://software-dl.ti.com/dsps/forms/self_cert_export.html?prod_no=DLPDLCR230NPEVM_Python_Support_Code_Installer.exe&ref_url=http://software-dl.ti.com/dlp/pico/DLPDLCR230NPEVM-SW

Links to user guide:

Raspberry Pi

The Raspberry Pi is configured by default to output 1920x1080, 60-Hz video via 18-bit DPI lines (RGB666) on the Raspberry Pi's GPIO header for the DLPDLCR230NP. These lines connect to the display module via a short ribbon cable. It's important the length of the cable is short, and that the Raspberry Pi's pin output strength is increased for this to operate correctly.

LibreELEC

The LibreELEC software can be found here (or mirrored in the files folder of this website):

git clone https://github.com/LibreELEC/LibreELEC.tv.git

Because LibreELEC is a bare bones operating system to only run Kodi, it does not come with all the tools required to setup the DLPDLCR230NP.

Additional software required:

Python files extracted from DLPDLCR230NPEVM_Python_Support_Code_Installer.exe
raspi-gpio from Raspbian
gpio from WiringPi module

Additional software for debugging:

i2cdetect

I built the projector using version 10.0.2:

https://github.com/LibreELEC/LibreELEC.tv/archive/refs/tags/10.0.2.tar.gz

Configuration

To configure the Raspberry Pi to output video on the DPI lines TI provides an example boot config.txt. This was modified to enable the vc4-fkms-v3d overlay which is required by LibreELEC.

config.txt

To run the python scripts that configure the projector for the Pi's outputted video there is a startup script to place in ~/.config/:

autostart.sh

DLPDLCR230 Python support files

These can just be copied to the home directory:

scp -r dlpdldcr230npevm_python_support_software_1.0 root@libreelec:~/

The I2C address should be updated in the i2c.py file:

DEFAULT_I2C_BUS = 22

Addons

To cross compile software on the PC to run on LibreELEC I first setup the build environment by creating the flash image from source:

docker run --rm --log-driver none -v pwd:/build -w /build -it -e PROJECT=RPi -e DEVICE=RPi4 -e ARCH=arm libreelec make image

This sets up the toolchains needed to compile the addons.

raspi-gpio

Copy the addons from here into the LibreELEC.tv/packages/addons/tools/ folder.

Enter a shell to manually compile the addon:

docker run --rm --log-driver none -v pwd:/build -w /build -it -e PROJECT=RPi -e DEVICE=RPi4 -e ARCH=arm libreelec bash

and then run:

./scripts/create_addon raspi-gpio

WiringPi

While still in the shell above run:

./scripts/create_addon WiringPi