Texas Instruments DLP LightCrafter pico projector reference design overview
Several reviews of pico projectors have already been published on Habré: Aiptek PocketCinema V60 and V100 , as well as SP-H03 from Samsung.
In this article, we will talk about a platform that allows you to develop embedded devices with a projection module - this is the reference design of the DLP LightCrafter picoprojector (DLP3000-C300REF) from Texas Instruments.
There are several technologies that underpin modern pico projectors: DLP (Digital Light Processing); LCoS (Liquid crystal on silicon) and LCD. We will not consider the last two. We’ll tell you a little more about DLP technology, which is used in our device.
The basis of DLP is a digital micromirror device - DMD (Digital Micromirror Device) - a chip on the surface of which there are several hundred thousand micromirrors assembled into a single pixel array.
Each of the mirrors can deviate in both directions from its initial position by a small angle (10-12 degrees), thereby initiating the “on” and “off” states. The light incident on the mirror will be directed to the optics or to the side (usually the cooling system). To display halftones, the mirror switches from “on” to “off” at high speed using pulse-width modulation.
As emitters, LEDs of red, green and blue colors are used.
Contents of delivery
The device itself was in a small box. No cables and software, everything must be obtained separately, but with the Internet and standard cables this is not a problem.
Inside was the following contents:
- Trigger input / output
- Mini usb
- Power connector
- Mini HDMI
- Power connector
- FPGA SPI Flash Programming Interface
- MSP430 / DLPC300 Flash Programming Interface
- On / off button
- Input Select Button (DM365 / Internal Test Pattern / HDMI)
- Ethernet PHY
- Fan connector
- Focus management
- Boot mode switch
- Micro SD card
Technical features of the reference design DLP LightCrafter (DLP3000-C300REF):
- LED light element RGB (LED light engine), luminous flux 20 Lumens
- High scan rate using DLP3000 native resolution (608 x 684)
- Sweep frequency up to 4000 Hz (binary image)
- Sweep frequency up to 120 Hz (8-bit gray scale)
- Demonstration of images and videos in WVGA resolution (854 x 480)
- Configurable trigger input / output for synchronization with cameras, sensors, etc.
- Embedded DM365 processor running embedded Linux
- NAND flash memory 128 MB
- Interfaces USB, Mini HDMI, UART
- USB API and host GUI
- Compact dimensions: 117 x 65 x 23 mm
The device is a “sandwich” of two metal-based boards. Nearby is an optical module with a radiator connected to the boards with flexible cables. The metal base simultaneously serves as a heat sink. The design is reliable and practical. All necessary connectors are located around the perimeter and on top. In principle, as it should be for development devices.
The EVM module consists of a processor board, a driver board, and a light emitter. DM365 is a TMS320DM365 multimedia processor based on Texas Instruments DaVinci technology. It is used to run Embedded Linux. FPGA - Altera Cyclone IV FPGA, it controls the mixing of video channels (HDMI or DM365), controls the inclusion of LEDs and internal buffers for quick display of patterns. DLPC300 is a DMD controller. The MSP430 manages power and LED drivers.
- Power can be supplied directly from the USB of the computer (but preferably from a separate power supply) by connecting to the connector on the bottom DC_IN board.
- The debug UART is connected to the Minijack-2.5 connector, but due to its absence, we simply soldered (red wires in yellow cambric).
- MiniUSB is a standard wire.
- HDMI - via MiniHDMI / HDMI adapter.
To work with EVM, Texas Instruments provides a cross-platform graphics utility that displays images and video from a camera / HDMI, and also allows you to update firmware.
There is also an example command line provided by the API.
Build software (Linux + rootfs) to boot from Micro-SD card
The manufacturer took care of the trouble-free assembly and launch of software for his device. A normal BSP is proposed, allowing you to get healthy binary images in a short time.
First you need to download and install Linux DVSDK from the link . But certainly version 4.02, in which there is support for DM365. The manuals say that the host must be ubuntu 10.04. But we easily migrated the installed SDK to ubuntu 12.04.
Further on the link you need to find DLP LightCrafter DM365 DVSDK (version 4.0), download and install. From the Changes subfolder with the installed files, you need to copy the files with the replacement files into the folder with the previously installed Linux DVSDK files.
The assembly is carried out by the Sourcery toolchain for ARM from Mentor Graphics. You can download and install it here . It is important not to forget to add the path to the toolchain prefix to the description of $ PATH.
The assembly is performed by a sequence of make, make all and make components commands. The u-boot, uImage and rootfs images are collected for use with an SD card.
To install all this on an SD card, there is a ready-made script mksdboot_lcr.sh, it is located in the bin folder.
After completing the script, you need to insert the card into the connector and move the switch closer to the connector.
Downloading takes a little longer.
Texas Instruments' new pico-projection device development platform, called LightCrafter, uses a digital light processor (DLP) built on MEMS technology with nearly half a million micromirrors to form an image. RGB light-emitting diodes are used as a light source, allowing to emit up to 20 lumens of light. And when using active cooling and a thermal management system, light with a power of more than 50 Lumens can be obtained, which allows the use of LightCrafter in various conditions.
DLP LightCrafter can be used as a portable projector with an HDMI input, as well as for projecting structured light patterns, complex lighting with the ability to change the working wavelength (from ultraviolet to almost infrared light).
The ability to project structured light patterns allows you to use LightCrafter to instantly characterize and recognize 3D objects without touching them. 3D scanning technology works by projecting a moving strip of light onto objects and then analyzing the measurements of the deformation of the reflected strip using the 3D shape reconstruction algorithm. This feature can be used in contactless fingerprint scanners to identify people. In addition to use for biometric, facial, dental and medical scans, DLP can be used in various applications: from industrial control systems to a variety of scientific equipment. By using an optional FPGA, you can increase the output frequency of light patterns to 4000 per second.
To implement 3D scanning, an external camera and software that implements the corresponding 3D processing algorithm are required. A customizable shutter I / O of the platform allows you to synchronize the capture of frames by the camera (as well as other peripheral devices) with the projected frames of the light pattern.
Developers can create, store and display projected images using a software interface (API) via USB or an easy-to-use graphical user interface (GUI).
The powerful TMS320DM365 digital processor and Linux OS on the ARM core allow you to develop a fully functional embedded system.
Thus, the use of the DLP LightCrafter pico projector in new developments allows us to shorten the design cycle, achieve a small form factor and obtain a low cost of the final equipment.
PS You can find out about other TI hardware solutions on our website in the Texas Instrument Technology for Electronics Development section.