MIPI DSI Display Shield/HDMI Adapter

Features

Supports 3/4 lane MIPI DSI displays.
DSI controller supports resolutions of up to 1080x1920 at 60 Hz refresh rate.
Converts HDMI video to DSI - letting you connect any MIPI DSI screen to your PC, Raspi or similar devices. Conversion works up to 720p@60 Hz or 1080p@48 Hz.
Built-in framebuffer with simple graphics stack, allowing to interface small microcontrollers, such as Arduino through 8-bit parallel or SPI busses
Sub-$50 BOM, including 4-layer PCB (@100pcs).
Powered through mini USB connector.
Embedded 32-bit CPU, available for user applications.

Project history

12/2013: Schematics & PCB done.
12/2013: Initial version of the firmware, works with Iphone4/4s screens on a FPGA dev kit.
02/2014: Got the PCBs and components.
02/2014: Test PCB assembled, drive both 3- and 4-lane screens.
07/2014: Started work on HDMI <> DSI conversion.
08/2014: HDMI convesion working for 640x960 Iphone4 screen.
08/2014: DSI core achieves 1080p @ 60 Hz (48 Hz with HDMI conversion).
08/2014: Rev 1.1. PCB design, schematics and firmware released.
06/2015: Prototypingr rev 2.0.

To do

Arduino interface/drawing commands (depending on demand).
Test external HDMI decoder with displays larger than 1080p.
Port Doom to run on the softcore CPU.

Hardware

The diagram below shows the main blocks of the design:

The FPGA: Xilinx Spartan-6-SLX9. Highlights: amateur-friendly TQFP144 package and built-in SerDes rated up to 1080 Mbits/s. The FPGA does pretty much everything in this project, hosting the MIPI DSI core, framebuffer controller with DDR memory, HDMI/DVI decoder. Everything is managed by an embedded Lattice Mico32 CPU.
DSI Level adapter: a bunch of resistors interfacing the FPGA's 1.8 V SSTL/LVCMOS I/O to DSI levels. More info in the FPGA section.
DSI connector: a standard 2x15pin 2mm pitch female connector with all DSI signals, power supplies and some GPIO pins for interfacing with the display. Since connector pinouts differ between displays the idea here is to use a tiny adapter board hosting the particular LCD's connector and its wiring.
DDR SDRAM, providing memory for the framebuffer, since most smartphone DSI displays don't have one.
HDMI input: slow version, using FPGA's ISERDES blocks (up to 1080p @ 48 Hz) or a fast one (1080p @ 60 Hz), based on Analog Devices' ADV7611 chip. The external HDMI decoder shares some pins with the SDRAM chip and the host interface, so the full HD - 60 Hz version can only work as a HDMI to DSI adapter.
Host interface: 12 pins wired to Arduino shield's IOH/IOL headers. Exact functions are not defined yet, I'm thinking about a 4-wire SPI interface and an 8-bit parallel bus.
USB UART a CP2102 chip providing USB UART, software bootloader and JTAG functionality for the FPGA.
Main power supply: integrated PMIC (TI/National LM26480). Voltages are: +3.3 V (HDMI input, USB, host I/F), +2.5 V (SDRAM and FPGA Vccaux), +1.8 V (DSI), +1.2 V (FPGA core).
LCD bias/backlight power suply: Most displays need some higher positive/negative votlage to operate. The board has a simple DC/DC converter for that purpose, producing symmetric voltage of up to +/- 6 V. The voltage can be adjusted for the particular panel by connecting a resistor between one of the DSI connector pins and ground. There is also a separate current driver for backlight LEDs, programmable by another resistor. Both DC/DC converters use a TPS61041 chip.

PCB Design

The DSI shield consists of two PCBs - the main board, where all the cool stuff is and a small adapter board, usually different for each display, connected through a 30 pin 2mm pinhead.

The main board is a typical Arduino shield. I routed the design on 4 layers, with the signals on the 2 outer layers, a contiguous ground plane and a split power plane. The DDR is placed right under the FPGA to simplify routing. SSTL to DSI level translator resistors are placed right next to the FPGA output pins to avoid stubs. All differential pairs are calculated for Z0=100 Ohm.

The adapter boards simply route the DSI lanes,...

Announcement
twl • 01/16/2018 at 19:54 • 7 comments

As you've probably noticed, there hasn't been too many activity on the DSI Shield project during the past year. Many people were asking me where to buy the boards, how to set them up for a particular display and so on.

Unfortunately, the amount of my spare time does not allow me to contribute to the DSI Shield enough to make it a viable product - that is manufacturing and shipping the boards, providing user support or adding new features. It's just too much for a single person doing this sort of stuff in free time (most of which is already devoted to KiCad development).

If someone of you is interested in manufacturing these boards or firmware development, let me know.

Tom
Rev 2.2a. KiCad PCB & Schematics published
twl • 08/24/2017 at 09:51 • 4 comments

I've just pushed the full schematics/PCB design of the latest revision of the board to GitHub. It took a while to convert them to KiCad...
Rev2.0 prototypes arrived
twl • 08/18/2015 at 16:10 • 27 comments

I've received a couple of Rev 2.0 prototypes. Iphone4 display is working fine, still waiting for Optimus E980 connectors though...
Revision 2.0 & commercial availabilty of the boards.
twl • 06/21/2015 at 23:08 • 26 comments

Hi all,
The prototype of Rev 2 PCB (see below) just went to production.

Some news:
- Boards will be manufactured and sold by Creotech. We are targeting $99 (+ taxes/shipping).
- Rev 2 board will support resolutions up to 1080p/48 Hz and work by default with Iphone4 and LG Optimus E980 displays. For other screen types (AMOLED Galaxy S3/S4, Iphone 5) there will be adapters (available later).
- New version will also come with a composite video input, foreseen for building FPV systems for drones/flying models.
Note that the initial V2 release firmware WILL not work as a graphics card for Arduino. Writing a graphics accelerator is a serious task and my time resources are quite limited...
Commericial availability of the boards
twl • 04/28/2015 at 08:43 • 17 comments

Hi all,
We've found an industrial partner to manufacture and ship the DSI shield boards. Before we start the production, we need to know how many people would be like to purchasing the boards and which display models should be supported out-of-the-box. Feel free to fill the Doodle below if you are interested:
http://doodle.com/uv283rp366prppnt
Cheers,
Tom
Galaxy S4 AMOLED screen working
twl • 04/14/2015 at 09:47 • 12 comments

We have a working Galaxy S4 AMOLED screen, 1920 x 1080. A QHD screen from GS Note 4 is waiting to be tested soon!
First release
twl • 08/16/2014 at 00:26 • 0 comments

The PCB design, FPGA and software sources for the first release of the DSI shield are now available on Github.
Enjoy!
HDMI to MIPI conversion working
twl • 08/05/2014 at 17:37 • 2 comments

HDMI to MIPI conversion is finally working, here's a video showing a Raspi driving an iPhone 4 screen.
Freshest sources coming as soon as I've cleaned them up :)

View all 8 project logs

Step 1

Build the hardware:

- Make/order the DSI Shield PCB.

- Solder it!

- Check the BOM, as not all components should be mounted.

- Make/order/design an adapter board for your screen.

- Connect the two boards together with the LCD. Power the system through USB.

- No smoke indicates probable success.

Step 2

Clone the repository:

git clone https://github.com/twlostow/dsi-shield

Install an LM32 toolchain. You may find one on Lattice website. There's a pre-built version for Linux (IA32) available here.

Download and install Xilinx ISE 14.7 Webpack from Xilinx website.

Step 3

Build the software:

- edit software/rev1/panels.h and set the panel type you wish to use.

$ cd software

$ make

This will produce the boot.ram file that the synthesizer will embed in the FPGA bitstream. The file contains both the panel initialization/HDMI handling code and the bootloader, so the LM32 application can be re-loaded at any time via USB UART.