Gowin FPGA - MIPI Display - Page 1
Forum section: electronics / general

author: up8051
author_rank: Frequent Contributor
timestamp: January 16, 2023, 11:10:19 pm
content: Hi,In one of my projects I use a 480x1920 LCD display (Hannstar HSD088IPW1) and a Tang Nano 9K module connected via HDMI/DVI interface.Connection:Tang Nano HDMI Output -> HDMI to MIPI converter -> LCD MIPI InputI would like to eliminate the use of the HDMI-MIPI converter, which only unnecessarily increases the cost of the system , and connect the display directly to the FPGA.LCD + converter cost about 70$ , 50%LCD, 50% converter.But I came across a basic problem of lack of information on how to properly initialize this display, the available documentation does not give details about the MIPI-DSI interface at all.The currently used HDMI-MIPI converter is probably based (blurred marking on the chip) on the Lontium LT6911C chip, but there is no data sheet for it.I am wondering how to approach this topic?Might try reverse engineering but I don't have a good oscilloscope to try to catch the MIPI LP mode transmission?Or maybe someone has experience with this type of MIPI displays?BR JarekC

author: up8051
author_rank: Frequent Contributor
timestamp: January 17, 2023, 04:25:58 pm
content: Maybe someone have datasheet for Lontium LT6911C?

author: mon2
author_rank: Frequent Contributor
timestamp: January 18, 2023, 12:20:15 pm
content: Hi. We have been reviewing something similar for some pending industrial designs so can share what little we do know. A steep learning curve for us as we are also new to FPGA deployment and Verilog. Making good progress with state machine use and loving the flexibility available to us with FPGA technology.MIPI Display = MIPI DSI.There are some gurus of this field on this forum - linking their pages:MIPI is an industry spec and documented with some membership only docs but most of the required information is now publichttp://www.electricstuff.co.uk/nanohack.html* a must read / view - reverse engineering of the ipod nano MIPI (single lane) display with Lattice FPGA (can be ported to other targets)* Mike is on this forum and this research has opened doors for this fieldGuarav's website is an excellent one and also must read:https://www.circuitvalley.com/2020/01/spi-mipi-bridge-fpga-verilog-hdl-ipod-nano-nano-lcd-iphone-mipi-lcd.html* he on this forum and recently posted his latest camera projecthttps://mightydevices.com/index.php/2018/02/mipi-dsi-tx-interface-for-ipod-nano-7th-gen/* inspired by the above, this DSI target is the ipod nano 7th gen displayEfinix offers a DSI kit which uses the iPhone 7 DSI display (4 lane) using their Ti60 kit* offers an excellent start with their demo code to drive MIPI displaysOur recommendation is to skip the HDMI to MIPI bridge idea and instead, just consider FPGA to MIPI DSI. Gowin / Efinix can support 1-4 lane MIPI displays.https://www.efinixinc.com/products-devkits-titaniumti60f225.htmlThe Efinix kit was a bit rough when first introduced to the market but since then has been refined with the sample code and documentation. They are now in sync (not the boy band) and the demo works fine. We are considering to review their latest kit which allows for 4 of video streams to be captured and displayed onto HDMI output. Just a FYI.You can study the commands used by Efinix / above articles to compare on how to initialize your target custom MIPI DSI display. The display vendor will offer the MIPI commands for initialization. The rest will be about using the FPGA to buffer a frame of data and stream out to the target as required and loop.If you plan to do any video manipulation such as alpha blending, etc. - not 100% sure if they are available from these vendors but likely something is available in public github projects.Hope this helps.

author: mblinov
author_rank: Contributor
timestamp: January 18, 2023, 12:38:33 pm
content: Not sure if you've tried this already, but I've had a surprisingly high success rate of just emailing the vendor asking for the full datasheet.It usually helps to hint that you're developing a prototype product, looking to potentially mass produce in the future (The key word is potentially - no lying there!)Weirdly, the far east vendors seem to be the most responsive to general technical inquiries in my experience.

author: up8051
author_rank: Frequent Contributor
timestamp: January 18, 2023, 03:16:34 pm
content: Compatible displays:- Hannstar HSD088IPW1 no direct contact for technical support, the form on the website reports an error in sending- GeSight Display JWX088IPW1 - Aliexpress Shop/Manufacturer did not answer the technical question- Winstar WF88BTYA8MNN0 - partial information from the distributor, waiting for completion- Multi-inno Technology MIT088-1 - I am waiting for information from the distributorI can't view examples from Efinix without buying and registering development kit.BR JarekC

author: mon2
author_rank: Frequent Contributor
timestamp: January 18, 2023, 04:13:50 pm
content: No one said it will be easy. We have been at this topic for over a year and only now making some progress.See attached which was found with our doctorate in google-fu from the school of Bolo Yeung. It will be a start.The above supplied links are a must read / view to get a grasp on the MIPI DSI interface.In short, every MIPI DSI display understands these commands but you will need to adjust the passed parameters for the target display resolution / timing.

author: up8051
author_rank: Frequent Contributor
timestamp: January 18, 2023, 05:18:44 pm
content: Another interesting document:https://silo.tips/download/demystify-dsi-i-f-application-report-abstractIt seems that I received a list of registers and values to be entered into controller buit in display,Part of the file:Code:SET_GCS(2);SPI_3W_SET_PAR(0xB0);SPI_3W_SET_PAR(0x5A);Delay_Xms(10);SET_GCS(2);SPI_3W_SET_PAR(0xB1);SPI_3W_SET_PAR(0x00);Delay_Xms(10);SET_GCS(2);SPI_3W_SET_PAR(0x89);SPI_3W_SET_PAR(0x01);Delay_Xms(10);...I was thinking about reverse engineering an HDMI-MIPI converter dedicated to this display.The LT6911C chip is configured by an external processor via I2C, so it is easy to see the transmission.I tried to register on the Lontium website but my account is still inactive.I found full documentation for this chip on csnd.net but I don't have an account and I need a Chinese phone number to register.Maybe someone has an account there and can download it:https://download.csdn.net/download/linuxunion/86246750BR JarekC

author: mon2
author_rank: Frequent Contributor
timestamp: January 18, 2023, 05:20:44 pm
content: Most offshore vendors are into their Chinese (Lunar) New Year holidays so do not expect a reply till at least after Feb. 1.There are other suppliers of HDMI to MIPI bridges such as Toshiba. Believe I have seen them @ Mouser and Aliexpress stores.

author: up8051
author_rank: Frequent Contributor
timestamp: January 18, 2023, 05:44:32 pm
content: I have LCD + converter at my desk, so can make tests.Lontium has many interesting chip, for exampleLT8911EX LVDS to eDP converterLT2911 LVDS to MIPI converter