Is there a connector standard for DSI compatible displays?

[HTD]

Let's say I have STM32H747I-DISCO discovery board. It comes with a 4" touch screen. Is it possible to connect a larger DSI compatible display to it using the connector on board? How should I even search for compatible larger LCD screens? What are the keywords I should use for search? From what I understand, to use hardware accelerated graphics, I should use DSI. Is there a standard for connectors, or for prototypes and experiments I just connect wires separately to the board pins? I guess not all DSI compatible displays are compatible with my board. So, how do you connect for example a larger, higher resolution screen? I've searched for DSI compatible displays online, but I couldn't find much information about the type of the connector they have. Looking at the pictures - I think the connectors look different from the one that comes with the DISCO kit. Are there any adapters for that purpose? How should I search for such adapters?

[K.Ata15]

Hey,

I've been through that level in hell 1-2 years ago. Before looking for connectors and compatible screen, please check the MIPI-DSI implementation of the h747. In short, you have two modes supported:

• Adaptive command mode, easy on the CPU, but needs expensive LCD with built in GRAM. Difficult to find, all Cube example drivers cover it(the one with the Disco board is this type)
• Video mode, almost all cheap IPS screens on AliBaba and AliExpress support this mode, but you have to add external SDRAM for video buffer. Nice and cheap screens available, but you have to code your own driver(good luck!)

In any case, you will have to design a PCB with correct connector, charge pump and impedance matching if you going to use full bandwidth on the mipi bus. My starting point was to design a small proxy PCB that plugs into the expensive 18Ghz connector and routing the signals to a FPC connector my LCD supported. It helped develop the driver and test the LCD suitability for my project.

[HTD]

What do you think about RPI dedicated screens? I've found a cheap adapter allowing connecting practically any screen for RPI DSI. Those are the more expensive ones, so - I assume they would support adaptive command mode. I've checked AliBaba, they have really cheap screens, but I would probably make my own driver for them. BTW, what about hardware drivers? For smaller resolution screens there are chips like RA8875 that take the pixel drawing on themselves. You connect the cheapest screens to them, but the whole tech is a little old now. Maybe they make universal driver boards for the newer, high resolution screens too? For what I've learned - I have 2 options - more expensive screen and less expensive software, or more expensive software and less expensive screen. For our first prototype we would probably go for the easier path to provide a nice shiny gizmo to show to the client, then we'll work on optimizing it to cut costs. A good design should have the last level of presentation layer isolated, so all it would take to cut the unit price would be making a display driver. I used to code demos on 8-bit computers back in the days, so... it would be fun if I ever have that much time on my hands 😉

[K.Ata15]

I think you need to spend the time and do you research right. For me the most important points for LCD selection was:

• needs to be high quality IPS panel with zero color bleeding
• i needed viewing angle of 175 deg or better
• 800x480 resolution for 5 inch display is the absolute minimum, but it kinda max outs the 747 with two DSI lanes (keep in mind some low pin count packages don't output the second lane)
• i have live 1024 point FFT control with lots of transparency and overlays, so hobby solutions like RAxxxx chip were not ok
• needs to be cheap
• the whole design needed to work out with two layer PCB, otherwise we taking about the next level of development costs and BOM

The important thing to remember is when you make a demo for your customer - they spend 2-3 hours a day on their smart phone with crazy good quality screen, faultless UI due to many coder-hours perfecting it. So the chances of actually impressing them with your 'compromise' solution is very low ;(