Does B-LCD40-DSI1 display on 32F769IDISCOVERY works with one lane.

[kD1]

1. I have used TouchGFX tool and implemented HMI where the configuration is with 2 lane. Now i want to work with single lane DSI configuration on 32F769IDISCOVERY to B-LCD40-DSI1 Display. Does this works ?
2. I have my own circuit designed by considering reference schematic from 32F769IDISCOVERY. Now i shall place New display with single lane DSI feature how could i validate DSI comm is correct or wrong. The issue might be hardware else software so how can i validate, is there any tool to test software is correct ?

Regards,

Kishore D

[MM..1]

When your display refresh and resolution dont exceed 500Mbit one lane then you can use it.

[kD1]

Hi,

    32F769IDISCOVERY - HMI is generated by TouchGFX 4.13 tool. I'm able to view GUI on LCD display on two data lanes using TouchGFX tool,  but the same project I have changed two lane to One lane & LTDC pixcel clock to 20.83 as [ 500/24 ] LTDC clock source. There is no response in screen after flashing.

if any example code on 32F769IDISCOVERY to B-LCD40-DSI1 of single lane please send me.

Regards,

Kishore D

[MM..1]

Try use lower pixel clock and some display drivers need set register init to use only one lane.

[kD1]

Hi MM,

Please provide in detail as am new in working with Display Interface.

1. Display Driver means the Display Controller Driver or Host Controller DSI Driver.
2. I have found for 800x480 display we shall require 2 lanes minimum but for 320x240 we require only one lane. Is this correct ?
3. Lower pixel clock = 500/24 = 20.83 is this ok ?

Regards,

Kishore D

[MM..1]

1.driver i mean part of software to initialize dislpay. Some LCD ICs have command to switch to one lane mode.

2.800x480X24X60 need two lanes but 800x480x24x50Hz = 460,8Mbit, that will work on 500Mbit one lane.

3.no 500/24 isnt ok, DSI need som data bits for headers crc sync usw. Your LTDC speed need be slower as max DSI rate. Too SDRAM speed and width is critical .

When you dont meet oncriteria from all, display or mcu dont work. And DSI can work in more modes, every have own criteria.

Basic calculations is for VIDEO BURST MODE. Real calculations need add porch numbers simply you need know basics.

Little example try display run on 30Hz Framerate:

910x560x30 = DOTCLOCK

DOTCLOCK x 24 for RGB888 mode = DSI data clock , but you need more or use max , unused time is low power for DSI bus

[kD1]

Hi MM,

Thanks for reply.

I got some idea with your response if you please consider my another request I will be very thankful.

We are using display of 320x240 connected to stm32f769 controller via DSI pin connector of our own schematic having all components just as similar to 769discovery board. Now I have designed all the screens in touchgfx tool. If possible could you please explain in detail the configuration need to change in st cube generator as I have tried to change resolution in ltdc to 320x240 but could not made possible, display is blank. If conveying through chat is very tough you can please explain the steps to change display resolution from 800x480 to 320 x 272 display.

Once again thanks in advance.​

[MM..1]

Hi kD,

your question is more complicated, to write details. Maybe start basic:

1. Change LTDC setup to porch and resolution.
2. Change LTDC clock setup to for example 60Hz refresh ... calculate dotclock
3. Choice location for framebuffer internal or external SDRAM...
4. Change resolution on touch setup and in touch project usw.
5. Check and change driver for display init

But better is as first run display without touchgfx parts.

For testing DSI use after all init before rtos start patterns gen HAL_DSI_PatternGeneratorStart(&hdsi, 0, 1);

[ELee.9]

Hi, I'm really interested in this topic.

Did you finally work sucessfully using one data lane with B-LCD40-DSI1?

I finally worked in one data lane in Low Power Mode, but still not working in High Speed Mode.

Could you please tell me how to do?

Thanks.