Connect Raspberry Pi 7'' Touch Display to STM32F769I-DISCO board?

[Sergius Reger]

Posted on October 02, 2017 at 23:58

Hello,

I'm trying to connect the Raspberry Pi 7 'Displays through the B-LCDAD-RPI1 adapter to the STM32F769I-DISKO BOARD.

Do you have an example of a project?

#stm32f769i-disco #b-lcdad-rpi1 #dsi #7 #raspberry"

[Angel Sanchez Garcia]

Posted on November 14, 2017 at 15:56

Hello.

I'm also trying to get this same configuration to work.

Is there some example, or at least some driver for the RPi LCD?

It makes no sense to me that ST is selling this adapter boards without any firmware support but I couldn't find anything at all.

[jLEE.14]

Hi,

I am also trying to get this same configuration.

Any progress?

[Tesla DeLorean]

I worked over the HDMI driver to get 800x600 and 1024x768 modes, among others, working via DSI. I have a B-LCDAD-RPI1 adapter and screen.

What have you done so far?

[Sumit_Kadam]

Hi, Can you please share excatly how you did it? The usage of B-LCDAD-RPI1 adapter and screen?

Regards,

[jLEE.14]

I found out it is not simple job. So i try to connect via parallel interface. It is easy and many example.

[TDJ]

@Sergius Reger​ Have you succeeded?

[Karan Kolhe]

@Sergius Reger​ Hi guys, Have you succeeded? @TJast​ @Sumit_Kadam​ 

[TDJ]

Hi @Karan Kolhe​ I have not succeeded yet. The problem is RPI displays are heavily protected.

1) Typically ICN6211 MIPI-DSI chip is used, no specs publicly available. However, lots of information can be found in Linux kernel forums. Based on this, I put configurator tool available here.

2) In addition to MIPI-DSI RPI displays use I2C communication for display config and touch. This communication is obfuscated. Note RPI displays contain some MPU, typically STM32F103. Probably the only purpose of this chip is to protect RPI secrets. What one can do is simply de-solder this chip and connect I2C lines (touch control and ICN6211. Doing so I have partially succeeded, I am able to communicate with ICN6211 and put in in test mode, display control screen, receive touch data. I have not succeeded yet configuring STM32F769 for ICN6211. If you do, please share the details/demo. For now I use MIPI parallel interface.

[Karan Kolhe]

Thanks for the quick response. Sure, I'll post it here as soon as I get it working. I have found this link where drivers are written for different display panels including raspberry pi touchscreen and OTM8009a which is used in STM32F769 discovery board. Currently I'm thinking of porting this driver of raspberry pi panel from same repository for STM32F769 using I2C and DSI Host. Please have a look because I'm new to device driver development for MIPI DSI display.

[TDJ]

@Karan Kolhe​ MIPI parallel interface (LTDC) is well documented. OTM8009a is not a problem, that is also well documented.

However, that is not a typical RPI display - and that is problematic due to lack of documentation and protection techniques used.

How I got it partially working? I took DF Robot DFR0550 display, desoldered STM32F103 chip, connected I2C lines directly (green and blue wires) and voila!

I also had to hard-enable step-up voltage converter (yellow wire), red wire was not needed - it connects the VDD track I broke for test drilling a hole next to display connector.

This Linux driver looks promising. Any success yet?

[Richard Lowe]

I would love to hear any progress on this. Also trying to use a similar 5" DSI Capacitive screen to a U5 through the B-LCDAD-RPI1 adapter.

Where would be a good starting point for something like this? Any direction from ST on this?