Raspberry Pi CM4 Сarrier with Hi-Res MIPI Display

Description

Back in 2019 we developed a carrier board with Raspberry Pi CM3+ and a high-resolution touchscreen. We have been anxiously waiting for the CM4 ever since Raspberry Pi 4 became available. It's finally here! Now we're ready to develop a CM4-based module and make it available as an open-source project.

Details

The board will have:

standard RPi 40-pin header for peripherals and integration
connector with 4-lane MIPI DSI interface for display
connector with I2C interface for the touchscreen
micro-SD card holder
USB 2.0 host connector
PCM audio amplifier with 3W speaker output
USB-C power connector
micro-USB connector for flashing the on-board eMMC
general purpose push button
power and activity LEDs
mounting standoffs

All components are surface-mounted on one side, making the resulting assembly slim and good for wall-mount applications like a smart home dashboard.

There is a challenge to overcome: we need to hack our way through the undocumented MIPI
DSI peripheral to make the interface work. With the CM3+ module, we used an HDMI-DSI bridge, which is an expensive and hard to source component. This time we want to do things differently and connect the interface directly to the Raspberry Pi Compute Module. Broadcom and Raspberry Pi Foundation are hesitant to release the documentation for the peripheral and reserve this interface for official displays. However, the source code for the driver is available, giving us a good starting point. We may need to adapt it to our display and switch the interface from 2-lane to 4-lane mode to support the higher resolution.

Let's start hacking.

Files

PYXIS-CM4-BD-1.png

Block Diagram

Portable Network Graphics (PNG) - 82.31 kB - 01/05/2021 at 18:27

Preview

Download

Components

1 × Display

1 × Raspberry Pi Compute Module 4

1 × Custom board

Project Logs

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Week N. Sharing is caring
Igor Shturma • 07/26/2021 at 03:00 • 1 comment

After a long pause, I was finally able to get my hands on the project again. After some polishing, the design files are now ready to see the world:

https://github.com/renetec-io/cm4-panel-jdi-lt070me05000

Enjoy!
Week 12. New PCBs sent into production
Igor Shturma • 02/22/2021 at 05:01 • 5 comments
Week 11. Working on PCB Rev. 2
Igor Shturma • 02/15/2021 at 19:15 • 0 comments

Now finishing the board design in KiCad. I will share the project in the end after it is tested. The list of changes is under "Read more" link.

Meanwhile, check out my tutorial on DIY PCB assembly here:
Instructables: How to Assemble a PCB With Tiny SMD Parts
Read more »
Week 10. Touch and sound are now working.
Igor Shturma • 02/09/2021 at 03:10 • 0 comments
Week 9. Software stabilized.
Igor Shturma • 01/31/2021 at 04:34 • 0 comments

It looks like we got it working reliably now. As I promised in the last update, sharing the details of our software bring-up struggle, click "Read more" below the image if interested.
Read more »
Week 8. It is up and running!
Igor Shturma • 01/24/2021 at 02:12 • 0 comments

We got the image. Still, there is work to do, I will share the details later.
Week 7. Ready for bring-up.
Igor Shturma • 01/19/2021 at 08:12 • 1 comment

Assembled the board, the next challenge is software.

Read more »
Week 6. Getting ready to put the hardware together.
Igor Shturma • 01/11/2021 at 05:09 • 0 comments

Everything has now arrived: PCBs, displays, compute modules, components. Time to get hands dirty with the solder paste.
Week 5. PCBs ordered.
Igor Shturma • 01/05/2021 at 19:36 • 1 comment

An exciting milestone in the project was achieved right before New Year's Eve: the design is finished for the first PCB revision, time to order the boards.
Read more »
Week 4. The board architecture is finalized.
Igor Shturma • 12/29/2020 at 03:21 • 2 comments

We are now done with the architecture, BOM, and most of the schematic.
Read more »

View all 14 project logs

Discussions

Richard wrote 01/30/2022 at 23:26

I was wondering how difficult it would be to create a board that could drive a laptop screen to do away with the HDMI LCD driver board.

It would be something like the ebay listings advertised as "HDMI VGA 2AV Reversing LCD Driver Board for 13.3" LP133WH2 1366x768 LCD panel" but cutting out the HDMI cable, separate driver board, multiple power supplies etc

I have been looking at options for connecting a pi running magic mirror (or similar) to an LCD to put behind a mirror but making it as thin as possible.

Are you sure? yes | no

Dan Pastusek wrote 01/22/2022 at 21:15

Very cool project! Is there any way to buy one of these populated production boards?

Are you sure? yes | no

StonedEdge wrote 06/19/2021 at 10:02

This is excellent! I’m currently building a gaming handheld in the form of a Switch Lite and we would have absolutely have loved to use a 5.5” MIPI display with capacitive touch screen, but there is just no driver information available on anything right now, so we had to settle for HDMI and a 5” 800 x 480 panel (yuck).

I did think about using a MIPI HDMI bridge chip, but I hope some day direct driving the panels will become more accessible for us hobbyists. Awesome work, keep it up and I hope you could work on a 5.5” driven via MIPI someday too. I’d integrate it immediately lol

Here’s our project :)

Cheers,

Ben

https://www.raspberrypi.org/forums/viewtopic.php?f=98&t=289529&start=7

https://bitbuilt.net/forums/index.php?threads/retro-lite-cm4-a-stonededge-and-dmcke5-collaboration.3934/

Are you sure? yes | no

Brett Smith wrote 06/11/2021 at 19:58

Are any of the schematics, PCB files, or code available???

Are you sure? yes | no

Igor Shturma wrote 06/17/2021 at 06:02

Hi Brett, I got very busy the last month and had to put this project on hold. There is some issue that I need to find and fix in the last revision. Once I do this, I will share the files here. Hopefully, in a week or two.

Are you sure? yes | no

Brett Smith wrote 06/18/2021 at 03:40

Thank you, great work!

Are you sure? yes | no

Giovanni wrote 02/17/2021 at 05:57

Awesome, I've always wanted to use DSI on my RPi 3B+. It'd be interesting if there were an e-ink/Reflective LCD in that format- some Reflective DSI screens use 20pins, whereas the Rpi use 15. Nonetheless, It would be interesting to see more of those.

Are you sure? yes | no

ddB0515 wrote 01/28/2021 at 23:39

Such a nice progress, I have played for a while with touch digitizer for Nexus 2nd gen and made whole touch controller board for it based on Ilitek 2511, more details you can find here: https://budimir.cc/2020/04/21/asus-me571k-aka-nexus-7-2nd-gen-touch-digitizer-reverse-engineering/

Need to finish all optimisation for touch screen but I got it working :)

Are you sure? yes | no

nick4yy wrote 01/28/2021 at 11:27

great project, congratulations !!
is it possible to buy such an expansion board for CM4 ?

Are you sure? yes | no

Manny wrote 01/07/2021 at 06:45

Seems like a great initiative. Looking forward to your updates as you progress toward a first release.

Are you sure? yes | no

Raspberry Pi CM4 Сarrier with Hi-Res MIPI Display

Description

Details

Files

PYXIS-CM4-BD-1.png

Components

Project Logs

Collapse

Week N. Sharing is caring

Week 12. New PCBs sent into production

Week 11. Working on PCB Rev. 2

Week 10. Touch and sound are now working.

Week 9. Software stabilized.

Week 8. It is up and running!

Week 7. Ready for bring-up.

Week 6. Getting ready to put the hardware together.

Week 5. PCBs ordered.

Week 4. The board architecture is finalized.

Discussions

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