Status
With the side-mounted display being chosen, I can now begin working on other aspects of the device. During Week 7, I have started to make meaningful progress on the project.
I pushed a commit on February 16, 2025 with the new case design and the unfinished display adapter PCB.
Case Design
I split up the case design into individual OpenSCAD files.
With the base file, I added multiple options for the display dimensions, so far it includes the DFRobot FIT0955 11.6" display, N140HCR-EN1 and N140JCN-GS9/-EEL display though I yet to receive the latter. I referenced the drawing in the datasheet for the N140JCN-GS9. The new case design focuses on the use of the N140JCN-GS9 display over the DFRobot FIT0955 display.
I noticed that Claude 3.5 is able to offer line completion for OpenSCAD files quite well, I noticed especially in the morning of February 16, 2025 that it has saved me hours of work. This technically has the hardware design of MediaCow Touch 2 partially AI-generated.
Display
On February 12, 2025, I came across the N140JCN-EEL/-GS9 display. Though large, I may be able to use this in place of the 11.6" display and still be able to 3D print the case parts whole. A custom PCB between the LattePanda Mu's display connector and the display is required with this display and others that have touchscreen data on the same connector as DisplayPort signals.
As mentioned, this display would have the device quite big. By comparison, the display in the largest Apple iPad is 12.9" diagonal while the N140JCN is 14". Tablets larger than this do exist.
On February 15, 2025, I designed a PCB that converts the 40-pin connector of the LattePanda Mu to the 40-pin connector of the N140JCN-GS9/-EEL.
Side-mounted Display and RGB-MIPI Bridge
I have found a display that I may be able to use for the side-mounted display. It requires an RGB-MIPI bridge, however.
The Tailorpixels TOH323XVT-01C may be used due to its short height, being less than an inch (25.4mm), which reduces the overall thickness of the device. It is also unique in that it is an AMOLED display. It appears to have been introduced in November 2024 with its datasheet being dated August 13, 2024, which is likely why I have not seen it before.
The RGB-MIPI bridge may be one of the most difficult parts of the project due to the lack of options. I still have major doubt about being able to implement the Rockchip RK628, leaving me with FPGAs. I asked on the EEVblog forums for advice on achieving this. A reply mentioned that GOWIN has MIPI TX IP cores available for use on their FPGAs.
The RGB-MIPI bridge may be on its own PCB, seprate from the carrier board, this is important in case I need to change the IC for converting RGB to MIPI.
I may design a module for the Banana Pi F2P that contains an FPGA and a connector compatible with the Tailorpixels TOH323XVT-01C that I plan to use. As far as I know, the RGB interface may be exposed through the GPIO header on the Banana Pi F2P. I responded about ordering samples of the Tailorpixels TOH323XVT-01C. I considered making a PCB that connects to the GPIO header on the Banana Pi F2P that has the FPGA on-board to convert the RGB signals to MIPI.
Side-mounted Button PCB
The side-mounted button PCB may continue to use the TI TCA8418 keypad controller. The current PCB design may still be able to be used as it is 28mm high with the case internal height being 30mm.
I made a revision to the board on February 16, 2025, mostly cleaning up some trace routing. Along with the "Cool S" symbol that I have been putting on PCB designs since MathPad in November 2022, I added the clover from OneShot due to the game's influence on the project.
Carrier Board
Recently, I had the idea to split up the design into multiple PCBs: display video bridge for the side-mounted display, eDP connector adapter for the main display, the carrier board, audio board and button board. This would significantly reduce the cost, complexity and potential waste in the case of needed changes. However, this may increase the complexity of the assembly process.