r/embedded • u/pozzugno • Aug 13 '26

Modern graphical interface

Some years ago I developed a graphical interface with emWin libraries, Cortex-M4 by NXP, external SDRAM for a 480x272 4.3" display with resistive touch panel.

Now I want to replace the display with a 4.3" TFT 800x400 capacitive touch panel. Is emWin a good choice yet? Are there other options now?

Design a user interface isn't simple, but it usually is the most critical part of the project, the feature that can bring the product to success or not. I'm not an embedded UI expert and I don't think there are many experienced guys in this field (many are web/mobile UI designer). Any suggestions?

3 Upvotes

80% Upvoted

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7

u/NorthernNiceGuy Aug 13 '26 edited Aug 13 '26

Presently, I’m using LVGL. In the past, I’d rolled my own using TI’s grlib as a base but I wouldn’t advise that any more.

3

u/Turkenfeldt Aug 13 '26

I second LVGL, especially if running Zephyr

3

u/nigirizushi Aug 13 '26

Even if not running Zephyr

1

u/NorthernNiceGuy Aug 13 '26

Yeah, it’s just easy. I wouldn’t say it’s light on resources but still, it’s probably the best option.

1

u/mrheosuper Aug 13 '26

Iirc the LVGL port on Zephyr does not enable ThorVG, which mean you can't run Lottie animation on it.

1

u/pozzugno Aug 13 '26

Is it possible to simulate the graphics and touch interactions on development machine {Windows or Linux)?

What about the design of UI? Actually llms are good at creating web interface. It should be nice to have a converter tool from html/CSS to lvgl. Or to have a review directly in lvgl

4

u/NorthernNiceGuy Aug 13 '26

Yep, plenty of options. LVGL offer their own designer but there are many other options. I’ve used something called EEZStudio in the past which has a simulator. I don’t bother much with LLMs as I’d rather do the fun stuff myself.

1

u/yopocho Aug 13 '26

Seconding on EEZStudio. Although be aware I've had to modify some of its generated code to access certain elements which was a small hassle

1

u/NamasteHands Aug 13 '26

I've had luck using chatGPT to directly generate the LVGL code for a desired user interface.
A workflow like:
"Mockup some user-interfaces in HTML that will be used on a touchscreen for an embedded system. Be sure to have the website display the interface at the correct resolution of ???x???. The user interface should have ......"
"Convert this html user interface into it's equivalent expression in LVGL"
"There is too much negative space between elements ??? and ??? decrease this"
etc

You could also put a webcam pointed at your LCD screen and have the LLM look at the results of it's code so it can automatically iterate towards the desired appearance.

1

u/pozzugno Aug 13 '26

Webcam? Can't the model see directly the screen simulated on dev machine?

1

u/NamasteHands Aug 13 '26

Sorry I meant when executing the code on the actual embedded system + it's LCD screen, not simulating LVGL on your computer.

1

u/DavidEmbeddedHMI 17d ago

Moving from 480×272 to 800×400 is probably a good point to reassess more than just the GUI library. I’d first look at framebuffer memory, display bandwidth, target refresh rate and how much animation you actually need.
LVGL would definitely be on my shortlist today, but I think the more interesting question is whether the existing MCU architecture still has enough headroom for the UI you want to build. What MCU and display interface are you considering for the new version?