Display board recommendation

[Sting]

I want to build a project to get an idea of how the uGFX library performs on a larger display board.  By larger I mean something around 7".  I am building an embedded electronic brewery, but I want to use a board that I might want to use in a production environment.  Since I am starting from scratch I can consider anything.  Is there a way to understand the boards supported by the uGFX system and the performance constraints?

[Joel Bodenmann]

µGFX has been supported to run on any platform. No matter what you choose, you will be able to use µGFX with it. The question is how much effort you have to put into it (eg. when you use something with existing ports and drivers that will save you a lot of time).

To give you better / more precise advice it would be helpful if you could tell us a bit more about what you want to do. For example: Will it just be a regular industrial grade static GUI or are you expecting to work with animations? Is the system only going to handle the GUI or will it have other jobs too?

Assuming that we are talking about a regular control device you might want to consider the very popular STM32 microcontroller family. The STM32F4 and STM32F7 microcontrollers are the most used ones by the µGFX community and this is what we mainly use ourselves for development. They have an integrated display controller (LTDC) which removes the need to mess around with a dedicated display controller. Furthermore, they provide hardware acceleration (DMA2D, ChromART) which allows doing fancy animations and stuff without killing the CPU. Another nice benefit is that you can use different LCD panels without changing the hardware: You can connect any RGB panel directly to the microcontroller. This means that you can start developing with a regular 4" or 5" display from an easy-to-purchase development board (eg. STM32F746G-Discovery) and simply plug in a larger panel once you feel the need.

I hope that helps. As mentioned there are many different things to consider.

[Sting]

Sorry, this isn't a stong area for me, I am just trying to sort it out to make better choices.  

Are you saying if I buy the  STM32F746G-Discovery card, after I get tired of the small area of the 4.3" display I can replace it with a larger one? 

[inmarket]

As an example, the stm32f439-eval board uses a 640x480 display. We are just writing a set of board files for it now.

[Joel Bodenmann]

1 hour ago, Sting said:

Are you saying if I buy the  STM32F746G-Discovery card, after I get tired of the small area of the 4.3" display I can replace it with a larger one? 

Yes, that's correct. The display panels you connect to the STM32 microcontroller (when using the LTDC) use a standard RGB interface. If the physical connection is the same (they are usually 40 pin FPC cables) you can plug in any panel that has an RGB interface - no matter what size and what resolution (note that the maximum resolution that the LTDC can handle is something like 1024x768 if I remember correctly). Those RGB interfaces are VERY common and the only trouble you will have is deciding which one you want to pick of all the thousands available
I have a friend who used an STM32F429i-Discovery board and replace the 2.4" display on there by a 5" display with a much larger resolution. It works very well. Same would apply to the STM32F746G-Discovery board: If the physical connections match, it's just a matter of plugging the new display panel in. Otherwise you'll just have to do some soldering magic or purchase an adapter board as these connections are almost always some kind of standard.

There are also other standards out there like MIPI or LVDS which would allow you changing the actual display panel itself at any time. However, they are less common among these "smaller" systems.

[Sting]

I think maybe I didn't give enough information   What I need is a board that I can connect to a device like a Zynq board where the zynq does all of the processing and then the graphics is output to some controller.  

One way to use this board is for the STM32 be a uGFX server and the main processor sends uGFX requests across a connection and all of the uGFX is done by the server leaving the main processor to do what it does best.

Is this what you had in mind?  Or how you use this board currently?

[Joel Bodenmann]

This is entirely possible and a very common technique. If you want to do it like this, we definitely recommend using am STM32F4 or an STM32F7. Note that only the newer models of the F4 have the built-in LCD controller & hardware acceleration.