Low cost micro for RGB

[Ricko]

Hi,

what are the lowest cost STM32 that support full graphics (static and minimal animation like a progress bar or spin control) with RGB/parallel interface (not DSI nor SPI)?

Is there perhaps a comparison table that addresses such display-related requirements to help select a micro?

If not, any tips, suggestions or guidelines would are much appreciated.

Thank you

[STTwo-32]

Hello @Ricko 

For that i suggest you to refer to our GUI silicon portfolio table and the GUI software available for stm32 display kits. That should be really helpful. After that and for price sélection, i suggest you to use the STM32McuFinder.

Best Regards.

STTwo-32

[Tesla DeLorean]

Painting a basic frame buffer tends to require FMC for external memory, LTDC to paint the rasters to a RGB output.

Tends to be larger pin count devices to account for the memory interface and the perhaps 24-bits of video data for the colour DAC

Low resolution screens can be accommodated with internal RAM, but as that expands so does the cost. As the resolution increases more data must be moved to paint frames at 50 or 60 Hz

The STM32F429 was one of the earlier models supporting SDRAM for frame(s) and graphics, and the LTDC. Prior people used DMA, or a graphic controller via the external memory interface FMC/FSMC

>>static and minimal animation like a progress bar or spin control

That's mostly library level stuff, you can spend money on them or DIY. ST has some simple line, dot, circle try implementations in some of their BSP. And did ship STemwin

https://www.st.com/en/partner-products-and-services/segger-emwin.html

https://www.st.com/resource/en/application_note/an4323-getting-started-with-stemwin-library-stmicroelectronics.pdf

[Ricko]

Thank you @STTwo-32 

I noticed on the GUI silicon portfolio that the SPI is used by quite a few micro families for resolutions of up to 480 x 272.

Do you know if SPI for those micros allows refresh without the tearing effect (i.e. refresh of the whole screen at once)?

If so, at what colour depth? Do they assume 8 bits per colour?

Finally, are small animations supported without seeing the tearing effect?

Thank you

[STTwo-32]

For such informations, i think it Will be better to ask such a question on a new thread in the touchGFX and GUI forum since our graphic experts and users may help you more for such information. 
Best Regards.

STTwo-32

[Ricko]

Thank you both :)

[Oleksii]

If you need to display a value or some small animation in response to events or changes in the menu screen, a STM32F072 and an ILI9486 3.5-inch screen (480x320, 8-bit bus) or a similar one will be sufficient.

I have such a setup that receives values from the CAN bus, displays them, and controls the equipment (sending commands via CAN).

[Oleksii]

[Oleksii]

link to the project for an example 

[Ricko]

Thank you both.

@Oleksiicould you share the display part number or link so I can see the details.

Thank you

[Ricko]

Thank you @Oleksii 

I see that it does show tearing effect (when refreshing the screen) and I cannot have that in the product I am designing, the display must refresh immediately and all at once without any tearing. So I was wondering if you are you using the Tearing signal (and despite that it cannot sync fast enough) or if you are not using the Tearing signal at all?

Thank you

[Oleksii]

There is screen flickering on the camera, but it does not exist in reality. Regarding the screen transitions (information board -> menu), you see the screen where everything is erased first, and then redrawn in real time.

If you implement a buffer and display it on the screen, you won't see this. However, this doesn’t bother me; the main part of the device is in information display mode, and the numbers and images change smoothly without jerking.

If something more powerful but inexpensive is needed, then STM32L431 might be a good choice.

[Ricko]

Thank you @Oleksii