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STM32L4R9ZI-Eval External SRAM shortage for 800x480 TFT LCD Frame Buffer.

Ashvin Ramani
Associate III

We have the STM32L4R-Eval kit revision 01 as well as revision 02

We want to use STM32L4R9AI in our prototype, which was used in the above Eval.

The difference between these two versions looks like in revision01 U5 SRAM is populated but not working correctly; in revision02 it wasn't populated. Please Confirm.

We want to use STM32L4R9AI in our prototype, which was used in the above Eval and our prototype is not ready yet, So, we want to start our development using eval-kit and our product requires 800x480 resolution TFT LCD on RGB interface.

This is the list of challenges we are facing as per below:

1) As per our display resolution required frame buffer size for double buffering is around 2MB that can not be fit into internal RAM(640KB). So want to use external SRAM.

Now, we have two options:

2) Option1: Use external SRAM connected to OCTO SPI2 SRAM(U5 IC) but it was not originally populated because of some limitations as per its datasheet.

-> Is this limitation specific to the Eval kit only or same can be applicable to MCU as well which we want to use in our prototype?

->Is this limitation related to part IS66WVH8M8BLL-100BLI, because we are planning to use the same in our prototype?

3) Option2: Use external SRAM FMC interface but as per datasheet can not be used with RGB interface.

-> Please suggest any workaround.

4) Can we use an external OCTO SPI1 flash to store the frame buffer for TFT LCD or it should only use to store UI bitmap, image, and UI contains?

5) @ST Kindly suggest a possible solution to start our UI development with Eval-kit, We are planning to use TouchGFX for UI creation but looks like we don't have any external memory to store the LCD frame buffer.

6)Is this MCU series fine to go with 800x480 resolution LCD or are you suggesting any other one?

11 REPLIES 11
FBL
ST Employee

A section to describe all versions and differences between products will be added when updating UM2448.

Internal ticket number: 134337 (This is an internal tracking number and is not accessible or usable by customers).

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.

Ashvin Ramani
Associate III

@F.Belaid​ , Thank you for your answer.

But my question is still open, can you please answer it point by point from the original post starting 1) to 6)?

Thanks in advance!