TFT driver INternal memory

[erwann]

Posted on July 31, 2012 at 17:28

Hi all,

To begin I have compiled AN2790 and AN3241 application note, to try understand logic code. These notes explain how use TFT with firmware ST. I have several questions about it. Is it possible, to display a picture (.bmp 16bits 320*240) don't use external SRAM? I think external SRAM is used like frame buffer in firmware ST. In other way can I stock my picture in internal flash memory and use FSMC bus connected to my screen ? I need to have only one chip for my project, the STM32 ARM.  

http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00278141.pdf

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http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00201397.pdf

#tft-driver-internal-flash-fsmc

[Tesla DeLorean]

Posted on July 31, 2012 at 18:04

What STM32 part, they make dozens?

Do you have 150 KB of memory available? If you don't have it internally, you'll need it externally, or use an LCD with it's own controller with memory. I'm pretty sure you can DMA out of FLASH just the same as you can out of RAM.

[erwann]

Posted on August 01, 2012 at 08:53

In fact in AN3241 ST explains that firmware (based for STM3210e-eval board) uses an external memory like frame buffer. I want just delete this part (externe memory) of firmware.

In AN2790 ST uses a firmware similar to display a picture which located in : -Flash (interne) or -SRAM (interne) or -Flash (externe) or -SRAM (externe) But ST doesn't explain if an other external SRAM for frame buffer is necessary. I want be sur I can used my internal flash to display my picture ? PS: I have attached two notes applications concerned in my first post

[Tesla DeLorean]

Posted on August 01, 2012 at 19:47

You should be reading the panel specs.

The panels ST uses on it's dev board send a stream of data to the panel via DMA. The source can be RAM, FLASH, EXT, the destination FSMC address space. If you have 150KB of flash to burn, put the image there. People use RAM buffers when they want to paint different images, or draw, on the screen. People use external memory so it doesn't contend with access to the CPU's more closely coupled memory. Why don't you get a dev board and experiment?

[erwann]

Posted on August 03, 2012 at 09:41

Thanks a lot clive1 !

I have buy a stm3210e-eval board. Like I am beginner with ARM architecture, i would like know if my idea is in the good way: 1: My arm flash memory is 512K 2: My picture is about 50K (8bits resolution) I want use an other part of this memory (flash) like frame buffer because i want add some caracteres on my picture. So I need to send on my display this buffer. I uses DMA (or FSMC) acces to send at my display a bus 16 bits width. This bus contain 16 bits to make a full pixel. I makes it for all pixels of my picture. In fact i uses my display like a (false) memory ... Do you think is possible ? ?