Using touchgfx without external RAM

Hi,

Could you maybe share your CubeMX project or screenshots of your configuration (unless confidential)?

First just to check, you put the framebuffer in internal RAM but do you have enough RAM for it ? A framebuffer size is Height * Width * bpp. Depending on your configuration you might be using 2 framebuffers + annimation storage (so in total for that example, it is 3 framebuufers). And be careful as you also need some storage for the TouchGFX framezork and memory for the "heaviest" screen of your GUI.

The number of framebuffer you wish to use can be modified in CubeMX in the X-CUBE-TouchGFX configuraqtion in the framebuffer strategy config.If you already all this then sorry :grinning_face_with_sweat:.

What you can do as well is look at the H7B3 disco board. If i am not mistaken it also does not use external RAM, so have a look at its application template and CubeMX config.

/Romain

Out of curiosity, why do you put the start address at 0xC0000000 in the last screenshot? When I opened the ioc project you shared, it automatically sets it to 0x20020000. The configuration overall seems ok at first glance, I compared it to the F746G disco AT and the H7b3 disco AT we provide in Designer. The only thing that surprises me yeah is that you set the color frame buffer start address at 0x20010000 and then the start address for the "touchgfx" framebuffer at 0xc0000000

Could you test it real quick if that makes sense?

I'm also not 100% sure that those 320kbytes of internal RAM are really accessible, maybe only a portion of it is

For internal ram you cannot use direct address for framebuffer (maybe yes but then you need edit linker scripts...). Compiler need manage RAM and too framebuffer.

Then you need in code create array for it and use his pointer in config.

example

uint8_t framebuffer[480x272*2];

then change in ioc By Address to other settings...

And yes you need continuos RAM then here you is over limit , but still exist way to use some workarounds, as first you can dont use full screen and make some border on display, that reduce RAM needed. Example 400x200

Second way is use CLUT , but this isnt supported in TouchGFX, then you need make GUI...

Third as you say is use other framebuffer type, with one byte per pixel, Touch GFX support many options for it ... need manual config

I did as you instructed the 480*260 framebuffer size was Ok but the display showed nothing, should I do another things in addition to this partial frame buffer?

Hi @ETale.1​ 

May be it is now too late to post an answer

I was also looking to use Touchgfx without external RAM as my application has very minimal graphics. This post helped me a lot to poke at the right places

Here is what I did

• Open Cube MX configurator
• Change to single buffer and by allocation

• This would update TouchGFXGeneratedHAL.cpp as described in here Framebuffer Strategies | TouchGFX Documentation
• What they dont post is that there is another file TouchGFXHAL.cpp which is not generated and overrides whatever was changed in the base TouchGFXGeneratedHAL class
• So, we need to comment out the following two lines in the TouchGFXHAL.cpp file below

void TouchGFXHAL::initialize()
{
 // Calling parent implementation of initialize().
 //
 // To overwrite the generated implementation, omit call to parent function
 // and implemented needed functionality here.
 // Please note, HAL::initialize() must be called to initialize the framework.
 
 TouchGFXGeneratedHAL::initialize();
// Commented out
 // setFrameBufferStartAddresses((void*)0xC0000000, (void*)0xC003FC00, (void*)0xC007F800); //enable the animation storage to allow slide animations
 // lockDMAToFrontPorch(false);
 instrumentation.init();
 setMCUInstrumentation(&instrumentation);
 enableMCULoadCalculation(true);
}

• Now, you have to modify the linker files and create a section named 'TouchGFX_Framebuffer' which is the name used by the code generator
• Modify STM32F746NGHX_RAM.ld

MEMORY
{
 RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 64K
 // frame buffer is 255k long in my case
 RAM_FRAME_BUFFER (xrw) : ORIGIN = 0x20001000, LENGTH = 256K
 FLASH (rx) : ORIGIN = 0x8000000, LENGTH = 1024K
}
 
// add at the end
 /*Added for frame buffer */
 .TouchGFX_Framebuffer : {
 __TouchGFX_Framebuffer_start = .;
 KEEP(*(.TouchGFX_Framebuffer))
 __TouchGFX_Framebuffer_end = .;
 } > RAM_FRAME_BUFFER

• Clean and build

Thanks,

Vimal

I am interested as well to know this. Would choosing partial framebuffer help in this case?

https://support.touchgfx.com/docs/development/scenarios/lowering-memory-usage-with-partial-framebuffer