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C6748 LCDK LCD with L2 RAM

Hi,

I am using C6748 LCDK with a daughter board with 320x240 TFT LCD. Since the final custom board designed by us does not have DDR2, I am trying to put all the code to L2 RAM.

As part of this experiment, I modified the pdk_C6748_2_0_0_0\C6748_StarterWare_1_20_03_03\examples\lcdkC6748\raster\rasterDisplay.c for the LCD size 320x240 and created an image for this size and it gets displayed when all sections of code is put to DDR2.

I have added L2 RAM in the .cmd file and all sections are relocated to L2 RAM and the image does not get displayed.

L1P: o = 0x11E00000 l = 0x00008000

L1D: o = 0x11F00000 l = 0x00008000
//L2 started after 16K
L2: o = 0x11804000 l = 0x0003C000
DDR2: o = 0xC0000000 l = 0x08000000

Found that when the image is defined as a 'const' section and if this alone is put in L2 RAM, the code just stops working. So it looks like there is some issue in when LCD controller DMA from L2RAM?

Any help is appreciated.

Regards,

Nandan

  • Hi Nandan

    This is unfortunate, as  on C6748 the LCD does not have access to internal DSP memories, it can only access DDR. 

    You will find this information conveyed in the datasheet via the memory map table , as well as the TRM system interconnect chapter , table 3-1. 

    You will need DDR if you need a functional LCD in your design.

    Regards

    Mukul

  • Thanks Mukul for the quick response.

    I just checked the system interconnect page and found that LCD can not access L2 RAM. It was not mentioned under LCDC section and also I was getting EOF interrupts !!

    Our hardware design is in progress, before that we wanted to prove the design.

    Our requirement is to have some simple text menus on the LCD, and CPU will have lot of cycles free to interface to LCD, is there any option available without using DDR?

    Regards,

    Nandan

  • If the LCD is simple enough and does not need high bandwidth etc, perhaps you can look at LCDs that can be driven/controlled for a serial interface like SPI on c6748 e.g. the ones mentioned here

    http://processors.wiki.ti.com/index.php/Getting_Started_with_the_TIVA%E2%84%A2_C_Series_TM4C123G_LaunchPad

    Hope this helps.
    Regards

    Mukul