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GPMC interface to Nand flash and LCM display

Steven Weng1
Expert 2200 points

Hi All,

Sorry I am new to GPMC interface.

The GPMC_D0 ~ GPMC_D7 pins are connected to the data pin of nand flash and LCM display(character LCM) on our board.

Is it possible to read/write nand flash and control LCM at the same time?

Does it conflict?

Thanks.

BR

Steven

  • 0
    TI__Guru**** 170625 points

    Steven,

     In DM816x TI EVM, all GPMC data signal (GPMC_D0 to GPMC_D15) are connected to two things:

    1. 16-bit NAND flash chip

    2. GPMC expansion connector J19 -> 16-bit NOR flash chip

    As these two flash chips are using the same GPMC chip select (CS0), these are mutually exclusive and can not be used at the same time.

    Steven Weng1 said:

    The GPMC_D0 ~ GPMC_D7 pins are connected to the data pin of nand flash and LCM display(character LCM) on our board.

    Is it possible to read/write nand flash and control LCM at the same time?

    Does it conflict?

    You can try with using different chip select signals (i.e. GPMC_CS0 for NAND and GPMC_CS1 for display), but I am not sure if this will work for you.

    Other option you can try is using GPMC_D[0-7] for 8-bit NAND flash chip and GPMC_D[8:15] for display.

    Note that in DM814x TI EVM, where we have LCD display connected to the DM814x processor, this LCD display has nothing common with GPMC, but connected to VOUT0 (digital video output signals).

    Regards,
    Pavel

  • 0 in reply to Pavel Botev
    Expert 2200 points

    Hi Pavel,

    Thank for your quick reply.

    The following is our hardware setting:

    Nand flash -  

    Use GPMC_CS0,

    GPMC_D[0-7] connected to nand flash data pins

    Character LCM display -

    Use GPMC_CS3,

    GPMC_D[0-7] connected to LCM data pins,

    GPMC_A[0-1] connected to LCM control pins

    I am concerned about the GPMC_D[0-7] are mutually exclusive.

    Our LCM display is a simple character dot matrix display that use intel 8080 8-bits interface. The refresh rate is very low. Is GPMC interface suitable for this case? 

    BR,

    Steven

  • 0 in reply to Steven Weng1
    TI__Guru**** 170625 points

    Steven,

    It depends very much an what type of LCD you want to connect.

    Small LCDs (< 3") typically use an MPU type interface so could use either GPIO or the GPMC interface.

    Medium LCDs (3" to 7") often use parallel CMOS raster interfaces so should be connected to the DVO outputs.

    larger LCDs (7" and above) often use an LVDS interface so will need a serializer such as TIs LVDS83B connected to the DVO port.

    You can look at the following Wiki page which was written for OMAP2/3 but is applicable here too.

    http://processors.wiki.ti.com/index.php/LCD_connectivity

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/100/t/67996.aspx

    Regards,
    Pavel

  • 0 in reply to Pavel Botev
    Expert 2200 points

    Pavel,

    Very thanks for the detailed reply.It's very useful for me.

    Our LCD use an MPU type interface(Parallel interface with three control pins and 8-bits data pins)

    Now LCD's control pins connected to GPMC address pins and data pins connected to GPMC data pins.

    I was wondering how GPMC address pins control the LCD's control pins? It seems another GPIO pins will be good.

    Anyway, I will look into GPMC interface. Thanks again.

    BR,

    Steven