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Original question:

Does LCD Controller of AM335X supports 8-bit DMA transfer in LIDD mode?

AM3352: 8-bit DMA transfer in LIDD mode

Tony Tang
Mastermind 29222 points
Part Number: AM3352

Customer asks a same question as this post, as the old post did not get resolved, so I ask again.

https://e2e.ti.com/support/processors-group/processors/f/processors-forum/224097/does-lcd-controller-of-am335x-supports-8-bit-dma-transfer-in-lidd-mode/881794

When use LIDD in 8bit data bus mode, use DMA to serve LIDD between register and frame buffer, LIDD bus is 16bit, so application need prepare 8bit data in frame buffer in 16bit? 

  • 0
    TI__Guru* 87370 points

    The data width is determined by the LIDD_CTRL[2:0] bits which describe the type of panel you are connecting (see table 13-6 in the TRM).  There is a 8-bit type available, but you should also be able to work with in a 16-bit mode and adjust the data as you say (only putting the 8-bits of data in the LSBs, and ignore the upper byte)

    Regards,

    James

  • 0 in reply to JJD
    TI__Mastermind 29222 points
    JJD said:
    There is a 8-bit type available, but you should also be able to work with in a 16-bit mode

    Is it must or should be able to? if use DMA to serve LIDD, must put the 8bit data in LSB of 16bit data in buffer? or can we put 8-bit data one by one in buffer?

  • 0 in reply to Tony Tang
    TI__Guru* 87370 points

    I think you can work with 8-bit data, but then you have to set the LIDD_CTRL[2:0] to 8-bits mode.  Not sure if you panel will work in that mode.  If not, you have to change to 16-bit mode and put the 8-bit data into a 16-bit value with dummy bits in the upper byte.  

    Regards,

    James