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Regarding general-purpose memory controller (GPMC)

Hi,

We have a Netra hardware where the GPMC is connected to a FIFO external memory of 512 byte and is clocked at 27 Mhz.

Here we are required to transfer the data to the external memory  (address : 0x9000000) through GPMC.

i have to following doubts,

1. Whether we can use EDMA for a byte by byte transfer.

2. Any mechanism to transfer data at a block level.

3. ideally how much data we can transfer through GPMC /Sec.

Regards,

Sudeep

  • Hi Sudeep,

    Sudeep Hegde said:
    1. Whether we can use EDMA for a byte by byte transfer.

    I think you can. You can configure the GPMC FIFO threshold to 1 byte: GPMC_PREFETCH_CONFIG1[14:8] FIFOTHRESHOLD = 0x1 (1 byte) - this bit field selects the maximum number of bytes read from the GPMC FIFO or written to the GPMC FIFO by the host on a DMA request. Also you can configure this on the EDMA side, in EDMA Destination FIFO Options Register DFOPTn[10:8] FWID = 0x0 (FIFO width is 8-bit)

    Sudeep Hegde said:
    2. Any mechanism to transfer data at a block level.

    If by "transfer data at a block level" you mean that you need to transfer the data in bigger than 1 byte blocks, yes you can. Check DM816x TRM, chapter 5 EDMA:

    5.2.3.2.4 Count for 1st Dimension (ACNT)

    5.2.3.2.5 Count for 2nd Dimension (BCNT)

    5.2.3.2.6 Count for 3rd Dimension (CCNT)

    5.2.3.9 Element Size

    5.3.1 Block Move Example

    Sudeep Hegde said:
    3. ideally how much data we can transfer through GPMC /Sec.

    Check DM816x datasheet, 8.8.2 GPMC Electrical Data and Timing; DM816x TRM, 9.3.6 GPMC Timing Parameters

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/717/p/99986/373493.aspx#373493

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/t/196291.aspx

    http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/185451/669891.aspx

    BR

    Pavel

  • Thanks Pavel for your valuable input, we will explore on the EDMA option.

    Please can you provide some pointers related to  EDMA FIFO transfer.

    Regards,

    Sudeep

  • Hi Sudeep,

    You can check our EDMA driver user guide with the EDMA sample test application:

    http://processors.wiki.ti.com/index.php/TI81XX_PSP_EDMA_Driver_User_Guide

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

    Check also DM816x TRM

    5.3 EDMA Transfer Examples

    5.3.4 Peripheral Servicing Example  (GPMC is peripheral)

    BR

    Pavel