TI RTOS Ethernet DMA example

Hi Saleem,
We don't have any such example or driver for TI-RTOS.
Best regards,
Janet

Hi Janet,

Is the NDK is handling all the TCP/IP protocol? and it not using DMA for data tranfer. Is it correct?

Is there any way to add DMA for data transfer?

Thanks.

Hi Saleem,
It turns out that I was misinformed about the NDK for Tiva, and the driver actually does use the DMA! You can find the driver in your TI-RTOS installation, under products/tidrivers-tivac_2_xx_xx_xx/packages/ti/drivers/emac/EMACSnow.c
I hope this is what you were looking for.
Best regards,
Janet

HI Janet,

I have found the EMACSnow file. I am bit confused. TIRTOS user guide says:

The EMAC driver is designed to be used by the NDK. The only function that must be called is the
EMAC_init() function. This function must be called before BIOS_start() is called to ensure that the driver
is initialized before the NDK starts.

But the EMAC_init funciton is not in EMACSnow file. Does the EMAC_init function in file "EMAC.h" initialzes the DMA?

Does the DMA is used by default for data transfer? OR we need to explicitly call the function "EMACSnow_InitDMADescriptors" to initialize DMA and data transfer.

Please advice.

Thanks.

Hi Saleem,

EMAC_init() will call EMACSnow_init().  You shouldn't need to call EMACSnow_initDMADescriptors.  There is table in your board file that is used by the NDK:

/*
 *  Required by the Networking Stack (NDK). This array must be NULL terminated.
 *  This can be removed if NDK is not used.
 *  Double curly braces are needed to avoid GCC bug #944572
 *  bugs.launchpad.net/.../944572
 */
NIMU_DEVICE_TABLE_ENTRY NIMUDeviceTable[2] = {
    {
#if TI_EXAMPLES_PPP
        /* Use PPP driver for PPP example only */
        .init = USBSerialPPP_NIMUInit
#else
        /* Default: use Ethernet driver */
        .init = EMACSnow_NIMUInit
#endif
    },
    {NULL}
};

This is how the NDK will call EMACSnow_NIMUInit(), wihch initializes the DMA descriptors.

Best regards,

Janet

Hi Janet,

Thank you. So by default data transfer over ethernet is done using after DMA EMAC_init() . Is it correct?

Thanks.

Hi Saleem,

Yes, it uses DMA.  There are Tx and Rx descriptors that are chained up to the peripheral.

Best regards,

Janet

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