TM4C1294 launchpad and Ethernet EMAC_INT_TRANSMIT interrupt source

I routinely get a EMAC_TX_NO_BUFFER interrupt after calling EMACTxDMAPollDemand. Is that expected? I cannot find any documentation on that interrupt as to what exactly it is signaling. It sounds like an error.

The descriptor's DES0_TX_CTRL_OWN bit is also not being cleared by hardware indicating a successful transmission.

Hello Jeff,

Are you developing a new ethernet stack?

Regards
Amit

Hi Amit,

Absolutely not. I am trying to tie into as much useful code as I can. I am running FreeRTOS. I need tcp sockets so I am attempting to port over the FreeRTOS TCP/ip stack. They have posted this porting guide:

www.freertos.org/.../Embedded_Ethernet_Porting.html

I am attempting to write the xNetworkInterfaceOutput() function. I have tried both a zero copy and full copy approach. I can't seem to setup my ethernet descriptors correctly.

I used a lot of the setup from the enet_uip example. Plugging in the buffer, and data length passed down from the FreeRTOS stack. Nothing I have tried seems to want to let me transmit.

This is what I have so far: I have tried both the copy and pointer route to no avail. 

BaseType_t xNetworkInterfaceOutput( xNetworkBufferDescriptor_t * const pxDescriptor, BaseType_t bReleaseAfterSend )
{
BaseType_t xReturn = pdPASS;
UINT32 i = 0;

//
// Wait for the previous packet to be transmitted.
//
while(TxDescriptor[currentTxDescriptor].ui32CtrlStatus &
DES0_TX_CTRL_OWN)
{
//
// Spin and waste time.
//
}

currentTxDescriptor++;

if(currentTxDescriptor >= NUMBER_TX_DESCRIPTORS){
currentTxDescriptor = 0;
}

// for(i=0;i<pxDescriptor->xDataLength;i++){
// TxBuffer[i] = *(pxDescriptor->pucEthernetBuffer + i);
// }

//memcpy((void *)TxBuffer, pxDescriptor->pucEthernetBuffer, pxDescriptor->xDataLength);

//
// Fill in the packet size and tell the transmitter to start work.
//
TxDescriptor[currentTxDescriptor].ui32Count = (uint32_t)pxDescriptor->xDataLength;
TxDescriptor[currentTxDescriptor].pvBuffer1 = pxDescriptor->pucEthernetBuffer;
//TxDescriptor[currentTxDescriptor].pvBuffer1 = TxBuffer;

TxDescriptor[currentTxDescriptor].ui32CtrlStatus =
(DES0_TX_CTRL_LAST_SEG | DES0_TX_CTRL_FIRST_SEG |
DES0_TX_CTRL_INTERRUPT | DES0_TX_CTRL_IP_ALL_CKHSUMS |
DES0_TX_CTRL_CHAINED | DES0_TX_CTRL_OWN);

//
// Tell the DMA to reacquire the descriptor now that we've filled it in.
//

MAP_EMACTxDMAPollDemand(EMAC0_BASE);
// EMACTxDMAPollDemand(EMAC0_BASE);    //try non rom version
while(xSemaphoreTake(TX_InterruptSem, (TickType_t) 5))     //portMAX_DELAY))
{

} //spin until the interrupt has signaled transmission was good

if(bReleaseAfterSend != pdFALSE){
pxDescriptor->pucEthernetBuffer = NULL;
vReleaseNetworkBufferAndDescriptor( pxDescriptor );
}

return xReturn;
}

Hello Jeff

I have assigned your forum post to our Ethernet expert

Regards
Amit

Hi Amit,

Thank you. Will they be reaching out to me on here or via email? Is there anything else they are going to need to diagnose my technical issue?

Thanks

Hello Jeff,

Are you referring to the lwIP port for TM4C129 MCU, inside TivaWare? The following files should be relevant to initializing and setting up the Transmit and Receive functions:

• "./utils/lwiplib.c",
• "./utils/lwiplib.h",
• "./third_party/lwip-1.4.1/ports/tiva-tm4c129/netif/tiva-tm4c129.c"

The hardware initialization is done in the functions:

• "lwIPInit" (in lwiplib.c) and
• "tivaif_hwinit" (in tiva-tm4c129.c).

The interrupt handler is called "tivaif_interrupt" (in file tiva-tm4c129.c).

Also, when posting code on the forum please use "Use rich formatting" and then click on the Syntaxhighlighter (with the icon ) . This makes the code easier to read and review, which results in faster response.

Thanks,

Sai

Hi Sai,

I am attempting to move away from the lwip. I need tcp socket support which I was told in another post is not supported in the lwip port for the tiva products. Because of that, I want to use the ip stack from freertos, which does have socket support.

My limited understanding of ethernet is that I the hardware interface level should be fairly uniform across the various offerings. The projects like the lwip and enet_uip should setup and interface to the mac and phy on the tiva chip fairly similarly. The layer I am attempting to write is passing buffers, it doesn't care what it says. That't left to higher level software, I believe. Maybe I am completely off my rocker, this is all very new to me.

I will look at those files. I am not familiar with them. I expect they should be similar to the enet_uip project I ported most of the code from.

Hello Jeff,

"enet_uip" is an application that uses lwIP. So underlying, it uses the files I mentioned. Although it does not hurt, you don't have to look at "enet_uip" for porting to a new TCP/IP stack, the files I mentioned should give a good idea of what is required to be set-up the hardware and how to transmit and receive packets.

Thanks,
Sai