Tiva Ethernet speed/data rate problems.

Hi,

My application involves implimenting a couple control systems using a couple TIVA micro-controllers being commanded by a main micro-controller over an Ethernet bus.  Telemetry data and other various commands will also be sent around on the Ethernet bus all using UDP.  I have modified the lwip example to send udp packets to a static IP. (my computer at the moment) and am only transmitting from within the lwip timer interrupt loop. In order to simulate me sending data whenever I want and not just when the loop runs I am calling the timer interrupt method from within my main. This makes sure that lwip doesnt crash over a long time because I am calling the send from a place that is not within the loop. 

The problem I have reached though is no matter what values I change I cant get the micro controller to send more than 100 packets a second (each one containing around 100 bytes). For my application to work I need that rate to be at least 100 times what it is now. 

The data sheet for the TM4C1294NCPDT micro controller which I plan on using for all the nodes of this system says it can do 10/100 Ethernet or at least it says its Mac and Phy can so it can. 

My question is, Is there something wrong with my code or some value I forgot to modify thats limiting my write speed or can the microcontroller just not handle that much communication at once or is the problem with LWIP and I should look into the third party industrial Ethernet stacks instead? 

I am getting the 100 packets a second number by inspecting the communication over wireshark and a custom python program both gave me the same results. 

My code has been copied and pasted below. 

//*****************************************************************************
//
// enet_lwip.c - Sample WebServer Application using lwIP.
//
// Copyright (c) 2013-2014 Texas Instruments Incorporated.  All rights reserved.
// Software License Agreement
// 
// Texas Instruments (TI) is supplying this software for use solely and
// exclusively on TI's microcontroller products. The software is owned by
// TI and/or its suppliers, and is protected under applicable copyright
// laws. You may not combine this software with "viral" open-source
// software in order to form a larger program.
// 
// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS.
// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT
// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY
// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL
// DAMAGES, FOR ANY REASON WHATSOEVER.
// 
// This is part of revision 2.1.0.12573 of the EK-TM4C1294XL Firmware Package.
//
//*****************************************************************************

#include <stdbool.h>
#include <stdint.h>
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "driverlib/flash.h"
#include "driverlib/interrupt.h"
#include "driverlib/gpio.h"
#include "driverlib/rom_map.h"
#include "driverlib/sysctl.h"
#include "driverlib/systick.h"
#include "utils/locator.h"
#include "utils/lwiplib.h"
#include "utils/ustdlib.h"
#include "utils/uartstdio.h"
#include "httpserver_raw/httpd.h"
#include "drivers/pinout.h"

//*****************************************************************************
//
//! \addtogroup example_list
//! <h1>Ethernet with lwIP (enet_lwip)</h1>
//!
//! This example application demonstrates the operation of the Tiva
//! Ethernet controller using the lwIP TCP/IP Stack.  DHCP is used to obtain
//! an Ethernet address.  If DHCP times out without obtaining an address,
//! AutoIP will be used to obtain a link-local address.  The address that is
//! selected will be shown on the UART.
//!
//! UART0, connected to the ICDI virtual COM port and running at 115,200,
//! 8-N-1, is used to display messages from this application. Use the
//! following command to re-build the any file system files that change.
//!
//!     ../../../../tools/bin/makefsfile -i fs -o enet_fsdata.h -r -h -q
//!
//! For additional details on lwIP, refer to the lwIP web page at:
//! savannah.nongnu.org/.../lwip
//
//*****************************************************************************

//*****************************************************************************
//
// Defines for setting up the system clock.
//
//*****************************************************************************
#define SYSTICKHZ               100
#define SYSTICKMS               (1000 / SYSTICKHZ)

//*****************************************************************************
//
// Interrupt priority definitions.  The top 3 bits of these values are
// significant with lower values indicating higher priority interrupts.
//
//*****************************************************************************
#define SYSTICK_INT_PRIORITY    0x80
#define ETHERNET_INT_PRIORITY   0xC0


//#define USE_DHCP                 0
//
//#define STATIC_IP_ADDRESS            	  0xC0A85A96  /* 192.168.90.150 */
//#define STATIC_NETMASK                    0xFFFFFF00  /* 255.255.255.0 */
//#define STATIC_GATEWAY                    0xC0A85AFE  /* 192.168.90.254 */



//*****************************************************************************
//
// The current IP address.
//
//*****************************************************************************
uint32_t g_ui32IPAddress;

//*****************************************************************************
//
// The system clock frequency.
//
//*****************************************************************************
uint32_t g_ui32SysClock;


struct udp_pcb *remote_pcb;
struct pbuf* pbuf1;
char buf [120];

static int n = 0;

//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, uint32_t ui32Line)
{
}
#endif

//*****************************************************************************
//
// Display an lwIP type IP Address.
//
//*****************************************************************************
void
DisplayIPAddress(uint32_t ui32Addr)
{
    char pcBuf[16];

    //
    // Convert the IP Address into a string.
    //
    usprintf(pcBuf, "%d.%d.%d.%d", ui32Addr & 0xff, (ui32Addr >> 8) & 0xff,
            (ui32Addr >> 16) & 0xff, (ui32Addr >> 24) & 0xff);

    //
    // Display the string.
    //
    UARTprintf(pcBuf);
}

//*****************************************************************************
//
// Required by lwIP library to support any host-related timer functions.
//
//*****************************************************************************
void
lwIPHostTimerHandler(void)
{
    uint32_t ui32Idx, ui32NewIPAddress;

    //
    // Get the current IP address.
    //
    ui32NewIPAddress = lwIPLocalIPAddrGet();

    //
    // See if the IP address has changed.
    //
    if(ui32NewIPAddress != g_ui32IPAddress)
    {
        //
        // See if there is an IP address assigned.
        //
        if(ui32NewIPAddress == 0xffffffff)
        {
            //
            // Indicate that there is no link.
            //
            UARTprintf("Waiting for link.\n");
        }
        else if(ui32NewIPAddress == 0)
        {
            //
            // There is no IP address, so indicate that the DHCP process is
            // running.
            //
            UARTprintf("Waiting for IP address.\n");
        }
        else
        {
            //
            // Display the new IP address.
            //
            UARTprintf("IP Address: ");
            DisplayIPAddress(ui32NewIPAddress);
            UARTprintf("\nOpen a browser and enter the IP address.\n");
        }

        //
        // Save the new IP address.
        //
        g_ui32IPAddress = ui32NewIPAddress;

        //
        // Turn GPIO off.
        //
        MAP_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_1, ~GPIO_PIN_1);
    }

    //
    // If there is not an IP address.
    //
    if((ui32NewIPAddress == 0) || (ui32NewIPAddress == 0xffffffff))
    {
        //
        // Loop through the LED animation.
        //
    	UARTprintf("no ip address");
        for(ui32Idx = 1; ui32Idx < 17; ui32Idx++)
        {

            //
            // Toggle the GPIO
            //
            MAP_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_1,
                    (MAP_GPIOPinRead(GPIO_PORTN_BASE, GPIO_PIN_1) ^
                     GPIO_PIN_1));

            SysCtlDelay(g_ui32SysClock/(ui32Idx << 1));
        }
    } else {

    	UARTprintf("I have an IP");

        //
        // Transmit to UDP
        //

    	//static int n = 0;

    	pbuf1 = pbuf_alloc(PBUF_TRANSPORT, 100, PBUF_RAM);
        pbuf1->payload = (void*)buf;
        pbuf1->tot_len = 15;
        pbuf1->len = 15;

        n++;

        //buf[0] = 0x10;
        buf[0] = n;
        buf[1] = n-1;

        //buf[1] = 0;

        if(n>= 55){
        	n=0;
        }

        //usprintf(&buf[4], " test %d", n++);
        //udp_send(remote_pcb, pbuf1);
        //pbuf_free(pbuf1);

        //udp_send(mypcb, pbuf1);  //this works


        struct ip_addr udpDestIpAddr;
        IP4_ADDR(&udpDestIpAddr, 192, 168, 7, 1);
        udp_sendto(remote_pcb, pbuf1, &udpDestIpAddr, 1234); // this does not work

        pbuf_free(pbuf1);

    }


}

//*****************************************************************************
//
// The interrupt handler for the SysTick interrupt.
//
//*****************************************************************************
void
SysTickIntHandler(void)
{
    //
    // Call the lwIP timer handler.
    //
    lwIPTimer(SYSTICKMS);
}

//*****************************************************************************
//
// This example demonstrates the use of the Ethernet Controller.
//
//*****************************************************************************
int
main(void)
{
    uint32_t ui32User0, ui32User1;
    uint8_t pui8MACArray[8];

    //
    // Make sure the main oscillator is enabled because this is required by
    // the PHY.  The system must have a 25MHz crystal attached to the OSC
    // pins. The SYSCTL_MOSC_HIGHFREQ parameter is used when the crystal
    // frequency is 10MHz or higher.
    //
    SysCtlMOSCConfigSet(SYSCTL_MOSC_HIGHFREQ);

    //
    // Run from the PLL at 120 MHz.
    //
    g_ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
                                             SYSCTL_OSC_MAIN |
                                             SYSCTL_USE_PLL |
                                             SYSCTL_CFG_VCO_480), 120000000);

    //
    // Configure the device pins.
    //
    PinoutSet(true, false);

    //
    // Configure UART.
    //
    UARTStdioConfig(0, 115200, g_ui32SysClock);

    //
    // Clear the terminal and print banner.
    //
    UARTprintf("\033[2J\033[H");
    UARTprintf("Ethernet lwIP example\n\n");

    //
    // Configure Port N1 for as an output for the animation LED.
    //
    MAP_GPIOPinTypeGPIOOutput(GPIO_PORTN_BASE, GPIO_PIN_1);

    //
    // Initialize LED to OFF (0)
    //
    MAP_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_1, ~GPIO_PIN_1);

    //
    // Configure SysTick for a periodic interrupt.
    //
    MAP_SysTickPeriodSet(g_ui32SysClock / SYSTICKHZ);
    MAP_SysTickEnable();
    MAP_SysTickIntEnable();

    //
    // Configure the hardware MAC address for Ethernet Controller filtering of
    // incoming packets.  The MAC address will be stored in the non-volatile
    // USER0 and USER1 registers.
    //
    MAP_FlashUserGet(&ui32User0, &ui32User1);
    if((ui32User0 == 0xffffffff) || (ui32User1 == 0xffffffff))
    {
        //
        // We should never get here.  This is an error if the MAC address has
        // not been programmed into the device.  Exit the program.
        // Let the user know there is no MAC address
        //
        UARTprintf("No MAC programmed!\n");
        while(1)
        {
        }
    }

    //
    // Tell the user what we are doing just now.
    //
    UARTprintf("Waiting for IP.\n");

    //
    // Convert the 24/24 split MAC address from NV ram into a 32/16 split MAC
    // address needed to program the hardware registers, then program the MAC
    // address into the Ethernet Controller registers.
    //
    pui8MACArray[0] = ((ui32User0 >>  0) & 0xff);
    pui8MACArray[1] = ((ui32User0 >>  8) & 0xff);
    pui8MACArray[2] = ((ui32User0 >> 16) & 0xff);
    pui8MACArray[3] = ((ui32User1 >>  0) & 0xff);
    pui8MACArray[4] = ((ui32User1 >>  8) & 0xff);
    pui8MACArray[5] = ((ui32User1 >> 16) & 0xff);

    //
    // Initialize the lwIP library, using DHCP.
    //
    //lwIPInit(g_ui32SysClock, pui8MACArray, 0, 0, 0, IPADDR_USE_DHCP);


    //IP address - 192.168.7.2 = 0xC0A80702 // own device IP address
    //Gateway - 192.168.7.1 = 0xC0A80701
    //subnet mask - 255.255.255.0 = 0xFFFFFF00

    lwIPInit(g_ui32SysClock, pui8MACArray, 0xC0A80702, 0xFFFFFF00, 0xC0A80701, IPADDR_USE_STATIC);
    //lwIPInit(pucMACAddr, DEFAULT_IPADDR, DEFAULT_NET_MASK, DEFAULT_GATEWAY_ADDR, IPADDR_USE_STATIC);


    //
    // Setup the device locator service.
    //
    LocatorInit();
    LocatorMACAddrSet(pui8MACArray);
    LocatorAppTitleSet("EK-TM4C1294XL enet_io");

    //
    // Initialize a sample httpd server.
    //
    httpd_init();


    udp_init();

    struct udp_pcb * mypcb;
    mypcb = udp_new();
    if (mypcb == NULL)
    {
        UARTprintf("udp failed.\n");
    }
    else
    {
        UARTprintf("udp up.\n");
    }

    if (udp_bind(mypcb, IP_ADDR_ANY, 8760) != ERR_OK)
    {
        UARTprintf("udp bind failed.\n");
    }



    //
    // Set the interrupt priorities.  We set the SysTick interrupt to a higher
    // priority than the Ethernet interrupt to ensure that the file system
    // tick is processed if SysTick occurs while the Ethernet handler is being
    // processed.  This is very likely since all the TCP/IP and HTTP work is
    // done in the context of the Ethernet interrupt.
    //
    MAP_IntPrioritySet(INT_EMAC0, ETHERNET_INT_PRIORITY);
    MAP_IntPrioritySet(FAULT_SYSTICK, SYSTICK_INT_PRIORITY);

    //
    // Loop forever.  All the work is done in interrupt handlers.
    //

    int loopCount = 0;

    while(1)
    {

    	uint32_t ui32Idx, ui32NewIPAddress;

//    	loopCount++;


        // Get the current IP address.
        //

        ui32NewIPAddress = lwIPLocalIPAddrGet();

        //UARTprintf("IP Address: ");
        //DisplayIPAddress(ui32NewIPAddress);


        if(loopCount%200 == 0){
        	lwIPHostTimerHandler();
        }

        if(loopCount >= 250){
        	loopCount = 0;
        }





    }
}