MSP-EXP432E401Y: MSP-EXP432E401Y

 In enet_lwip.c file I added UdpEchoRecv, UdpEchoInit and udp_send_data function but still I am unable to see udp packet from MCU to my PC on wireshark too.

I am attaching enet_lwip.c file. Please tell what else modification is required.

//*****************************************************************************
//
// enet_lwip.c - Sample WebServer Application using lwIP.
//
// Copyright (c) 2013-2017 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.
//
//
//*****************************************************************************

#include <stdbool.h>
#include <stdint.h>
#include "ti/devices/msp432e4/driverlib/driverlib.h"
#include "ti/devices/msp432e4/inc/msp.h"
#include "ustdlib.h"
#include "uartstdio.h"
#include "pinout.h"
#include "locator.h"
#include "lwiplib.h"
#include "lwip/apps/httpd.h"

//*****************************************************************************
//
//! \addtogroup example_list
//! <h1>Ethernet with lwIP (enet_lwip)</h1>
//!
//! This example application demonstrates the operation of the MSP432E4
//! 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/examples/makefsfile/makefsfile.exe -i fs -o enet_fsdata.h -r -h -q
//!
//! For additional details on lwIP, refer to the lwIP web page at:
//! http://savannah.nongnu.org/projects/lwip/
//
//*****************************************************************************

//*****************************************************************************
//
// Defines for setting up the system clock.
//
//*****************************************************************************

struct udp_pcb *pcb;  // Assume this is properly initialized and configured
struct pbuf *p;
#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 PORT                     23

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

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

//*****************************************************************************
//
// Volatile global flag to manage LED blinking, since it is used in interrupt
// and main application.  The LED blinks at the rate of SYSTICKHZ.
//
//*****************************************************************************
volatile bool g_bLED;

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



void udp_send_data(struct udp_pcb *pcb, const char *data, size_t len) {
    // Create a packet buffer and fill it with data
    struct pbuf *p = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
    if (!p) {
        UARTprintf("Error allocating pbuf\n");
        return;
    }
    // Copy data into the packet buffer
    pbuf_take(p, data, len);

    // Send data using udp_send
    err_t err = udp_send(pcb, p);
    if (err != ERR_OK) {
        UARTprintf("Error sending UDP packet\n");
        return;
    }

    // Free the packet buffer
    pbuf_free(p);
}

void
UdpEchoRecv(void *arg, struct udp_pcb *pcb, struct pbuf *p, struct
            ip_addr *addr, u16_t port)
{
    if (p != NULL) {
        //
        // Send received packet back to sender. The udp_sendto is similar to
        // udp_send(), but sends to any remote address.
        //
        udp_sendto(pcb, p, addr, port);

        //
        // Free the pbuf.
        //
        pbuf_free(p);
    }
}


void
UdpEchoInit(void)
{
   // struct udp_pcb * pcb;

    //
    // Get the new PCB.
    //
    pcb = udp_new();
    if (pcb == NULL) {
        UARTprintf("udp_new failed!\n");
        return;
    }

    //
    // Bind to any IP address on port 23.
    //
    if (udp_bind(pcb, IP_ADDR_ANY, PORT) != ERR_OK) {
        UARTprintf("udp_bind failed!\n");
        return;
    }

    //
    // Register UdpEchoRecv() as callback function for received packets.
    //
    udp_recv(pcb, UdpEchoRecv, NULL);
}




//*****************************************************************************
//
// 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 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;
    }

    //
    // If there is not an IP address.
    //
    if((ui32NewIPAddress == 0) || (ui32NewIPAddress == 0xffffffff))
    {
        //
        // Do nothing and keep waiting.
        //
    }
}

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

    //
    // Tell the application to change the state of the LED (in other words
    // blink).
    //
    g_bLED = true;
}

//*****************************************************************************
//
// 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);
    lwIPInit(g_ui32SysClock, pui8MACArray, 3232235777, 4294967040, 0, IPADDR_USE_STATIC);
    UdpEchoInit();

    const char *message = "Hello, World!";
   udp_send_data(pcb, message, 11);

    //
    // Setup the device locator service.
    //
    LocatorInit();
    LocatorMACAddrSet(pui8MACArray);
    LocatorAppTitleSet("MSP432E4 enet_io");

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

    //
    // 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, processing the LED blinking.  All the work is done in
    // interrupt handlers.
    //
    while(1)
    {
        //
        // Wait till the SysTick Interrupt indicates to change the state of the
        // LED.
        //
        while(g_bLED == false)
        {
        }

        //
        // Clear the flag.
        //
        g_bLED = false;

        //
        // Toggle the LED.
        //
        MAP_GPIOPinWrite(GPIO_PORTN_BASE, GPIO_PIN_1,
                         (MAP_GPIOPinRead(GPIO_PORTN_BASE, GPIO_PIN_1) ^
                          GPIO_PIN_1));
    }
}

I just replied to your other thread. If you want to continue on this thread, then please do not ask the same questions on multiple threads. In the  other thread, I ask the below questions for clarification. 

  - What tool do you use to send udp data to the MCU? I normally use Hercules. https://www.hw-group.com/software/hercules-setup-utility. The UdpEchoRecv is a callback that is called when the Echo Server receives data. Upon receiving data, it simply echoes back to the sender (the client application running on the PC). Do you have data that is sent from the PC? What does it show?

  - Is your client on the same subnet as the server?

  - What is the result if you use DHCP?