TM4C1294NCPDT: How many LWIP UDP connection is allowed ?

Hello Ping,

It looks like this limitation comes from the default declaration of UDP control blocks. This is defined inside of the following file located in TivaWare: [Install Path]/third_party/lwip-1.4.1/src/include/lwip/opt.h. From my understanding, this value can be modified in the "lwipopts.h" file of the project to expand the capability at a project specific level.

/**
 * MEMP_NUM_UDP_PCB: the number of UDP protocol control blocks. One
 * per active UDP "connection".
 * (requires the LWIP_UDP option)
 */
#ifndef MEMP_NUM_UDP_PCB
#define MEMP_NUM_UDP_PCB                4
#endif

Check your lwipopts.h file, around line 95, for #define MEM_NUM_UDP_PCB.

It defaults to 4. Change it as needed.

//*****************************************************************************
//
// ---------- Internal Memory Pool Sizes ----------
//
//*****************************************************************************
#define MEMP_NUM_PBUF                     48    // Default 16
//#define MEMP_NUM_RAW_PCB                4
//#define MEMP_NUM_UDP_PCB                4     // THIS ONE!
#define MEMP_NUM_TCP_PCB                  16    // Default 5
//#define MEMP_NUM_TCP_PCB_LISTEN         8
#define MEMP_NUM_TCP_SEG                  32  // Default 16
//#define MEMP_NUM_REASSDATA              5
//#define MEMP_NUM_ARP_QUEUE              30
//#define MEMP_NUM_IGMP_GROUP             8
#define MEMP_NUM_SYS_TIMEOUT              8
//#define MEMP_NUM_NETBUF                 2
//#define MEMP_NUM_NETCONN                4
//#define MEMP_NUM_TCPIP_MSG_API          8
//#define MEMP_NUM_TCPIP_MSG_INPKT        8
#define PBUF_POOL_SIZE                    48    // Default 16