CCS/LAUNCHXL2-RM57L: Decrease time intervals to send and receive data using lwIP

Hi QJ Wang,

This is my working echo TCP example. Previously, I was printing the data at the terminal using the SCI port, to view the data that the RM57 launchpad was receiving and sending at the CCS terminal. I am using the sciDisplayText function in the code that I am working on to print this data in the terminal. However, when I removed the display of the data on the terminal through the SCI port, the latency decreased considerably. In the last tests that I have done, I have obtained time intervals less than 50 ms, so I think that the problem has been solved. But, I remain attentive to any other recommendation.

Thank you so much for your reply. 

Best regards.

// Source: initialization and control path for the lwIP and EMAC driver and can be called from system main
// Source echo_tcp_ip in: cvs.savannah.gnu.org/.../

#include "lwiplib.h"
#include "HL_sci.h"
#include "lwip\inet.h"
#include "locator.h"
#include "lwip/debug.h"
#include "lwip/stats.h"
#include "lwip/tcp.h"
#include<stdio.h>

#define sciREGx  sciREG1

uint8_t    txtCRLF[]         = {'\r', '\n'};
uint8_t    txtTitle[]        = {"WELCOME - LINK: CCL/TI "};
uint8_t    txtTI[]           = {"Texas Instruments"};
uint8_t    txtLittleEndian[] = {"Device Little Endian"};
uint8_t    txtEnetInit[]     = {"Ethernet (DHCP)"};
uint8_t    txtErrorInit[]    = {"-------- ERROR INICIALIZANDO HARDWARE --------"};
uint8_t    txtIPAddrTxt[]    = {"IPv4: "};
uint8_t    * txtIPAddrItoA;

volatile int countEMACCore0RxIsr = 0;
#pragma INTERRUPT(EMACCore0RxIsr, IRQ)

void EMACCore0RxIsr(void)
{
   countEMACCore0RxIsr++;
   lwIPRxIntHandler(0);
}

volatile int countEMACCore0TxIsr = 0;
#pragma INTERRUPT(EMACCore0TxIsr, IRQ)

void EMACCore0TxIsr(void)
{
 countEMACCore0TxIsr++;
   lwIPTxIntHandler(0);
}

void IntMasterIRQEnable(void)
{
 _enable_IRQ();
 return;
}

void IntMasterIRQDisable(void)
{
 _disable_IRQ();
 return;
}

unsigned int IntMasterStatusGet(void)
{
   return (0xC0 & _get_CPSR());
}

void sciDisplayText(sciBASE_t *sci, uint8_t *text,uint32_t length)
{
   while(length--)
   {
       while ((sci->FLR & 0x4) == 4);
       sciSendByte(sci,*text++);
   };
}

void sciNotification(sciBASE_t *sci, uint32_t flags)
{
    return;
}

void smallDelay(void) {
      static volatile unsigned int delayval;
      delayval = 10000;
      while(delayval--);
}

static struct tcp_pcb *ccl_pcb;

enum ccl_states
{
  ES_NONE = 0,
  ES_ACCEPTED,
  ES_RECEIVED,
  ES_CLOSING
};

struct ccl_state
{
  u8_t state;
  u8_t retries;
  struct tcp_pcb *pcb;
  struct pbuf *p;
};

err_t ccl_accept(void *arg, struct tcp_pcb *newpcb, err_t err);
err_t ccl_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err);
void ccl_error(void *arg, err_t err);
void ccl_close(struct tcp_pcb *tpcb, struct ccl_state *es);
void ccl_send(struct tcp_pcb *tpcb, struct ccl_state *es);

///////////////////////////////////////////////////////////////////////////
//                                                                       //
///////////////////////////////////////////////////////////////////////////

err_t ccl_accept(void *arg, struct tcp_pcb *newpcb, err_t err)
{
  err_t ret_err;
  struct ccl_state *es;
  LWIP_UNUSED_ARG(arg);
  LWIP_UNUSED_ARG(err);
  tcp_setprio(newpcb, TCP_PRIO_MIN);
  sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
  sciDisplayText(sciREGx, (uint8_t*)"PRIORITY", sizeof("PRIORITY"));
  sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
  es = (struct ccl_state *)mem_malloc(sizeof(struct ccl_state));
  if (es != NULL)
  {
    es->state = ES_ACCEPTED;
    es->pcb = newpcb;
    es->retries = 0;
    es->p = NULL;
    sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
    sciDisplayText(sciREGx, (uint8_t*)"ACCEPTED", sizeof("ACCEPTED"));
    sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
    tcp_arg(newpcb, es);
    tcp_recv(newpcb, ccl_recv);
    tcp_err(newpcb, ccl_error);
    ret_err = ERR_OK;
  }
  else
  {
    ret_err = ERR_MEM;
  }
  return ret_err;
}

err_t ccl_recv(void *arg, struct tcp_pcb *tpcb, struct pbuf *p, err_t err)
{
  struct ccl_state *es;
  err_t ret_err;
  LWIP_ASSERT("arg != NULL",arg != NULL);
  es = (struct ccl_state *)arg;
  if (p == NULL)
  {
    es->state = ES_CLOSING;
    if(es->p == NULL)
    {
       ccl_close(tpcb, es);
       sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
       sciDisplayText(sciREGx, (uint8_t*)"CLOSE", sizeof("CLOSE"));
       sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
    }
    else
    {
      ccl_send(tpcb, es);
    }
    ret_err = ERR_OK;
  }
  else if(err != ERR_OK)
  {
    if (p != NULL)
    {
        es->p = NULL;
        pbuf_free(p);
    }
    ret_err = err;
    sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
    sciDisplayText(sciREGx, (uint8_t*)"P ERROR", sizeof("P ERROR"));
    sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
  }

  else if(es->state == ES_ACCEPTED)
  {
    es->state = ES_RECEIVED;
    es->p = p;
    ccl_send(tpcb, es);
    ret_err = ERR_OK;
  }

  else if (es->state == ES_RECEIVED)
  {
    if(es->p == NULL)
    {
        es->p = p;
        ccl_send(tpcb, es);
    }
    else
    {
        struct pbuf *ptr;
        ptr = es->p;
        pbuf_chain(ptr,p);
    }
      ret_err = ERR_OK;
  }
  else if(es->state == ES_CLOSING)
  {
    tcp_recved(tpcb, p->tot_len);
    es->p = NULL;
    pbuf_free(p);
    ret_err = ERR_OK;
  }
  else
  {
    tcp_recved(tpcb, p->tot_len);
    es->p = NULL;
    pbuf_free(p);
    ret_err = ERR_OK;
  }
  return ret_err;
}

void ccl_error(void *arg, err_t err)
{
  struct ccl_state *es;
  LWIP_UNUSED_ARG(err);
  es = (struct ccl_state *)arg;
  if (es != NULL)
  {
    mem_free(es);
  }
}

void ccl_close(struct tcp_pcb *tpcb, struct ccl_state *es)
{
  tcp_arg(tpcb, NULL);
  tcp_sent(tpcb, NULL);
  tcp_recv(tpcb, NULL);
  tcp_err(tpcb, NULL);
  tcp_poll(tpcb, NULL, 0);

  if (es != NULL)
  {
    mem_free(es);
  }
  tcp_close(tpcb);
}

void ccl_send(struct tcp_pcb *tpcb, struct ccl_state *es)
{
    struct pbuf *ptr;
    err_t wr_err = ERR_OK;
    while ((wr_err == ERR_OK) &&
             (es->p != NULL) &&
             (es->p->len <= tcp_sndbuf(tpcb)))
      {
      ptr = es->p;
      wr_err = tcp_write(tpcb, ptr->payload, ptr->len, 1);
      tcp_output(tpcb);
      if (wr_err == ERR_OK)
      {
         u16_t plen;
         u8_t freed;
         plen = ptr->len;
         es->p = ptr->next;
         if(es->p != NULL)
         {
             pbuf_ref(es->p);
         }
         do
          {
            freed = pbuf_free(ptr);
          } while(freed == 0);
         tcp_recved(tpcb, plen);
       }
       else if(wr_err == ERR_MEM)
       {
         es->p = ptr;
       }
       else
       {
       }
    }
}

void local_center_init(void)
{
  ccl_pcb = tcp_new();

  sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
  sciDisplayText(sciREGx, (uint8_t*)"NEW PCB", sizeof("NEW PCB"));
  sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));

  if (ccl_pcb != NULL)
  {
    err_t err;

    struct ip_addr remota;
    IP4_ADDR(&remota,0,0,0,0);
    err = tcp_bind(ccl_pcb,&remota,200);

    if (err == ERR_OK)
    {
      ccl_pcb = tcp_listen(ccl_pcb);
      tcp_accept(ccl_pcb, ccl_accept);
    }
    else
    {
    }
  }
  else
  {
  }
}

void EMAC_LwIP_Main (uint8_t * macAddress)
{
   unsigned int   ipAddr;
   struct in_addr devIPAddress;

   sciInit();

 IntMasterIRQEnable();
 _enable_FIQ();

 sciDisplayText(sciREGx, txtEnetInit, sizeof(txtEnetInit));

 ipAddr = lwIPInit(0, macAddress, 0, 0, 0, IPADDR_USE_DHCP);

 sciDisplayText(sciREGx, (uint8_t*)"..WAIT", sizeof("..WAIT"));
 sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));

 if (0 == ipAddr) {
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
   sciDisplayText(sciREGx, txtErrorInit, sizeof(txtErrorInit));
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
 } else {

   devIPAddress.s_addr = ipAddr;
   txtIPAddrItoA = (uint8_t *)inet_ntoa(devIPAddress);

   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));

   sciDisplayText(sciREGx, txtTitle, sizeof(txtTitle));
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));

   sciDisplayText(sciREGx, txtTI, sizeof(txtTI));
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));

   sciDisplayText(sciREGx, txtLittleEndian, sizeof(txtLittleEndian));
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));

   sciDisplayText(sciREGx, txtIPAddrTxt, sizeof(txtIPAddrTxt));
   sciDisplayText(sciREGx, txtIPAddrItoA, 16);
   sciDisplayText(sciREGx, txtCRLF, sizeof(txtCRLF));

   local_center_init();

while (1) {}
 }
}