lwip udp server does not send big data correctly
hello
I have implemented a udp server on stm32h7 using raw lwip.my function is reading data from sd memory and sending to pc, so I read a block(512bytes) of data from sd memory by f_read function of fatfs and send it using udp_send to remote host.everything is OK with reading data from sd memory, but when I want to send for example a 2kbyte file from sd to PC, I receive only 1636bytes on pc. I use udp terminal of matlab. when I check the received data it shows that only firs 512 received bytes are correct and other received bytes seems to be a peice of next 512byte read from sd memory.here is the code I wrote for
///////////////////////////////////////////////////////////////
#define SD_read_buffer 512
udp_server_send.
struct pbuf *p_tx;
struct pbuf *sb;
char *c;
int i;
char data_read[10]={0};
/* allocate pbuf from RAM*/
p_tx = pbuf_alloc(PBUF_TRANSPORT,p->len, PBUF_RAM);
sb = pbuf_alloc(PBUF_TRANSPORT,512, PBUF_RAM);
if(p_tx != NULL)
{
pbuf_take(p_tx, (char*)p->payload, p->len);
/* Connect to the remote client */
udp_connect(upcb, addr, 4023);
/* Tell the client that we have accepted it */
c = p->payload;
for( i = 0 ; i < p->len ; i++)
{
data_read[i] = c[i];
}
if(data_read[0]=='9')
{
HAL_Delay(2000);
// f_open(&SDFile, "REC_2K.DAT", FA_READ); //640kb file
f_open(&SDFile, "RECORD_1.DAT", FA_READ);//5kb file
for (;;)
{
f_read(&SDFile, SD_read_buffer, sizeof SD_read_buffer, &br); /* Read a chunk of data from the source file */
if (br == 0) break; /* error or eof */
memcpy(sb->payload,SD_read_buffer,sizeof SD_read_buffer);
udp_send(upcb, sb);
HAL_GPIO_TogglePin(GPIOE,GPIO_PIN_8);
}
f_close(&SDFile);
data_read[0]=0;
}
/* free the UDP connection, so we can accept new clients */
udp_disconnect(upcb);
/* Free the p_tx buffer */
pbuf_free(p_tx);
pbuf_free(sb);
/* Free the p buffer */
pbuf_free(p);
//////////////////////////////////////////////////////////////
I added 100ms delay before and after udp_send, but it did not fixed the problem, so the problem is not about time. but when I add pbuf_alloc of sb pbuf before f_read the received data have the same size of sent.but it allocate extra memory in every loop and fill the ram, so its not the solution.
would someone give me a hint or a solution about this problem?
thank u before
