None: How is send data without lwip func.

Hi; i use lwip tcp/ip raw.. tcp_echoserver.c is running my project.It's working no problem. But i want send data while loop in main.c.. i write; while(1) { mx_lwip_process(); hal_delay(250); tcp_write(pcb,"lalala",6,1); } this code with is not receive data from pc(telnet) static err_t tcp_server_poll(void *arg, struct tcp_pcb *pcb) { tcp_write(pcb,"lalala",6,1); } this code is working, i receive data from pc(telnet) How i