How can I use lwIP tcp/ip stack with microcontroller stm32f4 (client) - tcp

Question

Core: Cortex-M4
Microcontroller: stm32f407 (stm32f4 discovery board)
IP Stack: lwIP 1.4.1
I am using this microcontroller to control an automate and I want to send some information to a separate web server via a HTTP request in the form of:
http://192.168.1.3/api/xdevices.json?SetR=01
lwIP has a http server for the microprocessor, but I'm after the opposite (microcontroller is the client).
I am not sure what i'm doing wrong but after TCP_Connect it always goes to tcp_error handler :
#include "stm32f4xx.h"
/* Include my libraries here */
#include "defines.h"
#include "tm_stm32f4_delay.h"
#include "tm_stm32f4_disco.h"
#include "tm_stm32f4_usart.h"
#include "tm_stm32f4_ethernet.h"
#include "tm_stm32f4_watchdog.h"
#include <stdio.h>
#include <stdlib.h>
#include <lwip/tcp.h>
#include <tcp.h>
uint32_t tcp_send_packet(void);
void tcpErrorHandler(void *arg, err_t err);
err_t tcpSendCallback(void *arg, struct tcp_pcb *tpcb,u16_t len);
err_t connectCallback(void *arg, struct tcp_pcb *tpcb, err_t err);
struct tcp_pcb *testpcb;
first Function is tcp_new :
void tcp_setup(void)
{
uint32_t data = 0xdeadbeef;
/* create an ip */
struct ip_addr ip;
IP4_ADDR(&ip,192,168,1,4); //IP of my PHP server
/* create the control block */
testpcb = tcp_new(); //testpcb is a global struct tcp_pcb
// as defined by lwIP
/* dummy data to pass to callbacks*/
tcp_arg(testpcb, &data);
/* register callbacks with the pcb */
// tcp_recv(testpcb, tcpRecvCallback);
tcp_sent(testpcb, tcpSendCallback);
tcp_err(testpcb, tcpErrorHandler);
/* now connect */
tcp_connect(testpcb, &ip, 21, connectCallback);
TM_DISCO_LedOn(LED_ORANGE);
}
My Callbacks :
void tcpErrorHandler(void *arg, err_t err){
TM_DISCO_LedOn(LED_BLUE);
}
err_t tcpSendCallback(void *arg, struct tcp_pcb *tpcb,u16_t len)
{
TM_DISCO_LedOn(LED_RED);
}
err_t connectCallback(void *arg, struct tcp_pcb *tpcb, err_t err)
{
TM_DISCO_LedOn(LED_RED);
tcp_send_packet();
return 0;
}
my header :
uint32_t tcp_send_packet(void)
{
char *string = "SetR=01\r\n\r\n ";
uint32_t len = strlen(string);
/* push to buffer */
tcp_write(testpcb, string, strlen(string), TCP_WRITE_FLAG_COPY);
/* now send */
tcp_output(testpcb);
return 0;
}
void lwip_init();
Main function :
int main(void) {
/* Initialize system */
SystemInit();
lwip_init();
/* Initialize delay */
TM_DELAY_Init();
/* Initialize leds on board */
TM_DISCO_LedInit();
/* Initialize button */
TM_DISCO_ButtonInit();
while(1) {
tcp_setup();
} }
Clearly i'm forgetting something i just don't know what it is .( i'm using Keil arm)
thank you

Answer 1

Init LwIP with lwip_init
Call tcp_setup outside while loop only once not in while loop to setup only one TCP connection, not unlimited
In while loop, process LwIP incoming data periodically. Since you are using my (TM Tilen Majerle) ethernet wrapper for STM32F4, you should add these lines inside your while loop
/* Check if any packet received */
if (LwIP_CheckFrameReceived()) {
/* Process received ethernet packet */
LwIP_Pkt_Handle();
}
/* Handle periodic timers for LwIP */
LwIP_Periodic_Handle(EthernetLocalTime);
Or call TM_ETHERNET_Update function from your library. Your choice, it works the same.
In your case:
int main() {
....
lwip_init();
tcp_setup();
while (1) {
TM_ETHERNET_Update();
}
}