Wifi, TCP-Client and Ping/Pong

2026-05-12 14:17:44 +02:00
parent 95ffb6cecb
commit 5d9d3e205b
4 changed files with 290 additions and 0 deletions
@@ -0,0 +1,137 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "pico/stdlib.h"
+#include "pico/cyw43_arch.h"
+
+#include "lwip/pbuf.h"
+#include "lwip/tcp.h"
+
+#define SERVER_IP   "192.168.161.25"
+#define SERVER_PORT 8080
+
+typedef struct {
+    struct tcp_pcb *pcb;
+    ip_addr_t       remote;
+    volatile bool   done;
+} client_t;
+
+static void finish(client_t *c) {
+    if (c->pcb) {
+        tcp_arg(c->pcb, NULL);
+        tcp_recv(c->pcb, NULL);
+        tcp_err(c->pcb, NULL);
+        tcp_close(c->pcb);
+        c->pcb = NULL;
+    }
+    c->done = true;
+}
+
+static void send_line(struct tcp_pcb *pcb, const char *msg) {
+    err_t err = tcp_write(pcb, msg, strlen(msg), TCP_WRITE_FLAG_COPY);
+    if (err == ERR_OK) {
+        tcp_output(pcb);
+    } else {
+        printf("tcp_write err=%d\n", err);
+    }
+}
+
+static err_t on_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err) {
+    client_t *c = (client_t *)arg;
+    if (!p) {
+        printf("Server hat Verbindung geschlossen\n");
+        finish(c);
+        return ERR_OK;
+    }
+
+    char buf[64];
+    uint16_t n = pbuf_copy_partial(p, buf, sizeof(buf) - 1, 0);
+    buf[n] = '\0';
+
+    printf("<< %s", buf);
+
+    if (strstr(buf, "ping")) {
+        printf(">> pong\n");
+        send_line(pcb, "pong\n");
+    }
+
+    tcp_recved(pcb, p->tot_len);
+    pbuf_free(p);
+    return ERR_OK;
+}
+
+static void on_err(void *arg, err_t err) {
+    client_t *c = (client_t *)arg;
+    printf("TCP-Fehler: %d\n", err);
+    // lwIP hat das pcb in diesem Callback bereits freigegeben.
+    c->pcb = NULL;
+    c->done = true;
+}
+
+static err_t on_connected(void *arg, struct tcp_pcb *pcb, err_t err) {
+    client_t *c = (client_t *)arg;
+    if (err != ERR_OK) {
+        printf("connect-Callback err=%d\n", err);
+        finish(c);
+        return err;
+    }
+    printf("Verbunden — sende Hallo\n");
+    const char *msg = "Hallo vom Pico 2W\n";
+    err = tcp_write(pcb, msg, strlen(msg), TCP_WRITE_FLAG_COPY);
+    if (err == ERR_OK) {
+        tcp_output(pcb);
+    } else {
+        printf("tcp_write err=%d\n", err);
+    }
+    return err;
+}
+
+int main(void) {
+    stdio_init_all();
+    sleep_ms(2000); // Zeit, das USB-Serial-Terminal zu oeffnen
+
+    if (cyw43_arch_init()) {
+        printf("cyw43_arch_init fehlgeschlagen\n");
+        return 1;
+    }
+    cyw43_arch_enable_sta_mode();
+
+    printf("Verbinde mit WLAN \"%s\"...\n", WIFI_SSID);
+    if (cyw43_arch_wifi_connect_timeout_ms(WIFI_SSID, WIFI_PASSWORD,
+                                           CYW43_AUTH_WPA2_AES_PSK, 30000)) {
+        printf("WLAN-Verbindung fehlgeschlagen\n");
+        return 1;
+    }
+    printf("WLAN OK\n");
+
+    client_t client = {0};
+    if (!ip4addr_aton(SERVER_IP, &client.remote)) {
+        printf("Ungueltige Server-IP\n");
+        return 1;
+    }
+
+    client.pcb = tcp_new_ip_type(IP_GET_TYPE(&client.remote));
+    if (!client.pcb) {
+        printf("tcp_new fehlgeschlagen\n");
+        return 1;
+    }
+    tcp_arg(client.pcb, &client);
+    tcp_recv(client.pcb, on_recv);
+    tcp_err(client.pcb, on_err);
+
+    printf("Verbinde TCP %s:%d\n", SERVER_IP, SERVER_PORT);
+    cyw43_arch_lwip_begin();
+    err_t err = tcp_connect(client.pcb, &client.remote, SERVER_PORT, on_connected);
+    cyw43_arch_lwip_end();
+    if (err != ERR_OK) {
+        printf("tcp_connect err=%d\n", err);
+        return 1;
+    }
+
+    while (!client.done) {
+        sleep_ms(100);
+    }
+
+    cyw43_arch_deinit();
+    return 0;
+}