Add device-dashboard

tutorials/device-dashboard/realtime-graph/server.c

@@ -0,0 +1,72 @@
+// SPDX-FileCopyrightText: 2026 Cesanta Software Limited
+// SPDX-License-Identifier: GPL-2.0-only or commercial
+
+#include "math.h"
+#include "mongoose.h"
+
+#if MG_ARCH == MG_ARCH_UNIX || MG_ARCH == MG_ARCH_WIN32
+#define HTTP_ADDR "http://0.0.0.0:8000"
+#else
+#define HTTP_ADDR "http://0.0.0.0:80"
+#endif
+
+#define NUM_POINTS 512   // How many data points to send
+#define INTERVAL_MS 200  // How often, in milliseconds
+
+struct point {
+  uint16_t x;   // X coordinate of the data point, usually this is time
+  uint16_t y1;  // We can plot multiple values per graph,
+  uint16_t y2;  // let's plot 2 values: y1 and y2.
+};
+
+// This function prints a JSON array of plot points
+size_t print_points(void (*fn)(char, void *), void *arg, va_list *ap) {
+  size_t i, n = 0;
+  const char *comma = "";
+  (void) ap;
+  n += mg_xprintf(fn, arg, "[");
+  for (i = 0; i < NUM_POINTS; i++) {
+    struct point p;
+    p.x = (uint16_t) i;
+    // rand() - 0.5 + sin(x * 0.00002) * 40 + sin(x * 0.001) * 5 + sin(x * 0.1)
+    // * 2;
+    p.y1 = 100 + 50 * sin(i * 0.1) + rand() % 21;
+    p.y2 = 70 + 30 * sin(i * 0.03) + rand() % 17;
+    n += mg_xprintf(fn, arg, "%s[%hu,%hu,%hu]", comma, p.x, p.y1, p.y2);
+    comma = ",";
+  }
+  n += mg_xprintf(fn, arg, "]");
+  return n;
+}
+
+static void get_points(union mg_val *val) {
+  val->fn = (void (*)(void)) print_points;
+}
+
+// Modify this. This represents device's state to the dashboard
+static struct mg_field fields[] = {
+    {"points", MG_VAL_FN, get_points, NULL},
+    {NULL, 0, 0, 0},
+};
+
+void run_mongoose(void) {
+  struct mg_mgr mgr;
+  struct mg_dash dash = {fields};
+  mg_mgr_init(&mgr);
+  mg_http_listen(&mgr, "http://0.0.0.0:8000", mg_dash_ev_handler, &dash);
+
+  uint64_t timer = 0;
+  for (;;) {
+    mg_mgr_poll(&mgr, 10);
+
+    // Send WS change notifications periodically
+    if (mg_timer_expired(&timer, INTERVAL_MS, mg_now())) {
+      mg_dash_send_change(&mgr, mg_dash_find_field(fields, mg_str("points")));
+    }
+  }
+}
+
+int main(void) {
+  run_mongoose();
+  return 0;
+}