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--- iothings:laboratoare:2025:lab4 [2025/10/14 14:34]
dan.tudose [CoAP Server]
+++ iothings:laboratoare:2025:lab4 [2025/10/28 11:29] (current)
dan.tudose [CoAP Server]
@@ Line 80: / Line 80: @@
 On the CoAP side, the library handles all the protocol details—message type, message ID, token management, options, and parsing—so your sketch only deals with high-level actions. You issue a client request with coap.get(remoteIP, 5683, ""), and when the server replies, the callback receives a parsed CoapPacket. The code prints the CoAP code (e.g., 2.xx success), basic header info, and the payload as text.
+[[iothings:laboratoare:2025_code:lab4_1|Click here to get the code example]]
-<code C main.cpp>
-#include <Arduino.h>
-#include <WiFi.h>
-#include <WiFiUdp.h>
-#include <coap-simple.h>   // hirotakaster/CoAP simple library
-// ===== Wi-Fi creds =====
-const char* WIFI_SSID = "UPB-Guest";
-const char* WIFI_PASS = "";
-// ===== CoAP server (Californium demo) =====
-const char* COAP_HOST = "californium.eclipseprojects.io";
-const uint16_t COAP_PORT = 5683;   // RFC 7252 default port
-// UDP + CoAP objects
-WiFiUDP udp;
-Coap coap(udp);
-// ----- Response callback: prints payload as text -----
-void onCoapResponse(CoapPacket &packet, IPAddress ip, int port) {
-  // Copy payload into a printable buffer
-  const size_t n = packet.payloadlen;
-  String from = ip.toString() + ":" + String(port);
-  Serial.printf("[CoAP] Response from %s  code=%u (0x%02X)  len=%u\n",
-                from.c_str(), (packet.code >> 5), packet.code, (unsigned)n);
-  if (n > 0) {
-    // Make it printable; not all payloads are ASCII
-    size_t m = n;
-    if (m > 1023) m = 1023;     // clamp for serial
-    char buf[1024];
-    memcpy(buf, packet.payload, m);
-    buf[m] = '\0';
-    Serial.println(F("[CoAP Payload]"));
-    Serial.println(buf);
-  }
-}
-// Re-resolves hostname and sends GET to "/"
-bool coapGetRoot() {
-  IPAddress remote;
-  if (!WiFi.hostByName(COAP_HOST, remote)) {
-    Serial.println(F("[CoAP] DNS failed"));
-    return false;
-  }
-  Serial.printf("[CoAP] GET coap://%s:%u/\n", COAP_HOST, COAP_PORT);
-  // Path is "" for "/", per library examples
-  int msgid = coap.get(remote, COAP_PORT, "");
-  (void)msgid; // not used further in this demo
-  return true;
-}
-unsigned long lastGetMs = 0;
-const unsigned long GET_PERIOD_MS = 10000;
-void setup() {
-  Serial.begin(115200);
-  delay(200);
-  Serial.println(F("\n== CoAP client (Californium demo) =="));
-  // Wi-Fi
-  WiFi.mode(WIFI_STA);
-  WiFi.begin(WIFI_SSID, WIFI_PASS);
-  Serial.print(F("Connecting"));
-  while (WiFi.status() != WL_CONNECTED) { delay(300); Serial.print('.'); }
-  Serial.println();
-  Serial.print(F("Wi-Fi OK. IP: ")); Serial.println(WiFi.localIP());
-  // Bind UDP so we can receive responses (use standard CoAP port or 0 for ephemeral)
-  udp.begin(5683);
-  // Register response handler and start CoAP
-  coap.response(onCoapResponse);
-  coap.start();
-  // First GET right away
-  coapGetRoot();
-  lastGetMs = millis();
-}
-void loop() {
-  // Let the library process incoming UDP (and fire onCoapResponse)
-  coap.loop();
-  // Periodic GET
-  unsigned long now = millis();
-  if (now - lastGetMs >= GET_PERIOD_MS) {
-    lastGetMs = now;
-    coapGetRoot();
-  }
-}
-</code>
 After building, you should get a similar print-out in the console:
@@ Line 195: / Line 102: @@
 **Debian/Ubuntu**
-   sudo apt update\\
+   sudo apt update
-   sudo apt install -y libcoap2-bin\\
+   sudo apt install -y libcoap2-bin
    # binaries: coap-client, coap-server
 **macOS**
-   # needs Homebrew: https://brew.sh\\
+   # needs Homebrew: https://brew.sh
-   brew update\\
+   brew update
-   brew install libcoap\\
+   brew install libcoap
    # binaries: coap-client, coap-server
 **Windows**
-   # Install WSL (once)\\
+   # Install WSL (once)
-   wsl --install\\
+   wsl --install
-   # Open Ubuntu in WSL, then:\\
+   # Open Ubuntu in WSL, then:
-   sudo apt update\\
+   sudo apt update
-   sudo apt install -y libcoap2-bin\\
+   sudo apt install -y libcoap2-bin
 </note>
-<code C main.cpp>
+[[iothings:laboratoare:2025_code:lab4_2|Click here to get the code example.]]
-#include <Arduino.h>
-#include <WiFi.h>
-#include <WiFiUdp.h>
-#include <Adafruit_NeoPixel.h>
-#include <coap-simple.h>   // hirotakaster CoAP simple library
-// ===== Wi-Fi creds =====
-const char* WIFI_SSID = "UPB-Guest";
-const char* WIFI_PASS = "";
-// ===== UDP + CoAP objects =====
+Test it from your computer with the following commands, where esp-ip is the IP the node prints after connecting in the serial terminal:
-WiFiUDP udp;
-Coap coap(udp);
-// ===== On-board NeoPixel (GPIO 3) =====
+<code>
-constexpr uint8_t kNeoPixelPin = 3;
+# discovery
-constexpr uint8_t kNeoPixelCount = 1;
+coap-client -v9 -m get -A 40 coap://<esp-ip>/.well-known/core
-constexpr uint8_t kNeoPixelBrightness = 128; // 50% to limit power draw
-Adafruit_NeoPixel g_pixel(kNeoPixelCount, kNeoPixelPin, NEO_GRB + NEO_KHZ800);
+# other resources
-bool g_pixelReady = false;
+coap-client -v9 -m get coap://<esp-ip>/sys/uptime
+coap-client -v9 -m get coap://<esp-ip>/net/rssi
+coap-client -v9 -m get coap://<esp-ip>/led
+coap-client -v9 -m put -e "on"  coap://<esp-ip>/led
+coap-client -v9 -m put -e "off" coap://<esp-ip>/led
+coap-client -v9 -m post -e "hello" coap://<esp-ip>/echo
-// ===== Simple LED state =====
+</code>
-static bool g_ledOn = false;
-void applyLedState() {
+<note>**Assignment 1:**
-  if (!g_pixelReady) {
+Add BME680 functionality to this code in order to query sensor values through CoAP. They should be available at /sensors/temperature, /sensors/humidity, /sensors/pressure
-    return;
+</note>
-  }
-  if (g_ledOn) {
-    g_pixel.setPixelColor(0, g_pixel.Color(255, 255, 255));
-  } else {
-    g_pixel.setPixelColor(0, 0, 0, 0);
-  }
-  g_pixel.show();
-}
-// ----- helper: send text/plain 2.05 Content -----
+<note>**Assignment 2:**
-static void coapSendText(IPAddress ip, int port, const CoapPacket& req,
+Build a web page that acts as a GUI for your coap-client queries (e.g. you can do discovery, get and put/post from the page. You will probably need a proxy to translate coap datagrams to WS or HTTP.
-                         const char* text) {
+</note>
-  Serial.printf("[CoAP] Replying to %s:%d mid=%u code=%u tokensz=%u\n",
-                ip.toString().c_str(), port, req.messageid, req.code, req.tokenlen);
-  coap.sendResponse(
-    ip, port, req.messageid,
-    text, strlen(text),
-    COAP_RESPONSE_CODE(205),      // 2.05 Content
-    COAP_TEXT_PLAIN,
-    req.token, req.tokenlen
-  );
-}
-// ----- /sys/uptime (GET) -----
-void h_sys_uptime(CoapPacket &packet, IPAddress ip, int port) {
-  unsigned long secs = millis() / 1000UL;
-  char buf[32];
-  snprintf(buf, sizeof(buf), "%lu", (unsigned long)secs);
-  coapSendText(ip, port, packet, buf);
-}
-// ----- /net/rssi (GET) -----
+<hidden>
-void h_net_rssi(CoapPacket &packet, IPAddress ip, int port) {
-  long rssi = WiFi.RSSI();
-  char buf[16];
-  snprintf(buf, sizeof(buf), "%ld", rssi);
-  coapSendText(ip, port, packet, buf);
-}
-// ----- /led (GET state, PUT/POST "on" or "off") -----
+For assignment 2, run the above ESP32 code example and get the board IP. Run the python proxy script below (edit it in advance and specify the ESP IP - COAP_HOST).
-void h_led(CoapPacket &packet, IPAddress ip, int port) {
-  if (packet.code == COAP_GET) {
-    coapSendText(ip, port, packet, g_ledOn ? "on" : "off");
-    return;
-  }
-  if (packet.code == COAP_PUT || packet.code == COAP_POST) {
+[[iothings:laboratoare:2025_code:lab4_proxy|Python proxy script]]
-    String body;
-    body.reserve(packet.payloadlen + 1);
-    for (size_t i = 0; i < packet.payloadlen; ++i) body += (char)packet.payload[i];
-    body.trim();
-    if (body.equalsIgnoreCase("on"))  g_ledOn = true;
-    if (body.equalsIgnoreCase("off")) g_ledOn = false;
-    applyLedState();
-    // Acknowledge change (2.04 Changed) and return new state
+Then open the webpage [[https://dantudose.github.io/labs/lab4_1.html|here]] and edit the following fields:
-    const char* state = g_ledOn ? "on" : "off";
+Proxy base URL:   http://localhost:8080
-    coap.sendResponse(
+CoAP host:        ESP32_IP - from serial terminal
-      ip, port, packet.messageid,
-      state, strlen(state),
-      COAP_RESPONSE_CODE(204),      // 2.04 Changed
-      COAP_TEXT_PLAIN,
-      packet.token, packet.tokenlen
-    );
-    return;
-  }
-  // Method not allowed
-  coap.sendResponse(
-    ip, port, packet.messageid,
-    "Method Not Allowed", 18,
-    COAP_RESPONSE_CODE(405),
-    COAP_TEXT_PLAIN,
-    packet.token, packet.tokenlen
-  );
-}
-// ----- /echo (POST/PUT echoes payload; GET returns hint) -----
+</hidden>
-void h_echo(CoapPacket &packet, IPAddress ip, int port) {
-  if (packet.payloadlen == 0 || packet.code == COAP_GET) {
-    const char* hint = "POST/PUT a payload and I'll echo it.";
-    coapSendText(ip, port, packet, hint);
-    return;
-  }
-  coap.sendResponse(
-    ip, port, packet.messageid,
-    (const char*)packet.payload, packet.payloadlen,
-    COAP_RESPONSE_CODE(205),      // 2.05 Content
-    COAP_TEXT_PLAIN,
-    packet.token, packet.tokenlen
-  );
-}
-// ----- /.well-known/core (RFC 6690 CoRE Link Format) -----
-void h_wkc(CoapPacket &packet, IPAddress ip, int port) {
-  Serial.printf("[CoAP] Discovery hit from %s:%d type=%u code=%u accept=%s\n",
-                ip.toString().c_str(),
-                port,
-                packet.type,
-                packet.code,
-                packet.optionnum ? "yes" : "no");
-  // Advertise resources and basic attributes
-  const char* linkfmt =
-    "</sys/uptime>;rt=\"sys.uptime\";if=\"core.a\";ct=0,"
-    "</net/rssi>;rt=\"net.rssi\";if=\"core.a\";ct=0,"
-    "</led>;rt=\"dev.led\";if=\"core.a\";ct=0,"
-    "</echo>;rt=\"util.echo\";if=\"core.p\";ct=0";
-  coap.sendResponse(
-    ip, port, packet.messageid,
-    linkfmt, strlen(linkfmt),
-    COAP_RESPONSE_CODE(205),
-    COAP_APPLICATION_LINK_FORMAT, // ct=40
-    packet.token, packet.tokenlen
-  );
-}
-void setup() {
-  Serial.begin(115200);
-  delay(200);
-  Serial.println("\n== CoAP RESTful mapping & discovery (server-only) ==");
-  // Wi-Fi
-  WiFi.mode(WIFI_STA);
-  WiFi.begin(WIFI_SSID, WIFI_PASS);
-  Serial.print("Connecting");
-  while (WiFi.status() != WL_CONNECTED) { delay(300); Serial.print("."); }
-  Serial.println();
-  Serial.print("Wi-Fi OK. IP: "); Serial.println(WiFi.localIP());
-  Serial.printf("Listening for CoAP on udp/%d\n", COAP_DEFAULT_PORT);
-  g_pixel.begin();
-  g_pixel.setBrightness(kNeoPixelBrightness);
-  g_pixel.clear();
-  g_pixel.show();
-  g_pixelReady = true;
-  applyLedState();
-  // Start CoAP server on udp/5683
-  udp.begin(5683);
-  // Register resources
-  coap.server(h_sys_uptime, "sys/uptime");
-  coap.server(h_net_rssi,   "net/rssi");
-  coap.server(h_led,        "led");
-  coap.server(h_echo,       "echo");
-  coap.server(h_wkc,        ".well-known/core"); // discovery
-  // Start CoAP stack
-  coap.start();
-}
-void loop() {
-  // Process incoming CoAP requests
-  coap.loop();
-}
-</code>
-Test it from your computer with the following commands, where esp-ip is the IP the node prints after connecting in the serial terminal:
-<code>
-# discovery
-coap-client -v9 -m get -A 40 coap://<esp-ip>/.well-known/core
-# other resources
-coap-client -m get coap://<esp-ip>/sys/uptime
-coap-client -m get coap://<esp-ip>/net/rssi
-coap-client -m get coap://<esp-ip>/led
-coap-client -m put -e "on"  coap://<esp-ip>/led
-coap-client -m put -e "off" coap://<esp-ip>/led
-coap-client -m post -e "hello" coap://<esp-ip>/echo
-</code>