Add BLE stream classes.

Co-authored-by: doudar <17362216+doudar@users.noreply.github.com>

Author: h2zero

.gitignore

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 docs/doxydocs
 .development
+_codeql_detected_source_root

examples/NimBLE_Stream_Client/NimBLE_Stream_Client.ino

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+/**
+ *  NimBLE_Stream_Client Example:
+ *
+ *  Demonstrates using NimBLEStreamClient to connect to a BLE GATT server
+ *  and communicate using the Arduino Stream interface.
+ *
+ *  This allows you to use familiar methods like print(), println(),
+ *  read(), and available() over BLE, similar to how you would use Serial.
+ *
+ *  This example connects to the NimBLE_Stream_Server example.
+ *
+ *  Created: November 2025
+ *      Author: NimBLE-Arduino Contributors
+ */
+
+#include <Arduino.h>
+#include <NimBLEDevice.h>
+
+// Service and Characteristic UUIDs (must match the server)
+#define SERVICE_UUID        "6E400001-B5A3-F393-E0A9-E50E24DCCA9E"
+#define CHARACTERISTIC_UUID "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
+
+// Create the stream client instance
+NimBLEStreamClient bleStream;
+
+// Connection state variables
+static bool                          doConnect     = false;
+static bool                          connected     = false;
+static const NimBLEAdvertisedDevice* pServerDevice = nullptr;
+static NimBLEClient*                 pClient       = nullptr;
+
+/** Scan callbacks to find the server */
+class ScanCallbacks : public NimBLEScanCallbacks {
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) override {
+        Serial.printf("Advertised Device: %s\n", advertisedDevice->toString().c_str());
+
+        // Check if this device advertises our service
+        if (advertisedDevice->isAdvertisingService(NimBLEUUID(SERVICE_UUID))) {
+            Serial.println("Found our stream server!");
+            pServerDevice = advertisedDevice;
+            NimBLEDevice::getScan()->stop();
+            doConnect = true;
+        }
+    }
+
+    void onScanEnd(const NimBLEScanResults& results, int reason) override {
+        Serial.println("Scan ended");
+        if (!doConnect && !connected) {
+            Serial.println("Server not found, restarting scan...");
+            NimBLEDevice::getScan()->start(5, false, true);
+        }
+    }
+} scanCallbacks;
+
+/** Client callbacks for connection/disconnection events */
+class ClientCallbacks : public NimBLEClientCallbacks {
+    void onConnect(NimBLEClient* pClient) override {
+        Serial.println("Connected to server");
+        // Update connection parameters for better throughput
+        pClient->updateConnParams(12, 24, 0, 200);
+    }
+
+    void onDisconnect(NimBLEClient* pClient, int reason) override {
+        Serial.printf("Disconnected from server, reason: %d\n", reason);
+        connected = false;
+        bleStream.end();
+
+        // Restart scanning
+        Serial.println("Restarting scan...");
+        NimBLEDevice::getScan()->start(5, false, true);
+    }
+} clientCallbacks;
+
+/** Connect to the BLE Server and set up the stream */
+bool connectToServer() {
+    Serial.printf("Connecting to: %s\n", pServerDevice->getAddress().toString().c_str());
+
+    // Create or reuse a client
+    pClient = NimBLEDevice::getClientByPeerAddress(pServerDevice->getAddress());
+    if (!pClient) {
+        pClient = NimBLEDevice::createClient();
+        if (!pClient) {
+            Serial.println("Failed to create client");
+            return false;
+        }
+        pClient->setClientCallbacks(&clientCallbacks, false);
+        pClient->setConnectionParams(12, 24, 0, 200);
+        pClient->setConnectTimeout(5000);
+    }
+
+    // Connect to the remote BLE Server
+    if (!pClient->connect(pServerDevice)) {
+        Serial.println("Failed to connect to server");
+        return false;
+    }
+
+    Serial.println("Connected! Discovering services...");
+
+    // Get the service and characteristic
+    NimBLERemoteService* pRemoteService = pClient->getService(SERVICE_UUID);
+    if (!pRemoteService) {
+        Serial.println("Failed to find our service UUID");
+        pClient->disconnect();
+        return false;
+    }
+    Serial.println("Found the stream service");
+
+    NimBLERemoteCharacteristic* pRemoteCharacteristic = pRemoteService->getCharacteristic(CHARACTERISTIC_UUID);
+    if (!pRemoteCharacteristic) {
+        Serial.println("Failed to find our characteristic UUID");
+        pClient->disconnect();
+        return false;
+    }
+    Serial.println("Found the stream characteristic");
+
+    /**
+     * Initialize the stream client with the remote characteristic
+     * subscribeNotify=true means we'll receive notifications in the RX buffer
+     */
+    if (!bleStream.begin(pRemoteCharacteristic, true)) {
+        Serial.println("Failed to initialize BLE stream!");
+        pClient->disconnect();
+        return false;
+    }
+
+    Serial.println("BLE Stream initialized successfully!");
+    connected = true;
+    return true;
+}
+
+void setup() {
+    Serial.begin(115200);
+    Serial.println("Starting NimBLE Stream Client");
+
+    /** Initialize NimBLE */
+    NimBLEDevice::init("NimBLE-StreamClient");
+
+    /**
+     * Create the BLE scan instance and set callbacks
+     * Configure scan parameters
+     */
+    NimBLEScan* pScan = NimBLEDevice::getScan();
+    pScan->setScanCallbacks(&scanCallbacks, false);
+    pScan->setInterval(100);
+    pScan->setWindow(99);
+    pScan->setActiveScan(true);
+
+    /** Start scanning for the server */
+    Serial.println("Scanning for BLE Stream Server...");
+    pScan->start(5, false, true);
+}
+
+void loop() {
+    // If we found a server, try to connect
+    if (doConnect) {
+        doConnect = false;
+        if (connectToServer()) {
+            Serial.println("Stream ready for communication!");
+        } else {
+            Serial.println("Failed to connect to server, restarting scan...");
+            pServerDevice = nullptr;
+            NimBLEDevice::getScan()->start(5, false, true);
+        }
+    }
+
+    // If we're connected, demonstrate the stream interface
+    if (connected && bleStream) {
+        // Check if we received any data from the server
+        if (bleStream.available()) {
+            Serial.print("Received from server: ");
+
+            // Read all available data (just like Serial.read())
+            while (bleStream.available()) {
+                char c = bleStream.read();
+                Serial.write(c);
+            }
+            Serial.println();
+        }
+
+        // Send a message every 5 seconds using Stream methods
+        static unsigned long lastSend = 0;
+        if (millis() - lastSend > 5000) {
+            lastSend = millis();
+
+            // Using familiar Serial-like methods!
+            bleStream.print("Hello from client! Uptime: ");
+            bleStream.print(millis() / 1000);
+            bleStream.println(" seconds");
+
+            Serial.println("Sent data to server via BLE stream");
+        }
+
+        // You can also read from Serial and send over BLE
+        if (Serial.available()) {
+            Serial.println("Reading from Serial and sending via BLE:");
+            while (Serial.available()) {
+                char c = Serial.read();
+                Serial.write(c);    // Echo locally
+                bleStream.write(c); // Send via BLE
+            }
+            Serial.println();
+        }
+    }
+
+    delay(10);
+}

examples/NimBLE_Stream_Client/README.md

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+# NimBLE Stream Client Example
+
+This example demonstrates how to use the `NimBLEStreamClient` class to connect to a BLE GATT server and communicate using the familiar Arduino Stream interface.
+
+## Features
+
+- Uses Arduino Stream interface (print, println, read, available, etc.)
+- Automatic server discovery and connection
+- Bidirectional communication
+- Buffered TX/RX using ring buffers
+- Automatic reconnection on disconnect
+- Similar usage to Serial communication
+
+## How it Works
+
+1. Scans for BLE devices advertising the target service UUID
+2. Connects to the server and discovers the stream characteristic
+3. Initializes `NimBLEStreamClient` with the remote characteristic
+4. Subscribes to notifications to receive data in the RX buffer
+5. Uses familiar Stream methods like `print()`, `println()`, `read()`, and `available()`
+
+## Usage
+
+1. First, upload the NimBLE_Stream_Server example to one ESP32
+2. Upload this client sketch to another ESP32
+3. The client will automatically:
+   - Scan for the server
+   - Connect when found
+   - Set up the stream interface
+   - Begin bidirectional communication
+4. You can also type in the Serial monitor to send data to the server
+
+## Service UUIDs
+
+Must match the server:
+- Service: `6E400001-B5A3-F393-E0A9-E50E24DCCA9E`
+- Characteristic: `6E400002-B5A3-F393-E0A9-E50E24DCCA9E`
+
+## Serial Monitor Output
+
+The example displays:
+- Server discovery progress
+- Connection status
+- All data received from the server
+- Confirmation of data sent to the server
+
+## Testing
+
+Run with NimBLE_Stream_Server to see bidirectional communication:
+- Server sends periodic status messages
+- Client sends periodic uptime messages
+- Both echo data received from each other
+- You can send data from either Serial monitor

examples/NimBLE_Stream_Echo/NimBLE_Stream_Echo.ino

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+/**
+ *  NimBLE_Stream_Echo Example:
+ *
+ *  A minimal example demonstrating NimBLEStreamServer.
+ *  Echoes back any data received from BLE clients.
+ *
+ *  This is the simplest way to use the NimBLE Stream interface,
+ *  showing just the essential setup and read/write operations.
+ *
+ *  Created: November 2025
+ *      Author: NimBLE-Arduino Contributors
+ */
+
+#include <Arduino.h>
+#include <NimBLEDevice.h>
+
+NimBLEStreamServer bleStream;
+
+void setup() {
+    Serial.begin(115200);
+    Serial.println("NimBLE Stream Echo Server");
+
+    // Initialize BLE
+    NimBLEDevice::init("BLE-Echo");
+    auto pServer = NimBLEDevice::createServer();
+    pServer->advertiseOnDisconnect(true); // Keep advertising after clients disconnect
+
+    /**
+     * Initialize the stream server with:
+     * - Service UUID
+     * - Characteristic UUID
+     * - txBufSize: 1024 bytes for outgoing data (notifications)
+     * - rxBufSize: 1024 bytes for incoming data (writes)
+     * - secure: false (no encryption required - set to true for secure connections)
+     */
+    if (!bleStream.begin(NimBLEUUID(uint16_t(0xc0de)), // Service UUID
+                         NimBLEUUID(uint16_t(0xfeed)), // Characteristic UUID
+                         1024,                         // txBufSize
+                         1024,                         // rxBufSize
+                         false)) {                     // secure
+        Serial.println("Failed to initialize BLE stream");
+        return;
+    }
+
+    // Start advertising
+    NimBLEDevice::getAdvertising()->start();
+    Serial.println("Ready! Connect with a BLE client and send data.");
+}
+
+void loop() {
+    // Echo any received data back to the client
+    if (bleStream.ready() && bleStream.available()) {
+        Serial.print("Echo: ");
+        while (bleStream.available()) {
+            char c = bleStream.read();
+            Serial.write(c);
+            bleStream.write(c); // Echo back
+        }
+        Serial.println();
+    }
+    delay(10);
+}

examples/NimBLE_Stream_Echo/README.md

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+# NimBLE Stream Echo Example
+
+This is the simplest example demonstrating `NimBLEStreamServer`. It echoes back any data received from BLE clients.
+
+## Features
+
+- Minimal code showing essential NimBLE Stream usage
+- Echoes all received data back to the client
+- Uses default service and characteristic UUIDs
+- Perfect starting point for learning the Stream interface
+
+## How it Works
+
+1. Initializes BLE with minimal configuration
+2. Creates a stream server with default UUIDs
+3. Waits for client connection and data
+4. Echoes received data back to the client
+5. Displays received data on Serial monitor
+
+## Default UUIDs
+
+- Service: `0xc0de`
+- Characteristic: `0xfeed`
+
+## Usage
+
+1. Upload this sketch to your ESP32
+2. Connect with a BLE client app (nRF Connect, Serial Bluetooth Terminal, etc.)
+3. Find the service `0xc0de` and characteristic `0xfeed`
+4. Subscribe to notifications
+5. Write data to the characteristic
+6. The data will be echoed back and displayed in Serial monitor
+
+## Good For
+
+- Learning the basic NimBLE Stream API
+- Testing BLE connectivity
+- Starting point for custom applications
+- Understanding Stream read/write operations