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https://github.com/h2zero/esp-nimble-cpp.git
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e55ad9019c
L2CAP is the underlying technology powering GATT. BLE 5 exposes L2CAP COC (Connection Oriented Channels) allowing a streaming API that leads to much higher throughputs than you can achieve with updating GATT characteristics. The patch follows the established infrastructure very closely. The main components are: - `NimBLEL2CAPChannel`, encapsulating an L2CAP COC. - `NimBLEL2CAPServer`, encapsulating the L2CAP service. - `Examples/L2CAP`, containing a client and a server application. Apart from these, only minor adjustments to the existing code was necessary.
91 lines
3.2 KiB
C++
91 lines
3.2 KiB
C++
#include <NimBLEDevice.h>
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// See the following for generating UUIDs:
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// https://www.uuidgenerator.net/
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#define SERVICE_UUID "dcbc7255-1e9e-49a0-a360-b0430b6c6905"
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#define CHARACTERISTIC_UUID "371a55c8-f251-4ad2-90b3-c7c195b049be"
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#define L2CAP_CHANNEL 150
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#define L2CAP_MTU 5000
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class GATTCallbacks: public BLEServerCallbacks {
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public:
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void onConnect(BLEServer* pServer, BLEConnInfo& info) {
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/// Booster #1
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pServer->setDataLen(info.getConnHandle(), 251);
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/// Booster #2 (especially for Apple devices)
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BLEDevice::getServer()->updateConnParams(info.getConnHandle(), 12, 12, 0, 200);
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}
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};
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class L2CAPChannelCallbacks: public BLEL2CAPChannelCallbacks {
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public:
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bool connected = false;
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size_t numberOfReceivedBytes;
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uint8_t nextSequenceNumber;
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public:
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void onConnect(NimBLEL2CAPChannel* channel) {
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printf("L2CAP connection established\n");
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connected = true;
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numberOfReceivedBytes = nextSequenceNumber = 0;
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}
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void onRead(NimBLEL2CAPChannel* channel, std::vector<uint8_t>& data) {
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numberOfReceivedBytes += data.size();
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size_t sequenceNumber = data[0];
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printf("L2CAP read %d bytes w/ sequence number %d", data.size(), sequenceNumber);
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if (sequenceNumber != nextSequenceNumber) {
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printf("(wrong sequence number %d, expected %d)\n", sequenceNumber, nextSequenceNumber);
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} else {
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printf("\n");
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nextSequenceNumber++;
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}
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}
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void onDisconnect(NimBLEL2CAPChannel* channel) {
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printf("L2CAP disconnected\n");
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connected = false;
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}
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};
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extern "C"
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void app_main(void) {
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printf("Starting L2CAP server example [%lu free] [%lu min]\n", esp_get_free_heap_size(), esp_get_minimum_free_heap_size());
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BLEDevice::init("L2CAP-Server");
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BLEDevice::setMTU(BLE_ATT_MTU_MAX);
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auto cocServer = BLEDevice::createL2CAPServer();
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auto l2capChannelCallbacks = new L2CAPChannelCallbacks();
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auto channel = cocServer->createService(L2CAP_CHANNEL, L2CAP_MTU, l2capChannelCallbacks);
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auto server = BLEDevice::createServer();
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server->setCallbacks(new GATTCallbacks());
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auto service = server->createService(SERVICE_UUID);
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auto characteristic = service->createCharacteristic(CHARACTERISTIC_UUID, NIMBLE_PROPERTY::READ);
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characteristic->setValue(L2CAP_CHANNEL);
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service->start();
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auto advertising = BLEDevice::getAdvertising();
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advertising->addServiceUUID(SERVICE_UUID);
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advertising->enableScanResponse(true);
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BLEDevice::startAdvertising();
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printf("Server waiting for connection requests [%lu free] [%lu min]\n", esp_get_free_heap_size(), esp_get_minimum_free_heap_size());
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// Wait until transfer actually starts...
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while (!l2capChannelCallbacks->numberOfReceivedBytes) {
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vTaskDelay(10 / portTICK_PERIOD_MS);
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}
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printf("\n\n\n");
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int numberOfSeconds = 0;
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while (true) {
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vTaskDelay(1000 / portTICK_PERIOD_MS);
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if (!l2capChannelCallbacks->connected) { continue; }
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int bps = l2capChannelCallbacks->numberOfReceivedBytes / ++numberOfSeconds;
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printf("Bandwidth: %d b/sec = %d KB/sec [%lu free] [%lu min]\n", bps, bps / 1024, esp_get_free_heap_size(), esp_get_minimum_free_heap_size());
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}
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}
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