Esp32CoreBleTransport.h

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// Transport for the BLE library of arduino-esp32 3.x (BLEDevice / BLEServer /
// BLECharacteristic; 4.x replaced it, see Esp32Ble4Transport.h), which sits on Bluedroid on
// the classic ESP32 and on NimBLE on the S3/C3/C6/H2/P4 variants. One transport, two
// `#if defined(CONFIG_BT_NIMBLE_ROLE_PERIPHERAL)` branches at the callback layer, because the
// two stacks deliver subscriptions differently (Bluedroid: a write to the CCCD descriptor;
// NimBLE: BLECharacteristicCallbacks::onSubscribe) — the 1.x fix in commit 42bad88. Never
// pins a task to a core (1.x commit ca630b9, single-core C3).
//
// notify() returns void in this library on both stacks; a send refused up front arrives as
// BLECharacteristicCallbacks::onStatus(ERROR_GATT, rc) from inside notify(), which this
// transport turns into a synchronous false. On Bluedroid a packet can still be dropped later,
// in the stack's own task, so for the experiment characteristic the transport also waits for
// the stack's confirmation event (see the .cpp). Those are the signals the transfer's retry
// hangs off (plan §3.4). Build with -DPHYPHOX_BLE_ESP32_TRACE to see refused confirmations on
// Serial. poll() is a no-op: the stack runs in its own tasks.
#ifndef PHYPHOX_BLE_TRANSPORT_ESP32COREBLE_H
#define PHYPHOX_BLE_TRANSPORT_ESP32COREBLE_H
 
#include "Transport.h"
 
namespace phyphox {
 
class Esp32CoreBleTransport : public Transport {
public:
    bool begin(const GattLayout& layout, TransportListener& listener) override;
    bool notify(CharId id, const uint8_t* data, uint16_t len) override;
    void setValue(CharId id, const uint8_t* data, uint16_t len) override;
    bool connected() const override;
    uint16_t mtuPayload() const override;
    void requestMtu(uint16_t payload) override;
    void requestConnectionParameters(uint16_t, uint16_t, uint16_t, uint16_t) override;
    void poll() override {}
    bool drivesTransfer() const override { return true; }
    void restartAdvertising() override;
    const char* name() const override { return "ESP32"; }
    static Esp32CoreBleTransport& instance();
private:
    Esp32CoreBleTransport() {}
    // Services are created with an explicit handle count (2 per characteristic + 1 per CCCD),
    // never the library's default of 15 — plan §3.3.
};
 
} // namespace phyphox
 
#endif