add BluefruitStream wrapper for firmata

Author: hathach

libraries/Firmata/utility/BluefruitStream.h

@@ -0,0 +1,108 @@
+/**************************************************************************/
+/*!
+    @file     BluefruitStream.h
+
+    Wrapper for Adafruit Bluefruit nRF52
+*/
+/**************************************************************************/
+#ifndef BLUEFRUITSTREAM_H_
+#define BLUEFRUITSTREAM_H_
+
+#ifdef ARDUINO_NRF52_ADAFRUIT
+
+#include <bluefruit.h>
+
+class BLEStream : public Stream
+{
+  private:
+    BLEUart     _bleuart;
+    const char* _name;
+    uint16_t    _conn_min, _conn_max;
+
+  public:
+    BLEStream(void);
+
+    void begin(void);
+    bool poll();
+    void setLocalName(const char* str) { _name = str; }
+    void setConnectionInterval(uint16_t min, uint16_t max) { _conn_min = min; _conn_max = max; }
+    void setFlushInterval(int interval) {} // flush interval is handled internally by BLEUart
+
+    // Forward all stream API to bleuart
+    virtual int    available (void)         { return _bleuart.available(); }
+    virtual int    peek      (void)         { return _bleuart.peek();      }
+    virtual int    read      (void)         { return _bleuart.read();      }
+    virtual void   flush     (void)         { return _bleuart.flush();     }
+    virtual size_t write (uint8_t byte)     { return _bleuart.write(byte); }
+
+    virtual size_t write ( const uint8_t *content, size_t len )
+    {
+      return _bleuart.write(content, len);
+    }
+    using Print::write;
+
+//    virtual operator bool();
+};
+
+BLEStream::BLEStream(void)
+{
+  _name = NULL;
+  _conn_min = 9;  // 9*1.25=11.25 ms
+  _conn_max = 16; // 16*1.25=20ms
+}
+
+void BLEStream::begin(void)
+{
+  Bluefruit.begin();
+
+  // set name
+  if (_name) Bluefruit.setName(_name);
+
+  // set connection interval
+  Bluefruit.setConnInterval(_conn_min, _conn_max);
+
+  // Configure and Start BLE Uart Service
+  // Firmata use several small write(1) --> buffering TXD is required to run smoothly
+  // Enable buffering TXD
+  _bleuart.begin();
+  _bleuart.bufferTXD(true);
+
+  /*------------- Advertising -------------*/
+  // Advertising packet
+  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
+  Bluefruit.Advertising.addTxPower();
+
+  // Include bleuart 128-bit uuid
+  Bluefruit.Advertising.addService(_bleuart);
+
+  // Secondary Scan Response packet (optional)
+  // Since there is no room for 'Name' in Advertising packet
+  Bluefruit.ScanResponse.addName();
+
+  /* Start Advertising
+   * - Enable auto advertising if disconnected
+   * - Interval:  fast mode = 20 ms, slow mode = 152.5 ms
+   * - Timeout for fast mode is 30 seconds
+   * - Start(timeout) with timeout = 0 will advertise forever (until connected)
+   *
+   * For recommended advertising interval
+   * https://developer.apple.com/library/content/qa/qa1931/_index.html
+   */
+  Bluefruit.Advertising.restartOnDisconnect(true);
+  Bluefruit.Advertising.setInterval(32, 244);    // in unit of 0.625 ms
+  Bluefruit.Advertising.setFastTimeout(30);      // number of seconds in fast mode
+  Bluefruit.Advertising.start(0);                // 0 = Don't stop advertising after n seconds
+}
+
+/**
+ * Flush is handled by BLEUart internally.
+ * @return true if connected and bleuart notify is enabled
+ */
+bool BLEStream::poll(void)
+{
+  return Bluefruit.connected() && _bleuart.notifyEnabled();
+}
+
+#endif
+
+#endif /* BLUEFRUITSTREAM_H_ */