* companion radio for RAK (USB) now fixed. (thanks to Bernd Giesecke)

* experimental NRF52 impl of SerialBLEInterface, and experimental RAK BLE companion radio target

src/helpers/nrf52/SerialBLEInterface.cpp

@@ -0,0 +1,149 @@
+#include "SerialBLEInterface.h"
+
+void SerialBLEInterface::begin(const char* device_name, uint32_t pin_code) {
+  _pin_code = pin_code;
+
+  Bluefruit.begin();
+  Bluefruit.setTxPower(4);    // Check bluefruit.h for supported values
+
+  // To be consistent OTA DFU should be added first if it exists
+  //bledfu.begin();
+}
+
+void SerialBLEInterface::startAdv() {
+  // Advertising packet
+  Bluefruit.Advertising.addFlags(BLE_GAP_ADV_FLAGS_LE_ONLY_GENERAL_DISC_MODE);
+  Bluefruit.Advertising.addTxPower();
+  
+  // Include the BLE UART (AKA 'NUS') 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 
+}
+
+// ---------- public methods
+
+void SerialBLEInterface::enable() { 
+  if (_isEnabled) return;
+
+  _isEnabled = true;
+  clearBuffers();
+
+  // Configure and start the BLE Uart service
+  bleuart.begin();
+
+  // Start advertising
+  startAdv();
+
+  checkAdvRestart = false;
+}
+
+void SerialBLEInterface::disable() {
+  _isEnabled = false;
+
+  BLE_DEBUG_PRINTLN("SerialBLEInterface::disable");
+
+  Bluefruit.Advertising.stop();
+
+  oldDeviceConnected = deviceConnected = false;
+  checkAdvRestart = false;
+}
+
+size_t SerialBLEInterface::writeFrame(const uint8_t src[], size_t len) {
+  if (len > MAX_FRAME_SIZE) {
+    BLE_DEBUG_PRINTLN("writeFrame(), frame too big, len=%d", len);
+    return 0;
+  }
+
+  if (deviceConnected && len > 0) {
+    if (send_queue_len >= FRAME_QUEUE_SIZE) {
+      BLE_DEBUG_PRINTLN("writeFrame(), send_queue is full!");
+      return 0;
+    }
+
+    send_queue[send_queue_len].len = len;  // add to send queue
+    memcpy(send_queue[send_queue_len].buf, src, len);
+    send_queue_len++;
+
+    return len;
+  }
+  return 0;
+}
+
+#define  BLE_WRITE_MIN_INTERVAL   20
+
+bool SerialBLEInterface::isWriteBusy() const {
+  return millis() < _last_write + BLE_WRITE_MIN_INTERVAL;   // still too soon to start another write?
+}
+
+size_t SerialBLEInterface::checkRecvFrame(uint8_t dest[]) {
+  if (send_queue_len > 0   // first, check send queue
+    && millis() >= _last_write + BLE_WRITE_MIN_INTERVAL    // space the writes apart
+  ) {
+    _last_write = millis();
+    bleuart.write(send_queue[0].buf, send_queue[0].len);
+    BLE_DEBUG_PRINTLN("writeBytes: sz=%d, hdr=%d", (uint32_t)send_queue[0].len, (uint32_t) send_queue[0].buf[0]);
+
+    send_queue_len--;
+    for (int i = 0; i < send_queue_len; i++) {   // delete top item from queue
+      send_queue[i] = send_queue[i + 1];
+    }
+  } else {
+    int len = bleuart.available();
+    if (len > 0) {
+      bleuart.readBytes(dest, len);
+      BLE_DEBUG_PRINTLN("readBytes: sz=%d, hdr=%d", len, (uint32_t) dest[0]);
+      return len;
+    }
+  }
+
+  if (Bluefruit.connected() == 0)  deviceConnected = false;
+
+  if (deviceConnected != oldDeviceConnected) {
+    if (!deviceConnected) {    // disconnecting
+      clearBuffers();
+
+      BLE_DEBUG_PRINTLN("SerialBLEInterface -> disconnecting...");
+      delay(500); // give the bluetooth stack the chance to get things ready
+
+      checkAdvRestart = true;
+    } else {
+      BLE_DEBUG_PRINTLN("SerialBLEInterface -> stopping advertising");
+      BLE_DEBUG_PRINTLN("SerialBLEInterface -> connecting...");
+      // connecting
+      // do stuff here on connecting
+      Bluefruit.Advertising.stop();
+      checkAdvRestart = false;
+    }
+    oldDeviceConnected = deviceConnected;
+  }
+
+  if (checkAdvRestart) {
+    if (Bluefruit.connected() == 0) {
+      BLE_DEBUG_PRINTLN("SerialBLEInterface -> re-starting advertising");
+      startAdv();
+    }
+    checkAdvRestart = false;
+  }
+  return 0;
+}
+
+bool SerialBLEInterface::isConnected() const {
+  return deviceConnected;  //pServer != NULL && pServer->getConnectedCount() > 0;
+}