Alright, let's get your embedded Linux board set up for SPP (Serial Port Profile) Bluetooth communication with an iPhone. I’ve tackled this exact scenario multiple times with BlueZ, so here’s a step-by-step breakdown that should get you up and running smoothly:

First, make sure your Bluetooth stack is active:

• Check if the Bluetooth service is running: systemctl status bluetooth
• If it’s not running, start it with: systemctl start bluetooth
• Set it to auto-start on boot: systemctl enable bluetooth
• Enable your Bluetooth adapter (replace hci0 if your adapter uses a different ID): hciconfig hci0 up
• Confirm the adapter is in working order: hciconfig (you should see UP RUNNING next to your adapter)

iPhones can only pair with devices that are visible, so tweak these settings:

• Open the main BlueZ config file: nano /etc/bluetooth/main.conf
• Update these parameters:
  • DiscoverableTimeout = 0 (keeps the device permanently discoverable; adjust to a non-zero value if you want auto-disable)
  • PairableTimeout = 0 (allows permanent pairing capability)
  • AutoEnable = true (ensures the adapter turns on automatically)
• Restart the Bluetooth service to apply changes: systemctl restart bluetooth
• Force the adapter into discoverable/pairable mode: hciconfig hci0 piscan

iPhones won’t recognize your device as a serial port unless the SPP service is registered in the Bluetooth service database:

• Add the SPP profile to your local service record:

  sdptool add --channel=1 SP
  

  (Channel 1 is the standard for SPP, but you can use any unused channel between 1-30—just remember the number for later steps)
• Verify the service was added: sdptool browse local
  Look for a Serial Port entry in the output; this confirms the SPP service is visible to nearby devices.

Map the Bluetooth serial port to a system device file so you can interact with it like a regular serial port:

• Bind the RFCOMM device to your adapter and channel:

  rfcomm bind /dev/rfcomm0 hci0 1
  

  (Use the same channel number you set with sdptool)
• Check if the device was created: ls -l /dev/rfcomm0
• To make this binding persistent across reboots, add the command to /etc/rc.local (if your system uses it) or create a simple systemd service.

iPhones sometimes fail to pair due to permission issues—here’s how to resolve that:

• Edit the RFCOMM config file: nano /etc/bluetooth/rfcomm.conf
• Add this section (replace <YOUR_BOARD_MAC> with your adapter’s MAC, found via hciconfig hci0):

  rfcomm0 {
      bind yes;
      device <YOUR_BOARD_MAC>;
      channel 1;
      comment "Embedded SPP Serial Port";
  }
  

• Give your user access to the serial device: usermod -aG dialout <YOUR_USERNAME>
• (Optional) Set a custom pairing PIN by adding PinCode = "1234" to main.conf (replace 1234 with your preferred code)

• Pairing: On your iPhone, open Settings > Bluetooth, find your board’s name (customize it with hciconfig hci0 name "My SPP Board" if needed), and tap to pair. Enter the PIN you set (or default 0000/1234 if you didn’t customize).
• Data Transfers: Use an iPhone app that supports Bluetooth serial (like Serial Bluetooth Terminal). Once connected:
  • On your board, receive data with: cat /dev/rfcomm0
  • Send data to the iPhone with: echo "Hello from Linux!" > /dev/rfcomm0

• If the iPhone can’t find your board: Double-check hciconfig hci0 shows PISCAN mode, and DiscoverableTimeout is set to 0 in main.conf.
• If pairing succeeds but connection fails: Ensure sdptool added the SPP service correctly, and the RFCOMM channel matches the one in the service record.
• If data isn’t sending/receiving: Verify your user has dialout group access, or test with sudo cat /dev/rfcomm0 to rule out permission issues.

内容的提问来源于stack exchange，提问作者Subbu