====== Bluetooth ======

Step by step tutorial how to pair and connect with Bluetooth a device with AGL to a smartphone. This tutorial has been tested with the built-in Bluetooth in Raspberry Pi 3 B/B+ and Raspberry Pi 4. 

Images for Raspberry Pi 4 include [[https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/22508|recipe pi-bluetooth. It provides a script that starts automatically and properly configures BT-HCI.]] The same script is used in Raspbian.

* Verify that the Bluetooth module is detected:

  hciconfig -a
  
**Note:** Check the troubleshooting if the Bluetooth module is NOT detected

* Launch bluetoothctl:

  bluetoothctl

* Power on the Bluetooth controller:

  [bluetooth]# power on

* Enable the agent and set it as default:

  [bluetooth]# agent on
  [bluetooth]# default-agent

* Set the Bluetooth controller as discoverable for 3 minutes and pairable:

  [bluetooth]# discoverable on
  [bluetooth]# pairable on

* Scan for other device to retrieve the smartphone:

  [bluetooth]# scan on

* Find out the MAC address of the smartphone:

  [bluetooth]# devices

* Pair with the smartphone:

  [bluetooth]# pair smartphone_mac_address

* Enter 4 digit PIN if prompted. Enter the same PIN on the smartphone.

  [agent]PIN code: ####

* Allow the service authorization if requested.

  [agent]Authorize service service_uuid (yes/no): yes

* Trust the smartphone:

  [bluetooth]# trust smartphone_mac_address

* Connect to the smartphone:

  [bluetooth]# connect smarphone_mac_address

Verify that the smartphone is successfully connected and display information about it with the following command:

  [bluetooth]# info smarphone_mac_address

The device has been successfully paired with the smartphone and you now can exit bluetoothctrl:

  [bluetooth]# quit
  
==Troubleshooting==

* Start Bluetooth systemd service:

  rfkill unblock bluetooth
  hciconfig hci0 up
  systemctl start bluetooth