Got bluetooth talking over a serial port

2026-07-07 00:09:35 +00:00
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+# Bluetooth on the Raspberry Pi Zero W (1 or 2)
+The Zero W series has Bluetooth capability because of the Wifi chip on the board.
+**Warning:  This is a work in progress!!!**
+
+# Reference
+- "Exploring Raspberry Pi" by Derek Molloy pg 537-544
+- [Connecting to a Headless Raspberry Pi using Bluetooth](https://medium.com/@tomw3115/connect-to-a-headless-raspberry-pi-using-bluetooth-0e61c05e1b68)
+- https://github.com/sorah/bluetooth-getty
+- [Use dbus insteadd of sdptool](https://linuxvox.com/blog/bluez-adding-services-attributes-and-profiles-without-sdptool-command/)
+
+# Getting Bluetooth working
+1. Login to the pi via a USB-serial port or monitor-keyboard-mouse.  Configuring bluetooth can sometimes kick you off the wifi.
+1. Tell `rfkill` to unblock bluetooth.  Perhaps this is a security thing?
+```
+sudo rfkill unblock bluetooth
+```
+1. Restart the bluetooth service and check it's status
+```
+sudo systemctl restart bluetooth
+sudo systemctl status bluetooth
+```
+1. Figure out the address using `hcitool`
+```
+hcitool dev
+```
+1. If you have a laptop set to be discoverable, you can check if bluetooth is working
+```
+hcitool scan
+```
+1. You can then query that device for what services it offers
+```
+sdptool browse ADDRESS
+```
+1. Now we want to make the Pi discoverable to our phone, tablet, or laptop
+```
+sudo hciconfig hci0 piscan
+sudo hciconfig hci name RaspberryPi
+```
+1. A Serial Port Profile(SPP) is needed for our serial port
+```
+sudo sdptool add SP
+```
+1. For some reason, we have to put the bluetooth daemon in compatibility mode.  (True as of 2016-2026 --foley).  Find the line with `ExecStart` and put `--compat` at the end
+```
+sudo nano /lib/systemd/system/bluetooth.service
+```
+1. Test the SPP is setup
+
+```
+sudo sdptool browse local
+```
+1. Time to pair it with a device
+```
+sudo bluetoothctl
+discoverable on
+agent on
+pairable on 
+scan on
+```
+and once you have paired it
+```
+discoverable off
+exit
+```
+
+1. If this works, you can install the `bluetooth.services` and `rfcomm.service` files to automate some of this setup.
+```
+sudo cp bluetooth.service /etc/systemd/system/bluetooth.target.wants/.
+sudo cp rfcomm.service /etc/systemd/system/.
+sudo systemctl daemon-reload
+sudo systemctl enable rfcomm
+sudo reboot
+
+```
+
+
+
+# Discussion
+Apparently Bluez's `sdptool` is now depricated and they are telling people to use this new GATT via `busctl` or `dbus-send`. [linuxvox article on depricated sdptool](https://linuxvox.com/blog/bluez-adding-services-attributes-and-profiles-without-sdptool-command/)