3

I want to set up the Bluetooth on boot so I can connect to it whenever I want with a device which is not trusted by the Raspberry Pi Bluetooth. I set up the Bluetooth on boot on my Raspberry Pi this way. In /etc/rc.local, I added :

sudo bluetoothctl <<EOF
power on
discoverable on
pairable on
EOF

sudo hciconfig hci0 sspmode 0
sudo bt-agent -c NoInputNoOutput -p /root/bluetooth.cfg &

I use a Bluetooth configuration file to secure the Bluetooth connection, more information here

The problem is, after some time (~3 minutes), the discoverable mode is automatically turned OFF and I cannot connect to

Another problem is, after a device connect/disconnect, the discoverable mode is also turned OFF.

Is this possible to keep the discoverable mode ON every time and even if some Bluetooth devices connect/disconnect to the Raspberry ?

Edit: I'm using the Raspberry Pi Model B V1.2

  • Yes, I have spent over 10 hours doing what you are doing and finding what you are finding. I read that Rpi3 BLE (BlueLink or similar) is not well supported. Now I have just installed buster, waiting for Rpi4 (ordered a couple of days ago from a shop in stock) & will try again. BTW, I am using Rpi stretch 9 GUI desktop and installed all BLE stuff I searched. But then I read that BLE config files scattered here and there and some of them crash with each other. ( raspberrypi.stackexchange.com/questions/99017/… ) – tlfong01 Jun 27 at 3:04
  • You think it's because of the RPI Bluetooth chip ? It seems to work fine but, I think that, after 3 minutes, the discoverable mode is automatically shutdown to save power. I will soon try with the Raspberry Pi Compute Module 3 and the ATWILC3000 chip. I'll keep you informed if this resolve the problem. – Antoine Boré Jun 27 at 3:08
  • No, I am not saying the hardware, ie, BLE chip is problematic. It is the BLE software drivers that are buggy, or not up to date. Rpi 4 has BT5, so I hope they have a less buggy version. A couple of years ago, I also played with Blue Tooth serial modules, and I also found the BT connections not reliable, with frequent disconnections and need to annoyingly hardware reset. I did try over 10 modules (HC/HM 04/05/10 etc) then. This time I also order "improved" version of BLE 4.0 but not yest tried. Hope you have luck with CM3 and the other BT chip (built into CM3, not an USB module?) . – tlfong01 Jun 27 at 3:19
  • I hope so... I only have to send/receive a small amount of data. Indeed, I want to use the Bluetooth connection so the user can enable the hostapd.service without access to the Raspberry Pi. The solution may be to write a small script ? The CM3 has no built-in Wi-Fi/BT, so the ATWILC3000 is an external serial module. – Antoine Boré Jun 27 at 3:27
2

I continued my research and found an answer that works for me. There is a DiscoverableTimeout on /etc/bluetooth/main.conf which is, by default, set to 300s.

I just add DiscoverableTimeout = 0 on this configuration files.

  • How nice. So you have solved the Blue Tooth problem that have been disturbing so many newbies for a long time. – tlfong01 Jun 27 at 6:14

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