hcitool lescan shows I/O error

Question

I\'m trying to do a lescan using hcitool on the raspberry pi.

The command prints out

Set scan parameters failed: Input/output error. 

Answer 1

I had the same error with hcitool, while bluetoothctl worked just fine. Then I ran across this article stating that all "tools using raw socket shall be considered deprecated" (hcitool, hcicfg, etc.).

So maybe just open bluetoothctl and issue a scan on command.

Answer 2

I have removed Bluez and then I just installed it again, and it worked for me:

sudo apt remove --purge bluez bluez-* -y


apt install bluez

And then

hcitool lescan 

That should be enough.

Answer 3

What worked for me though is opening up the Bluetooth settings on my Ubuntu and manually removing the unused devices. Immediately lescan started working.

Answer 4

I am using Version 5.53 I have two Bluetooth devices (hic0 and hic1) I tried all kinds of ways to to reset the devices ... The only way that worked was to physically unplug and re-insert the hic1 dongle. This is the one that supports ble. Then it works until I reboot. I really wish there was a pure software solution way to do this.

Answer 5

Upgrading to bluez v5.43 fixed this for me.

To upgrade to the newest bluez, you need to do a "manual" installation (not apt-get), downloading from the bluez website. I recommend this video walkthrough if you are new installing packages or need help.

After installing the latest bluez, I had to run a couple commands before it worked.

1. systemctl daemon-reload : Restarts the system daemon.

2. sudo service bluetooth restart : Restarts the Bluetooth service.

3. sudo hciconfig hci0 up : This was needed for my Raspberry Pi 3, with the built-in BT found at hci0.

After these commands, sudo hcitool lescan and its variants all seem to work.

Answer 6

It is possible, that HCI is currently in use. In my case I must stop Node-Red and it works. So take care, that the HCI isn't in use.

Restart the HCI is a way, to solve the problem temporarily, but it doesn't solve the problem right.