Can't find "bt0" on Raspberry Pi 4

[Lin Bencheng]

Hello, Everyone
I am going to develop an IoT project with nRF52840 and Raspberry Pi 4

My idea is exactly the same as this link
https://visualgdb.com/tutorials/arm/nrf51/6lowpan/
I have followed the below links to build BLE 6LoWPAN environment on my Rpi4

• https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v14.2.0%2Fiot_ug_border_router.html
• https://devzone.nordicsemi.com/f/nordic-q-a/26003/rpi3-6lowpan_control-permission-denied

All commands were working fine until echo "connect <mac address of other device> 1" > /sys/kernel/debug/bluetooth/6lowpan_control. As seen from the websites, after this command execution, there should be bt0 interface created. But it is not visible in ifconfig -a.

Also the 6lowpan_control file is empty. But when I try to connect the other device using the command hcitool con after executing the above command, I am able to see the desired connections in the terminal, still no bt0 device available. I have even tried with the command ifconfig bt0 add 2001:db8::1/64 but resulted in the error SIOGIFINDEX: No such device.

How to resolve this problem?

[Jørgen Holmefjord]

Hi,

Which OS are you running on the RPi 4? As far as I know, 6LowPAN support should be enabled by default in Raspbian releases the last few years, no need to build the kernel as described in the docs.

Did you check if a connection was actually established with the device on the address that you passed to 'echo "connect' command? Could you capture a sniffer trace to see what happens on-aur between the RPi and the nRF52840?

Best regards,
Jørgen

[Lin Bencheng]

Thanks for your reply

I am using Raspberry pi OS full (2021.1.21 released).
I tried the old version of Raspberrian OS, But if I install the old version, My RPi 4 doesn't start OS.
Yes, This new OS support 6LowPAN as default.
I can find my nRF52 DK board with this command on RPi 4
hcitool lescan
Then also this command works
echo "connect 00:AA:BB:XX:YY:ZZ 1" > /sys/kernel/debug/bluetooth/6lowpan_control
After this
when I tri this command
ifconfig 
I couldn't find the bt0.
Of course, I created the RAVID configuration file on the etc folder 
  

interface bt0

{

AdvSendAdvert on;

prefix 2001:db8::/64

{

  AdvOnLink off;

  AdvAutonomous on;

  AdvRouterAddr on;

 };

};

As you can see, I couldn't connect to nRF DK 
but can't find bt0 interface
I hope your news
Thanks