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Bluetooth: IPSP Sample

Overview

Application demonstrating the IPSP (Internet Protocol Support Profile) Node role. IPSP is the Bluetooth profile that underneath utilizes 6LoWPAN, i.e. gives you IPv6 connectivity over BLE.

Building and Running

This sample can be found under samples/bluetooth/ipsp in the Zephyr tree. Sample can be built and executed for the nRF52840 DK NRF52840 as follows:

west build -b nrf52840dk_nrf52840 samples/bluetooth/ipsp
west flash

To build a debug version, with logging and shell support, use the config file prj_dbg.conf:

west build -b nrf52840dk_nrf52840 samples/bluetooth/ipsp -- -DCONF_FILE=prj_dbg.conf
west flash

Building and Running for Linux kernels released before 4.12

Note

For hosts using kernels released before 4.12, option CONFIG_NET_L2_BT_ZEP1656 must be selected. For more information, see Zephyr issue #3111.

west build -b nrf52840dk_nrf52840 samples/bluetooth/ipsp -- -DCONF_FILE="prj_zep1656.conf"
west flash

Testing with a Linux host

Make sure the Linux kernel has been built with Bluetooth 6LoWPAN module (CONFIG_BT_6LOWPAN=y) then proceed to enable it with with the following commands (as root):

# modprobe bluetooth_6lowpan
# echo 1 > /sys/kernel/debug/bluetooth/6lowpan_enable

If you connected your board to a UART console, you will see an output similar to (may vary slightly by application and Zephyr versions):

[bt] [WRN] set_static_addr: Using temporary static random address
[bt] [INF] show_dev_info: Identity: cb:af:14:57:d8:6e (random)
[bt] [INF] show_dev_info: HCI: version 5.0 (0x09) revision 0x0000, manufacturer 0xffff
[bt] [INF] show_dev_info: LMP: version 5.0 (0x09) subver 0xffff
[bt] [WRN] bt_pub_key_gen: ECC HCI commands not available
[ipsp] [INF] init_app: Run IPSP sample
[ipsp] [INF] listen: Starting to wait

The output above shows the BLE address assigned to your board for the current session; the address will be different on subsequent sessions.

Alternatively, you may scan for your board on the host. The modern way to do that is using bluetoothctl utility (included in the recent versions of BlueZ package) and its scan on command:

$ bluetoothctl
[NEW] Controller A3:24:97:EB:D6:23 ubuntu-0 [default]
[NEW] Device D7:5C:D6:18:14:87 Zephyr
[NEW] Device E1:E7:F9:56:EC:06 Zephyr
[NEW] Device C8:12:C5:08:86:E1 Zephyr
[bluetooth]# scan on
Discovery started
[NEW] Device DC:98:FB:22:CA:3A Zephyr

When started, bluetoothctl shows all BLE (and likely, BT/EDR) devices it knows about. As discussed above, the IPSP uses static random addresses, so entries for previously connected devices, as shown above, can accumulate and become stale. You need to be extra careful to find an entry for the active address. The best approach may be to reset your board after issuing scan on command. This way it will reinitialize with the BLE address which will be discovered after the command.

As an alternative to bluetoothctl, you can use the legacy hcitool utility which talks directly to hardware and always shows fresh scan results:

$ sudo hcitool lescan
LE Scan ...
CB:AF:14:57:D8:6E (unknown)
CB:AF:14:57:D8:6E Test IPSP node

After you have found the board’s BLE address, connect to the board (as root):

# echo "connect <bdaddr> <type>" > /sys/kernel/debug/bluetooth/6lowpan_control

Where <bdaddr> is the BLE address and <type> is BLE address type: 1 for public address and 2 for random address. As you can see from the IPSP sample output above, it uses a static random address. So, with the sample output above, the command will be:

# echo "connect CB:AF:14:57:D8:6E 2" > /sys/kernel/debug/bluetooth/6lowpan_control

Once connected a dedicated interface will be created, usually bt0. You can verify this with the following command:

# ifconfig
bt0       Link encap:UNSPEC  HWaddr F8-2F-A8-FF-FE-EB-6D-8C-00-00-00-00-00-00-00-00
          inet6 addr: fe80::fa2f:a8ff:feeb:6d8c/64 Scope:Link
          UP POINTOPOINT RUNNING MULTICAST  MTU:1280  Metric:1
          RX packets:2 errors:0 dropped:3 overruns:0 frame:0
          TX packets:6 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:92 (92.0 B)  TX bytes:233 (233.0 B)

As can be seen from the output, only a link-local IPv6 address was assigned to the interface.

At this point, you can test IPv6 connectivity (and discover your board’s IPv6 address) by pinging “All local-link nodes” IPv6 address:

# ping6 -I bt0 ff02::1
PING ff02::1(ff02::1) from fe80::fa54:a8ff:feeb:218f bt0: 56 data bytes
64 bytes from fe80::fa54:a8ff:feeb:218f: icmp_seq=1 ttl=64 time=0.088 ms
64 bytes from fe80::c9af:14ff:fe57:d86e: icmp_seq=1 ttl=64 time=285 ms (DUP!)

For each ping packet, both your host and the BLE board send a reply. You can see the board’s reply marked as (DUP!). You can ping the board directly with:

# ping6 fe80::c9af:14ff:fe57:d86e%bt0
PING fe80::c9af:14ff:fe57:d86e%bt0(fe80::c9af:14ff:fe57:d86e) 56 data bytes
64 bytes from fe80::c9af:14ff:fe57:d86e: icmp_seq=1 ttl=64 time=177 ms
64 bytes from fe80::c9af:14ff:fe57:d86e: icmp_seq=2 ttl=64 time=53.0 ms

Note that the command uses a “scoped IPv6 address”, where the scope is defined by the networking interface, with %bt0 appended in this case. A specification like that is an alternative to passing -I bt0 to ping6 (and works with other networking tools like telnet, nc, curl, etc.)

While we can use a link-local address, it’s not very convenient, as it must be scoped and will change on each run. Instead, the IPSP sample is configured with 2001:db8::1 static address and we’ll configure the host’s interface to access that address by configuring bt0 with the complementary address 2001:db8::2:

# ip address add 2001:db8::2/64 dev bt0

Now we can ping the board’s static address with:

# ping6 2001:db8::1
PING 2001:db8::1(2001:db8::1) 56 data bytes
64 bytes from 2001:db8::1: icmp_seq=1 ttl=64 time=282 ms

The IPSP sample includes builtin echo server for UDP and TCP on a port 4242, which we can test with:

$ telnet 2001:db8::1 4242
Trying 2001:db8::1...
Connected to 2001:db8::1.
Escape character is '^]'.
test
test
test2
test2
^]
telnet> quit
Connection closed.

In the output above, first test line was typed, next was echoed back by the board. Likewise for test2. To quit telnet tool, type Ctrl+], then “quit” at the prompt.

As an alternative to using well-known networking tools above, and also to test both TCP and UDP echo, you can use Zephyr’s helper tool in the GitHub zephyrproject-rtos/net-tools repository:

$ echo-client -i bt0 <ip>