Setting up IPv6 over BLE using nRF52 Series and RIOT OS

This tutorial shows you how to get started with RIOT OS on nRF52832 using IPv6 over BLE communication.

To fully understand this tutorial you will need to have minimum knowledge of Linux environment and shell. An nRF52 Development Kit and Bluetooth 4.0-compatible hardware are required to run the examples.

This tutorial should cover everything to get you started.

Introduction

From https://riot-os.org:

"RIOT powers the Internet of Things like Linux powers the Internet. RIOT is a free, open source operating system developed by a grassroots community gathering companies, academia, and hobbyists, distributed all around the world."

RIOT is a powerful open-source operating system for small MCUs like the nRF52832. Being designed from the ground up for IoT applications, it offers a fully pre-emptible micro-kernel, a nice API and extensive networking capabilities.

For more information, check out https://github.com/RIOT-OS/RIOT/wiki/Introduction

1.) Installing the necessary tools

Throughout the rest of the tutorial we’ll assume that we’re using Ubuntu 16.04 Linux distribution. In order to compile for the nRF52 DK platform, you'll need the following tools:

a) Segger JLink Software for Linux (https://www.segger.com/jlink-software.html)

Download and install “Software and documentation pack” using a deb package appropriate for your machine (32bit or 64bit). In order to use the nRF52 DK as a regular Linux user, edit (using sudo) the /etc/udev/rules.d/99-jlink.rules file and replace the ATTR keyword with ATTRS.

b) The remaining tools can be installed using Ubuntu’s package manager:

sudo apt-get install gcc-arm-none-eabi gdb-arm-none-eabi \
    make unzip git \
    python python-serial \
    bluez libcap-ng0

c) Clone the RIOT OS repository:

cd $HOME
git clone https://github.com/RIOT-OS/RIOT

d) Find out your nrf52dk's serial tty

Your nrf52dk will get a serial device file like /dev/ttyACM0. Depending on how many USB ACM serial devices you have in your computer, it might get a different number than "0".

In order to find out the correct device file, powercycle the nrf52dk using it's power switch, then check the output of "dmesg".

Example:

kaspar@ubuntu:~/RIOT$ dmesg | grep 'cdc_acm.*USB ACM device' | tail
[25398.308837] cdc_acm 1-1:1.0: ttyACM0: USB ACM device
[26152.729879] cdc_acm 1-1:1.0: ttyACM0: USB ACM device
kaspar@ubuntu:~/RIOT$

In this example, the nrf52dk got "/dev/ttyACM0", note that down.

2.) Getting started with Hello World

Try RIOT's hello world application:

cd $(HOME)/RIOT/examples/hello-world
BOARD=nrf52dk PORT=<your-tty-device> make clean all flash term -j4

This command should compile the hello-world example, flash it on the board, reset the nrf52dk and start a terminal showing the output.

3.) Setting up an IPv6 connection

Let's try RIOT's CoAP server example and access it from Linux.

First, compile & flash the example:

cd $(HOME)/RIOT/examples/microcoap-example
BOARD=nrf52dk PORT=<your-tty-device> make clean all flash term -j4

As soon as the board has reset after the flashing procedure, it will start advertising itself over BLE. It should also show which address it has auto configured:

[..]
2016-07-12 20:12:45,883 - INFO # Connect to serial port /dev/ttyACM0
Welcome to pyterm!
Type '/exit' to exit.
2016-07-12 20:12:46,890 - INFO # main(): This is RIOT! (Version: 2016.07-devel-393-g8096-booze-nordic_softdevice)
2016-07-12 20:12:46,891 - INFO # RIOT microcoap example application
2016-07-12 20:12:46,892 - INFO # Waiting for address autoconfiguration...
2016-07-12 20:12:49,144 - INFO # Configured network interfaces:
2016-07-12 20:12:49,146 - INFO # Iface  6
2016-07-12 20:12:49,151 - INFO #            Long HWaddr: 02:4c:86:ff:fe:12:d1:0f
2016-07-12 20:12:49,153 - INFO #
2016-07-12 20:12:49,158 - INFO #            MTU:1280  HL:64  6LO  RTR  RTR_ADV  IPHC
2016-07-12 20:12:49,164 - INFO #            Source address length: 8
2016-07-12 20:12:49,165 - INFO #            Link type: wireless
2016-07-12 20:12:49,168 - INFO #            inet6 addr: ff02::1/128  scope: local [multicast]
2016-07-12 20:12:49,173 - INFO #            inet6 addr: fe80::24c:86ff:fe12:d10f/64  scope: local
2016-07-12 20:12:49,179 - INFO #            inet6 addr: ff02::2/128  scope: local [multicast]
2016-07-12 20:12:49,183 - INFO #
2016-07-12 20:12:49,184 - INFO # Waiting for incoming UDP packet...

The node has the link-local address "fe80::24c:86ff:fe12:d10f". Save it for later.

Now open another terminal in order to set up the bluetooth connection.

Then make sure your bluetooth dongle has been recognized:

kaspar@ubuntu:~/RIOT$ hciconfig
hci0:   Type: BR/EDR  Bus: USB
        BD Address: 00:1A:7D:DA:71:14  ACL MTU: 310:10  SCO MTU: 64:8
        UP RUNNING
        RX bytes:640 acl:0 sco:0 events:41 errors:0
        TX bytes:1751 acl:0 sco:0 commands:41 errors:0

kaspar@ubuntu:~/RIOT$

Reset the bluetooth dongle:

sudo hciconfig hci0 reset

Now look for the advertisements using "hcitool":

kaspar@ubuntu:~/RIOT$ sudo hcitool lescan
LE Scan ...
00:4C:86:12:D1:0F RIOT BLE
00:4C:86:12:D1:0F (unknown)
00:4C:86:12:D1:0F RIOT BLE
00:4C:86:12:D1:0F (unknown)
00:4C:86:12:D1:0F RIOT BLE
00:4C:86:12:D1:0F (unknown)
00:4C:86:12:D1:0F RIOT BLE
00:4C:86:12:D1:0F (unknown)
^Ckaspar@ubuntu:~/RIOT$

The tool will not exit itself, but you can exit it using CTRL-C. In the example above, the advertising node was found and it has the Bluetooth address "00:4C:86:12:D1:0F". Copy & paste that somewhere, you'll need that later.

Before we can connect to the device, we need to load and enable the bluetooth_6lowpan kernel module:

kaspar@ubuntu:~/RIOT$ sudo modprobe bluetooth_6lowpan
kaspar@ubuntu:~/RIOT$ echo 1 | sudo tee /sys/kernel/debug/bluetooth/6lowpan_enable

Finally, we can make the connection by running the following command (replace 00:AA:BB:CC:DD:EE with your device’s Bluetooth address):

echo "connect 00:AA:BB:CC:DD:EE 1" | sudo tee /sys/kernel/debug/bluetooth/6lowpan_control

My BLE dongle starts blinking at that point.

Confirm that the BLE interface has been created:

ifconfig bt0

This should show some details.

Now try pinging the node using the link-local address from above, appended with "%" and the bluetooth device name:

ping6 fe80::24c:86ff:fe12:d10f%bt0

If you get ping replies, everything worked so far and your Linux box has IPv6 link-local connectivity towards the nrf52dk.

In theory, this is enough in order to query the nrf52dk using a CoAP client, but unfortunately Firefox cannot access link-local addresses, so in order to use that, we have to configure the nrf52dk with a routable address.

4.) Distributing a routable address

In Linux, this is done by using the Router Advertisement Daemon (RADVD). To configure RADVD, create a /etc/radvd.conf file (as root) and edit it, so that it has the following content:

interface bt0
{
    AdvSendAdvert on;
    prefix 2001:db8::/64
    {
        AdvOnLink off;
        AdvAutonomous on;
        AdvRouterAddr on;
    };
};

Set an address in the subnet for the linux box, enable forwarding and restart radvd:

sudo ip address add 2001:db8::1/64 dev bt0
echo 1 | sudo tee /proc/sys/net/ipv6/conf/all/forwarding
sudo service radvd restart

If successful, all devices connected to the host will receive a routable 2001:db8::/64 prefix. This can be verified by sending an echo request to the full address. The nrf52dk will use the same suffix as for it's link-local address, but with the new prefix instead. So replace "fe80::" with "2001:db8::" and again try to ping:

ping6 2001:db8::24c:86ff:fe12:d10f

Again, you should see some ping replies.

5.) Using Mozilla Firefox as a CoAP client

Once the connection has been established, we can finally play with it. For this you can use Mozilla Firefox with Copper plug-in. You can simply install the plug-in using Firefox’s extensions menu. The plug-in kicks in automatically whenever you enter a URI that uses the coap:// scheme.

In order to use an IPv6 address, it has to be enclosed in "[" and "]". For example with my IP address, the URI would be:

coap://[2001:db8::24c:86ff:fe12:d10f]

After this, a screen similar to the one show in the Figure below will appear.

![image description](/cfs-file/__key/communityserver-blogs-components-weblogfiles/00-00-00-00-04-DZ-981/7041.nrf52dk_5F00_coap.png)

The RIOT example is very basic and, apart from "/.well-known/core", only serves "/riot/board" which returns the board's name as plain text, in your case probably "nrf52dk".

If you made it this far, congratulations! You've successfully set up RIOT with BLE/6lowpan/UDP/CoAP and can access it from you Linux box!

6.) Troubleshooting

Sometimes, the SoftDevice doesn't get flashed correctly, leading to a board that doesn't boot at all. Use "nrfjprog" (available as Nordic download) to recover the board in that case.

Anonymous
  • Robert H. Where is this file "Makefile.include.cortexm_common"? In the RIOT directory?

  • I found part of the reason why a "nrfjprog --family NRF52 --recover" is needed when switching from helloworld example to microcoap_server one:

    microcoap_server needs softdevice.hex to be flashed before. Softdevice.hex is checking the content of address 0x2000: if 0xFFFFFFFF is present, then it jumps to the application(microcoap_server in our case). If different, it will stay in an infinite loop at 0x438.

    Once helloworld example is flashed, the value at 0x2000 is different than 0xFFFFFFFF. The flashing procedure of microcoap_server is not ensuring that the content at this address is erased. Doing the "nrfjprog --family NRF52 --recover" ensure the value at this address is reset to 0xFFFFFFFF.

    I don't know why softdevice.hex is checking this, not sure if anyone knows here.

    Also, I think the microcoap_server flashing should be fixed to ensure this is done. I can do it manually but I have not found a good way of doing it cleanly yet using the JLINK_PRE_FLASH variable for instance: I need to add an erase in the burn.seg file before doing the loadfile for the softdevice.hex.

    Anyone having a suggestion ?

    Thanks.

  • What might be wrong if after following all the steps I am not able to ping routable address but device responses to local link address pings?

  • I have spent some time debugging this and trying to get it work. The issue was in the build process. In the current RIOT-OS Top of Tree, the variable "LINKER_SCRIPT" is not being used. Here's the git diff that will allow you to get the example to function:

    diff --git a/cpu/Makefile.include.cortexm_common b/cpu/Makefile.include.cortexm_common
    index 74b2327..be16d02 100644
    --- a/cpu/Makefile.include.cortexm_common
    +++ b/cpu/Makefile.include.cortexm_common
    @@ -16,7 +16,12 @@ export CFLAGS += $(CFLAGS_CPU) $(CFLAGS_LINK) $(CFLAGS_DBG) $(CFLAGS_OPT)
     
     export ASFLAGS += $(CFLAGS_CPU) $(CFLAGS_DBG)
     export LINKFLAGS += -L$(RIOTCPU)/$(CPU)/ldscripts -L$(RIOTCPU)/cortexm_common/ldscripts
    -export LINKFLAGS += -T$(RIOTCPU)/$(CPU)/ldscripts/$(CPU_MODEL).ld -Wl,--fatal-warnings
    +ifneq (,$(LINKER_SCRIPT))
    +export LINKFLAGS += -T$(LINKER_SCRIPT)
    +else
    +export LINKFLAGS += -T$(RIOTCPU)/$(CPU)/ldscripts/$(CPU_MODEL).ld 
    +endif
    +export LINKFLAGS += -Wl,--fatal-warnings
     export LINKFLAGS += $(CFLAGS_CPU) $(CFLAGS_DBG) $(CFLAGS_OPT) -static -lgcc -nostartfiles
     export LINKFLAGS += -Wl,--gc-sections
    
  • I'm having a similar issue. The hello world example worked fine, but when I flash the microap_server example, it fails to print anything to terminal 1. If I use JLinkExe to halt execution and try to single step, I get J-Link>s 0000041C: FE E7 B #-0x04. Using the single step command again will provide the same output. It seems like it may be a hardfault.