• NUCLEO-F429ZI + X-NUCLEO-IDS01A4

Note, in order to run this border router application on the NUCLEO_F429ZI development board you need to perform the following HW modifications on it:

• Open solder bridge SB121
• Close solder bridge SB122

Furthermore, the RF expansion board X-NUCLEO-IDS01A4 requires these HW modifications:

• Unmount resistor R4
• Mount resistor R7

This document describes how to configure, compile, and run this 6LoWPAN border router application on a STM32 Nucleo development board, especially the NUCLEO-F429ZI, together with the X-NUCLEO-IDS01A4 Sub-1 GHz RF expansion board (a.k.a. Spirit1).

Note: This Border Router does not support Thread.

Border router is a network gateway between a wireless 6LoWPAN mesh network and a backhaul network. It controls and relays traffic between the two networks. In a typical setup, a 6LoWPAN border router is connected to another router in the backhaul network (over Ethernet or a serial line) which in turn forwards traffic to/from the internet or a private company LAN, for instance.

The STM32 Nucleo border router application consists of 4 software components as shown in the image below:

• Nanostack Border Router is the core IPv6 gateway logic and provides the mesh network functionality.
• Spirit1 RF driver is the driver for the STM Spirit1 wireless 6LoWPAN expansion boards.
• Ethernet driver is the Ethernet driver for the STM32 Nucleo development board.
• SLIP driver is a generic Serial Line Internet Protocol version 6 (SLIPv6) driver for mbedOS boards.

• Two STM32 Nucleo development boards (currently only NUCLEO-F429ZI boards are supported), one for the border router application and another one for the 6LoWPAN mbed client application.
• Two STM Spirit1 Sub-1 GHz RF expansion boards X-NUCLEO-IDS01A4 for wireless 6LoWPAN mesh connectivity.
• Two micro-USB cables to connect the development boards to a PC for debugging and power.
• An Ethernet cable to connect the development board to a backhaul network.

• mbed-cli command line interface.
• A compiler. Use one of the following:
  • GCC ARM Embedded.
  • ARM Compiler. (Requires license)
• mbed account.
• A GitHub account.

• PuTTY for serial terminal emulation, see serial connection settings.
• Wireshark for packet inspection and network debugging.
• mbed Windows serial port driver, a serial driver for Windows to enable serial connections.

To configure the STM32 Nucleo border router you need to make changes in the application configuration file mbed_app.json in the root directory of the source tree. For the complete list of configuration options, refer to the Nanostack Border Router documentation.

    "config": {
        "heap-size": {
             "help": "The amount of static RAM to reserve for nsdynmemlib heap",
             "value": 50000
        },
        "debug-trace": "false",
        "trace-baud-rate": "115200",
        "backhaul-driver": "ETH",
        "backhaul-mac-src": "BOARD",
        "backhaul-mac": "{0x02, 0x00, 0x00, 0x00, 0x00, 0x01}"
    }

The STM32 Nucleo border router application can be connected to a backhaul network. This enables you to connect the devices in a 6LoWPAN mesh network to the internet or a private LAN. Currently, the application supports SLIP (IPv6 encapsulation over a serial line) and Ethernet backhaul connectivity.

You can select your preferred option through the mbed_app.json file (field backhaul-driver in the config section). Value SLIP includes the SLIP driver, while the value ETH compiles the STM32 Nucleo border router application with Ethernet backhaul support. You can define the MAC address on the backhaul interface manually (field backhaul-mac-src value CONFIG). Alternatively, you can use the MAC address provided by the development board (field backhaul-mac-src value BOARD). By default, the backhaul driver is set to be ETH and the MAC address source is BOARD.

You can also set the bakchaul bootstrap mode (field backhaul-bootstrap-mode). By default, the bootstrap mode is set to be NET_IPV6_BOOTSTRAP_AUTONOMOUS. With autonomous mode, the border router learns the prefix information automatically from an IPv6 gateway in the ethernet/SLIP segment. Optionally, you can set the bootsrap mode to be NET_IPV6_BOOTSTRAP_STATIC which enables you to set up a manual configuration of backhaul-prefix and default-route.

If you use static bootstrap mode, you need to configure a default route on the backhaul interface to properly forward packets between the backhaul and the 6LoWPAN mesh network. In addition to this, you need to set a backhaul prefix. Static mode creates a site-local IPv6 network from where packets cannot be routed outside.

For more details on how to set the backhaul prefix and default route, refer to the Nanostack Border Router documentation.

When using the autonomous mode, you can set the prefix-from-backhaul option in the mbed_app.jsonfile to true to use the same bakchaul prefix on the mesh network side as well. This allows for the mesh nodes to be directly connectable from the outside of the mesh network.

####Note on the SLIP backhaul driver

You need to use the UART1 serial line of the K64F board with the SLIP driver. See the pins section in the project's yotta configuration. To use a different UART line, replace the SERIAL_TX and SERIAL_RX values with correct TX/RX pin names. If you wish to use hardware flow control, set the configuration field slip_hw_flow_control``to true. By default, it is set to false`. Before using hardware flow control, make sure that the other end of your SLIP interface can handle flow control.

For the pin names of your desired UART line, refer to the STM32 Nucleo documentation.

Example mbed_app.json configuration for the SLIP driver:

    "config": {
  	    "SERIAL_TX": "SERIAL_TX",
    	"SERIAL_RX": "SERIAL_RX",
    	"SERIAL_CTS": "PD_11",
    	"SERIAL_RTS": "PD_12"
    }

By default the application uses the Spirit1 RF driver. You can alternatively use the Atmel AT86RF233/212B RF or the FRDM-MCR20A shield also. The used RF driver is set in the mbed_app.json file.

To use the STM Spirit1 radio, use following:

    "config": {
        "radio-type":{
            "help": "options are SPIRIT1, ATMEL, MCR20",
            "value": "SPIRIT1"
        }
    }

To use the Atmel radio, use following:

    "config": {
        "radio-type":{
            "help": "options are SPIRIT1, ATMEL, MCR20",
            "value": "ATMEL"
        }
    }

To use the NXP radio, use following:

    "config": {
        "radio-type":{
            "help": "options are SPIRIT1, ATMEL, MCR20",
            "value": "MCR20"
        }
    }

In case you have choosen the STM Spirit1 Sub-1 GHz RF expansion board X-NUCLEO-IDS01A4, you need also to configure its MAC address in the mbed_app.json file, e.g.:

    "target_overrides": {
        "*": {
            "spirit1.mac-address": "{0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7}"
        },
    }

Note, that this MAC address must be unique within the 6LoWPAN mesh network.

After changing the radio, you need to recompile the application.

1. Install mbed-cli
2. Clone the repository: git clone https://github.com/ARMmbed/stm32-border-router.git
3. Change directory to stm32-border-router
4. Modify the mbed_app.json file to reflect to your network setup
5. Deploy required libraries: mbed deploy
6. Generate mbed application root: mbed new .
7. Build: mbed compile -m NUCLEO_F429ZI -t GCC_ARM

The binary will be generated into BUILD/NUCLEO_F429ZI/GCC_ARM/stm32-border-router.bin.

1. Find the binary file stm32-border-router.bin in the folder BUILD/NUCLEO_F429ZI/GCC_ARM/.
2. Copy the binary to the USB mass storage root of the STM32 Nucleo development board. It is automatically flashed to the target MCU. When the flashing is complete, the board restarts itself. Press the Reset button of the development board if it does not restart automatically.
3. The program begins execution.
4. Open the serial connection, for example PuTTY.

Serial connection settings for the border router application are as follows:

* Baud-rate = 115200
* Data bits = 8
* Stop bits = 1
* flow control = xon/xoff

If there is no input from the serial terminal, press the Reset button of the development board.

In the PuTTY main screen, save the session and click Open. This opens a console window showing debug messages from the application. If the console screen is blank, you may need to press the Reset button of the board to see the debug information. The prints for the border router look something like this in the console:

[INFO][app ]: Starting NUCLEO_F429ZI border router...
[INFO][app ]: Using ETH backhaul driver...
[ERR ][brro]: Backhaul interface down failed
[INFO][Eth ]: Ethernet cable connected.
[INFO][addr]: Tentative Address added to IF 2: fe80::280:e1ff:fe3e:42
[INFO][addr]: DAD passed on IF 2: fe80::280:e1ff:fe3e:42
[INFO][addr]: Tentative Address added to IF 2: 2001:470:1f13:280:280:e1ff:fe3e:42
[INFO][addr]: DAD passed on IF 2: 2001:470:1f13:280:280:e1ff:fe3e:42
[INFO][brro]: Backhaul bootstrap ready, IPv6 = 2001:470:1f13:280:280:e1ff:fe3e:42
[INFO][brro]: Backhaul interface addresses:
[INFO][brro]:    [0] fe80::280:e1ff:fe3e:42
[INFO][brro]:    [1] 2001:470:1f13:280:280:e1ff:fe3e:42
[INFO][addr]: Address added to IF 1: fe80::ff:fe00:face
[INFO][br  ]: BR nwk base ready for start
[INFO][br  ]: Refresh Contexts
[INFO][br  ]: Refresh Prefixs
[INFO][addr]: Address added to IF 1: 2001:470:1f13:280:0:ff:fe00:face
[INFO][addr]: Address added to IF 1: fe80::f2f1:f2f3:f4f5:f6f7
[INFO][brro]: RF bootstrap ready, IPv6 = 2001:470:1f13:280:0:ff:fe00:face
[INFO][brro]: RF interface addresses:
[INFO][brro]:    [0] fe80::ff:fe00:face
[INFO][brro]:    [1] fe80::f2f1:f2f3:f4f5:f6f7
[INFO][brro]:    [2] 2001:470:1f13:280:0:ff:fe00:face
[INFO][brro]: 6LoWPAN Border Router Bootstrap Complete.