Wireless MCU Zephyr Development#

BeaglePlay includes a Texas Instruments CC1352P7 wireless microcontroller (MCU) that can be programmed using the Linux Foundation Zephyr RTOS.

Developing directly in Zephyr will not be ultimately required for end-users who won’t touch the firmware running on the CC1352 on BeaglePlay™ and will instead use the provided wireless functionality. However, it is important for early adopters as well as people looking to extend the functionality of the open source design. If you are one of those people, this is a good place to get started.

Further, BeaglePlay is a reasonable development platform for creating Zephyr-based applications for BeagleConnect Freedom. The same Zephyr development environment setup here is also described for targeting applications on that board.

Install the latest software image for BeaglePlay#

Note

These instructions should be generic for BeaglePlay and other boards and only the specifics of which image was used to test these instructions need be included here moving forward and the detailed instructions can be referenced elsewhere.

You may want to download and install the latest Debian Linux operating system image for BeaglePlay.

Note

These instructions were validated with the BeagleBoard.org Debian image BeaglePlay Debian 11.6 Flasher 2023-03-10.

  1. Load this image to a microSD card using a tool like Etcher.

  2. Insert the microSD card into BeaglePlay.

  3. Power BeaglePlay via the USB-C connector.

  4. Wait for the LEDs to start blinking, then turn off.

  5. Remove power from BeaglePlay.

  6. IMPORTANT Remove microSD card from BeaglePlay.

  7. Apply power to BeaglePlay.

Note

This will flash the CC1352 as well as the eMMC flash on BeaglePlay.

Log into BeaglePlay#

Please either plug in a keyboard, monitor and mouse or ssh into the board. We can point somewhere else for instructions on this. You can also point your web browser to the board to log into the Visual Studio Code IDE environment.

Flash existing IEEE 802.15.4 radio bridge (WPANUSB) firmware#

If you’ve recieved a board fresh from the factory, this is already done and not necessary, unless you want to restore the contents back to the factory condition.

Background#

This WPANUSB application was originally developed for radio devices with a USB interface. The CC1352P7 does not have a USB device, so the application was modified to communicate over a UART serial interface.

For the BeagleConnect Freedom, a USB-to-UART bridge device was used and the USB endpoints were made compatible with the WPANUSB linux driver which we augmented to support this board. To utilize the existing WPANUSB Zephyr application and this Linux driver, we chose to encode our UART traffic with HDLC. This has the advantage of enabing a serial console interface to the Zephyr shell while WPANUSB-specific traffic is directed to other USB endpoints.

For BeaglePlay, the USB-to-UART bridge is not used, but we largely kept the same WPANUSB application, including the HDLC encoding.

Note

Now you know why this WPAN bridge application is called WPANUSB, even though USB isn’t used!

Steps#

  1. Ensure the bcfserial driver isn’t blocking the serial port.

    echo "    fdtoverlays /overlays/k3-am625-beagleplay-bcfserial-no-firmware.dtbo" | sudo tee -a /boot/firmware/extlinux/extlinux.conf
sudo shutdown -r now

    Note

    The default password is temppwd.

  2. Download and flash the WPANUSB Zephyr application firmware onto the CC1352P7 on BeaglePlay from the releases on git.beagleboard.org or distros on www.beagleboard.org/distros.

    debian@BeaglePlay:~$ wget https://files.beagle.cc/file/beagleboard-public-2021/images/zephyr-beagle-cc1352-0.2.2.zip
debian@BeaglePlay:~$ unzip zephyr-beagle-cc1352-0.2.2.zip
debian@BeaglePlay:~$ build/play/cc2538-bsl.py build/play/wpanusb

  3. Ensure the bcfserial driver is set to load.

    sudo sed -e '/bcfserial-no-firmware/ s/^#*/#/' -i /boot/firmware/extlinux/extlinux.conf
sudo shutdown -r now

  4. Verify the the 6LoWPAN network is up.

    debian@BeaglePlay:~$ lsmod | grep bcfserial
bcfserial              24576  0 ①
mac802154              77824  2 wpanusb,bcfserial
debian@BeaglePlay:~$ ifconfig
SoftAp0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.8.1  netmask 255.255.255.0  broadcast 192.168.8.255
        inet6 fe80::3ee4:b0ff:fe7e:b5f7  prefixlen 64  scopeid 0x20<link>
        ether 3c:e4:b0:7e:b5:f7  txqueuelen 1000  (Ethernet)
        RX packets 4046  bytes 576780 (563.2 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4953  bytes 5116336 (4.8 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

docker0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        inet 172.17.0.1  netmask 255.255.0.0  broadcast 172.17.255.255
        ether 02:42:f8:29:41:69  txqueuelen 0  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
        ether f4:84:4c:fc:5d:13  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 246239  bytes 19948296 (19.0 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 246239  bytes 19948296 (19.0 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lowpan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1280 ②
        inet6 fe80::200:0:0:0  prefixlen 64  scopeid 0x20<link> ③
        inet6 2001:db8::2  prefixlen 64  scopeid 0x0<global> ④
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 1000  (UNSPEC)
        RX packets 107947  bytes 6629290 (6.3 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2882  bytes 179511 (175.3 KiB) ⑤
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

usb0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.7.2  netmask 255.255.255.0  broadcast 192.168.7.255
        inet6 fe80::1eba:8cff:fea2:ed6b  prefixlen 64  scopeid 0x20<link>
        ether 1c:ba:8c:a2:ed:6b  txqueuelen 1000  (Ethernet)
        RX packets 9858  bytes 2638440 (2.5 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4155  bytes 1454082 (1.3 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

usb1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.6.2  netmask 255.255.255.0  broadcast 192.168.6.255
        inet6 fe80::1eba:8cff:fea2:ed6d  prefixlen 64  scopeid 0x20<link>
        ether 1c:ba:8c:a2:ed:6d  txqueuelen 1000  (Ethernet)
        RX packets 469614  bytes 35385636 (33.7 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 365548  bytes 66523708 (63.4 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.161  netmask 255.255.255.0  broadcast 192.168.0.255
        inet6 fe80::3ee4:b0ff:fe7e:b5f6  prefixlen 64  scopeid 0x20<link>
        inet6 2601:408:c083:b6c0::d00d  prefixlen 128  scopeid 0x0<global>
        ether 3c:e4:b0:7e:b5:f6  txqueuelen 1000  (Ethernet)
        RX packets 3188898  bytes 678154090 (646.7 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1162074  bytes 293237366 (279.6 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wpan0: flags=195<UP,BROADCAST,RUNNING,NOARP>  mtu 123 ⑥
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 300  (UNSPEC)
        RX packets 108495  bytes 2539160 (2.4 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 2888  bytes 140523 (137.2 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

    ① You’ll want to see that the bcfserial driver has been loaded.

    ② There should be a lowpan0 interface.

    ③ There should be a link-local address for lowpan0.

    ④ There should be a global address for lowpan0.

    ⑤ Seeing some packets have been transmitted can give you some confidence.

    ⑥ The wpan0 interface should be there, but we have a 6LoWPAN adapter on top of it.

Note

You may find Linux-WPAN.org useful.

Setup Zephyr development on BeaglePlay#

  1. Download and setup Zephyr for BeaglePlay

    cd
sudo apt update
sudo apt install --no-install-recommends -y \
    gperf \
    ccache dfu-util \
    libsdl2-dev \
    libxml2-dev libxslt1-dev libssl-dev libjpeg62-turbo-dev libmagic1 \
    libtool-bin autoconf automake libusb-1.0-0-dev \
    python3-tk python3-virtualenv
wget https://github.com/zephyrproject-rtos/sdk-ng/releases/download/v0.15.1/zephyr-sdk-0.15.1_linux-aarch64_minimal.tar.gz
tar xf zephyr-sdk-0.15.1_linux-aarch64_minimal.tar.gz
rm zephyr-sdk-0.15.1_linux-aarch64_minimal.tar.gz
./zephyr-sdk-0.15.1/setup.sh -t arm-zephyr-eabi -c
west init -m https://git.beagleboard.org/beagleconnect/zephyr/zephyr --mr sdk zephyr-beagle-cc1352-sdk
cd $HOME/zephyr-beagle-cc1352-sdk
python3 -m virtualenv zephyr-beagle-cc1352-env
echo "export ZEPHYR_TOOLCHAIN_VARIANT=zephyr" >> $HOME/zephyr-beagle-cc1352-sdk/zephyr-beagle-cc1352-env/bin/activate
echo "export ZEPHYR_SDK_INSTALL_DIR=$HOME/zephyr-sdk-0.15.1" >> $HOME/zephyr-beagle-cc1352-sdk/zephyr-beagle-cc1352-env/bin/activate
echo "export ZEPHYR_BASE=$HOME/zephyr-beagle-cc1352-sdk/zephyr" >> $HOME/zephyr-beagle-cc1352-sdk/zephyr-beagle-cc1352-env/bin/activate
echo 'export PATH=$HOME/zephyr-beagle-cc1352-sdk/zephyr/scripts:$PATH' >> $HOME/zephyr-beagle-cc1352-sdk/zephyr-beagle-cc1352-env/bin/activate
echo "export BOARD=beagleplay" >> $HOME/zephyr-beagle-cc1352-sdk/zephyr-beagle-cc1352-env/bin/activate
source $HOME/zephyr-beagle-cc1352-sdk/zephyr-beagle-cc1352-env/bin/activate
west update
west zephyr-export
pip3 install -r zephyr/scripts/requirements-base.txt

  2. Activate the Zephyr build environment

    If you exit and come back, you’ll need to reactivate your Zephyr build environment.

    source $HOME/zephyr-beagle-cc1352-sdk/zephyr-beagle-cc1352-env/bin/activate

  3. Verify Zephyr setup for BeaglePlay

    (zephyr-beagle-cc1352-env) debian@BeaglePlay:~$ cmake --version
cmake version 3.22.1

CMake suite maintained and supported by Kitware (kitware.com/cmake).
(zephyr-beagle-cc1352-env) debian@BeaglePlay:~$ python3 --version
Python 3.9.2
(zephyr-beagle-cc1352-env) debian@BeaglePlay:~$ dtc --version
Version: DTC 1.6.0
(zephyr-beagle-cc1352-env) debian@BeaglePlay:~$ west --version
West version: v0.14.0
(zephyr-beagle-cc1352-env) debian@BeaglePlay:~$ ./zephyr-sdk-0.15.1/arm-zephyr-eabi/bin/arm-zephyr-eabi-gcc --version
arm-zephyr-eabi-gcc (Zephyr SDK 0.15.1) 12.1.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Build applications for BeaglePlay CC1352#

Now you can build various Zephyr applications

  1. Build and flash Blinky example

    cd $HOME/zephyr-beagle-cc1352-sdk/zephyr
west build -d build/play_blinky samples/basic/blinky
west flash -d build/play_blinky

  2. Try out Micropython

    cd
git clone -b beagleplay-cc1352 https://git.beagleboard.org/beagleplay/micropython
cd micropython
west build -d play ports/zephyr
west flash -d play
tio /dev/ttyS4

Build applications for BeagleConnect Freedom#

  1. Build and flash Blinky example

    cd $HOME/zephyr-beagle-cc1352-sdk/zephyr
west build -d build/freedom_blinky -b beagleconnect_freedom samples/basic/blinky
west flash -d build/freedom_blinky

  2. Try out Micropython

    cd
git clone -b beagleplay-cc1352 https://git.beagleboard.org/beagleplay/micropython
cd micropython
west build -d freedom -b beagleconnect_freedom ports/zephyr
west flash -d freedom
tio /dev/ttyACM0

Important

Nothing below here is tested

Flash applications to BeagleConnect Freedom#

And then you can flash the BeagleConnect Freedom boards over USB

  1. Make sure you are in Zephyr directory
    cd $HOME/bcf-zephyr
  2. Flash Blinky
    cc2538-bsl.py build/blinky

Debug applications over the serial terminal#

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