A Raspberry Pi router build for the Waveshare CM4-DUAL-ETH-4G/5G-BOX, using the Sierra Wireless EM7565 4G LTE modem.
After borrowing my Dad's Cradlepoint IBR900, I decided I wanted to build a similar style portable 4G access point/router/firewall.
I bought a SixFab SIM and built a fast 4G router using Waveshare's dual Ethernet 4G/5G kit along with a Raspberry Pi Compute Module 4.
The build runs OpenWRT, but since it is a custom configuration, you have to manually compile an OpenWRT image to flash to the Pi's microSD card or eMMC storage.
Install Docker (and Docker Compose if not using Docker Desktop).
Bring up the cross-compile environment:
docker-compose up -d
Log into the running container:
docker attach openwrt-build
You will be dropped into a shell inside the container's /build/openwrt
directory. From here you can work on compiling OpenWRT.
After you
exit
out of that shell, the Docker container will stop, but will not be removed. If you want to jump back into it, you can rundocker start openwrt-build
anddocker attach openwrt-build
.
The container should have OpenWRT's source code checked out inside he /build/openwrt
directory. If you would like, run git pull
inside the directory to make sure the latest OpenWRT changes are present.
First, run the following command to open menuconfig
and select options:
make menuconfig
Choose the Raspberry Pi BCM 2711 for the CM4 as the target platform:
Broadcom BCM27xx
BCM 2711 Boards (64 bit)
Then select additional packages and configuration. for the Waveshare board, I added the following options:
TODO: This section currently installs practically all the different potential points of entry for QMI, MBIM, etc. modes. For final production use, I probably only need to install a small subset of the packages for the wireless 4G modem, depending on how I want to use it.
kmod-usb-net-rtl8152
kmod-usb2
(and kmod-usb3
)luci-ssl
kmod-usb-net-sierrawireless
usb-modeswitch
minicom
uqmi
kmod-usb-net-cdc-mbim
kmod-usb-net-qmi-wwan
kmod-usb-serial-option
(optional - for AT commands)kmod-usb-serial-qualcomm
kmod-usb-serial-sierrawireless
kmod-usb-wdm
modemmanager
luci-proto-modemmanager
(Make sure to choose the [*] built-in
option, not [M] module
option for each of the above selections.)
TODO: I currently don't have all the /etc/config/network, /etc/config/dhcp, and /etc/config/wireless files set up in this repo—I should do that so I don't have to sit there configuring the router on first boot.
Then, if you would like to customize Linux kernel options, run the following command (this is often not necessary):
make -j $(nproc) kernel_menuconfig
TODO: See Get onboard Raspberry Pi CM4 WiFi module working. Some alpha CM4 modules have a different wireless chipset that requires copying three firmware files over from Raspberry Pi OS to the custom buildroot files directory.
TODO: Also need to make sure the config.txt change is made to use the external antenna (otherwise internal antenna gets zero signal).
And finally, compile OpenWRT and build the image:
make -j $(nproc)
After make
is finished, you should have a file named openwrt-bcm27xx-bcm2711-rpi-4-ext4-factory.img.gz
inside /build/openwrt/bin
.
You will need to flash that image file to the Raspberry Pi to boot OpenWRT.
There is also a
ext4-sysupgrade
image file; this file can be used to upgrade an already-built OpenWRT system.
First, inside the Docker container, copy the build files out to the shared images
folder:
cp /build/openwrt/bin/targets/bcm27xx/bcm2711/*.img.gz /images
Then, use Raspberry Pi Imager, Etcher, or some other image-writing tool to write the uncompressed .img
file to a microSD card or the Pi's eMMC directly.
Plug in a USB-C power supply, and plug the ETH0 port into your computer (preferred) or network (this can cause issues). The default OpenWRT configuration sets up the router at 192.168.1.1, so visit that URL in the browser: https://192.168.1.1
On the first visit, you'll get an HTTPS certificate warning, which you can ignore. On the login page, use root
for the username and leave the password field blank.
You should set a strong password for the root account immediately, to keep your router secure!
TODO.
Jeff Geerling