I got my first Raspberry Compute Module 4 and installed it in a Geekpi CM4 Router Board.  And then cue the fun.  It is cool but it isn’t quite ready for plug and play prime time.   It was quite a challenge to get everything running.

First of all there are several images to download on the GitHub page and I just wasn’t sure which one to use.   The image that supposedly allowed the OLED display to work somehow or another didn’t have a working ETH1 wan port after installation.  A router without a wan port isn’t worth a shit and it sure isn’t a router.  Pardon my French.

So then the image with the ETH1 wan port working didn’t have a working OLED display.  FML.   In the great scheme of things the OLED being functional isn’t that important and that’s the direction I decided to go.  Then I figured out how to get the OLED on which is a hack.

Here’s how it happened:

First install OpenWRT on your Compute Module by using this file from the Github link above.

openwrt-bcm2711-rpi-4-ext4-rtl8168-factory.img

This one has the functional wan port. But you have to add it manually (ETH1 = WAN)

WAN port depicted (click pic to enlarge)

And almost everything you need to get the OLED going is here.

If you go Services > OLED you’ll find that page is non functional.  ssh into your Openwrt and issue these three commands.

opkg update
opkg install luci-compat
opkg install nano

The nano one isn’t totally necessary if you know how to use vi.  I hate vi.

Once luci-compat is installed the page will work but you’ll get a message that says “OLED Not Running”. Crap.

So now you need to take nano and add a line of code.

nano /etc/init.d/oled

Add this line to the start() area:

ln -s /dev/i2c-1 /dev/i2c-0

It will look like this:

start() {
        ln -s /dev/i2c-1 /dev/i2c-0
        enabled=$(uci get oled.@oled[0].enable)
        if [ $enabled -eq 0 ]; then
                exit 0
        fi

Hit Ctl + X and then Y to save.  Now reboot.  Navigate to the Services > OLED page and voila’. In Green it states “OLED Running”

OLED Running (click pic to enlarge)

Now everything works.  Next up will be to add a hotspot so this device can be a travel router.  Then maybe configure OpenVPN for security.

Guys like me like to fumble around with stuff and make it work but it seems like they could have a working OpenWRT image ready to roll.  Just my opinion.  You have to mess with it to make it work.