I've had a PCEngines APU2 gathering dust for a few years, and have recently decided to dust it off.
Since the last time the device has been powered on, there have been many great improvements to the firmware, and it was very-much due for an upgrade. The following steps outline how the firmware was upgraded on the APU from the already-installed operating system -- CentOS.
First, we will connect to the device over the serial port
screen /dev/tty.usbserial 115200
Then, we will install the flashrom utility that is needed to update the
firmware. Because it is not available in the default yum repositories, we
will enable the Extra Packages for Enterprise Linux (EPEL) repository before
installation.
sudo yum install epel-release
sudo yum install flashrom
Next, we will download the latest version of the firmware that is compatible with the APU2 device from the PC Engines release website: https://pcengines.github.io/.
curl -O https://3mdeb.com/open-source-firmware/pcengines/apu2/apu2_v4.11.0.1.rom
And finally, we will flash the firmware...
sudo flashrom -w apu2_v4.11.0.1.rom -p internal:boardmismatch=force
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