Raspberry Pi Zero W and Funtoo

After finding the PaPiRus ePaper panel, I picked up a Raspberry Pi Zero W to drive it. To be perfectly honest, the early Raspberry Pis never really excited me. However, the Raspberry Pi Zero’s small footprint caught my attention. Add in WiFi and Bluetooth, as found on the Zero W, and you have a solid IoT starter board.

Thanks to the popularity of the Raspberry Pi, both Funtoo and Gentoo have guides on setting up Funtoo/Gentoo on a Raspberry Pi. Getting a base system up and running is straightforward. Though, if you have to compile anything it will take a while.

WiFi

Getting WiFi to work requires some compiling. Funtoo’s guide for setting up WiFi on the Raspberry Pi 3 works for the Zero W for the driver side. On the userland side, you will probably want something like NetworkManager and wpa_supplicant. Unfortunately, neither package come installed in the base install for Funtoo/Gentoo.

Normally, chrooting in from a liveCD with working networking, installing the requisite package, and rebooting is sufficient. However, in this case, you’ll need to setup Qemu on your workstation and then use it to chroot into the ARM environment to compile and install NetworkManager. This will take quite some time.

Playing with PaPiRus

PaPiRus is a ePaper pHAT for the Raspberry Pi Zero. It contains an I2C LM75 temperature sensor, a few push button switches, a SPI NOR flash, and a ePaper panel. Unfortunately, it does not have an I2C memory device to store the device tree overlay information needed for auto-configuration of the SoC.

Since the installer for PaPiRus’ driver, and the manual instructions for that matter, assume a Debian based system, they do not work with Funtoo. Instead, follow the “Install Driver – Option 2” instructions, and rather than apt-get, use the following:

emerge -av sys-fs/fuse dev-python/pillow media-fonts/freefonts

After running make rpi-install the last few steps diverge from the “Install Driver – Option 2” instructions. Since Funtoo by default uses OpenRC rather than Systemd, the epd-fuse.service isn’t going to work. Instead, the OpenRC script below can be used (save as /etc/init.d/epd-fuse).

#!/sbin/openrc-run
# Copyright 1999-2007 Gentoo Foundation
# Distributed under the terms of the GNU General Public License v2

EPD_MOUNTPOINT=/dev/epd

depend() {
        need localmount
}

start() {
        EPD_SIZE=2.0
        EPD_OPTS="-o allow_other -o default_permissions"
        ebegin "Starting epd-fuse"
        mkdir -p $EPD_MOUNTPOINT
        if ! grep -qw fuse /proc/filesystems; then
                modprobe fuse >/dev/null 2>&1 || eerror $? "Error loading fuse module"
        fi
        if ! grep -qw $EPD_MOUNTPOINT /proc/mounts; then
                /usr/sbin/epd_fuse --panel=$EPD_SIZE $EPD_OPTS $EPD_MOUNTPOINT >/dev/null 2>&1 || \
                        eerror $? "Error mounting control filesystem"
        fi
        eend ${?}
}

stop() {

        ebegin "Stopping epd-fuse"
        if grep -qw $EPD_MOUNTPOINT /proc/mounts; then
                umount $EPD_MOUNTPOINT >/dev/null 2>&1 || \
                        eerror $? "Error unmounting control filesystem"
        fi
        eend ${?}
}

After saving the epd-fuse script, rc-service epd-fuse start can be used to start the driver. Of course, installing Systemd and uninstalling OpenRC is an option. However, that is quite a bit of effort for something that is overkill for a Raspberry Pi.

Other things to consider, while Funtoo places fonts under /usr/share/fonts, the font packages and directory structure of /usr/share/fonts differs from what PaPiRus expects. The easy way to resolve this is to modify the examples with the correct font location.

Pitfalls

Rather than the older module blacklist/modprobe method for enabling various SOC features, the Raspberry Pi kernel has moved to Device Tree Blobs. Which is not entirely bad. However, they can be difficult to get working.

For short-term testing, to get the PaPiRus to work, I ended up using dtoverlay to enable the SPI and I2C buses, and then had to use modprobe to remove the LM75 driver so that the I2C bus was available to the epd-fuse driver.

-John Havlik

[end of transmission, stay tuned]

Making Sense of the *title Breadcrumb Template Tags

Currently, there are several, closely related template tags that each exhibit slightly different behaviors. These are: %title%, %htitle%, %ftitle%, and %fhtitle%. As their names suggest, they will be replaced with the resource’s title. However, how this title is processed differs between the tags.

Note that the “Max Title Length” setting is deprecated. Hence, both %ftitle% and %fhtitle% are deprecated and not recommended for use. They are included in this discussion for the sake of completeness.

Below is a table outlining the behavior of these tags for the same title with the max length set to ~10 characters and with the max length setting disabled.

Template Tag Max Title Length1 Title Result
%title% 10 Hello <em>World</em> Leaders Hello <em…
%htitle% 10 Hello <em>World</em> Leaders Hello <em…
%ftitle% 10 Hello <em>World</em> Leaders Hello World Leaders
%fhtitle% 10 Hello <em>World</em> Leaders Hello <em>World</em> Leaders
%title% Disabled Hello <em>World</em> Leaders Hello World Leaders
%htitle% Disabled Hello <em>World</em> Leaders Hello <em>World</em> Leaders

%title% and %htitle%

Notice that the resulting strings for the standard %title% tag and the %ftitle% tag do not contain HTML tags. Thus, they are safe for use within HTML tag attributes (e.g. the title attribute). To maintain HTML tags present in the resource’s title, use the %htitle% tag.

%ftitle% and %fhtitle%

Note that the Max Title Length setting does not affect the resulting string for the %ftitle% and %fhtitle% template tags. In fact, by design, they are the same as %title% and %htitle% when “Max Title Length” is disabled. However, note that since the Max Title Length setting is deprecated, these template tags are as well.

Lastly, note that when using the Max Title Length setting, HTML tags may be left open or even incomplete. Therefore, it is strongly recommended that CSS is used to trim the breadcrumb title length rather than the deprecated Max Title Length setting. An additional benefit to using CSS is it does not mess with the actual content of the breadcrumb trail, allowing search engines to pick up on the full titles rather than the trimmed ones.

-John Havlik

[end of transmission, stay tuned]

Notes:

  1. Note that use of the Max title Length setting has been deprecated in favor of using CSS to trim Breadcrumb titles lengths.

Supermicro X10SDV-7TP4F Heatsink Swap

After assembling my new home server, I ran into a bit of a heat issue. The Xeon-D SOC would get quite hot under load (80C), and was a little warmer than desired while idling (40C). Attempting to cool itself off, the motherboard kept the chassis fans spinning fast enough to be annoyingly loud. Since the heatsink installed on the motherboard was designed for 1U compatibility, and the case I’m using is 2U tall, it was not getting the airflow it was designed for.

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Repairing the 24 Pin ATX Power Connector

As part of my new home server build, I picked up a used Super Micro SC216 chassis. This chassis has 24x 2.5″ drive bays in the front, 3x 80mm fans in the mid-plane, 7 half-height expansion slots in the rear, and dual PSUs. While dual PSUs are overkill, the rest of the features should make for a nice Xeon D based storage chassis.

Once the chassis arrived, I noticed that the previous owner had mutilated the 24 pin ATX power cable. The PS-ON, and the GND pin next to it, had been clipped at the connector and spliced together with a crimped pigtail splice. Typically, this is done so that the PSUs are always on when using the chassis as an external JBOD box. Since I would like the soft power button to function properly on the case, this needed to be fixed.

Luckily, I had an 24 pin ATX power cable from a dead PSU. Using that cable as a donor, I replaced the PS-ON and GND pins in the power connector. Then, I made a solder splice between the PS-ON (and GND) in the power distributor and the corresponding replacement in the connector. With the lines reconnected, I was able to power up my test board (an old core 2 duo board). Now the chassis is ready for a Xeon D motherboard.

-John Havlik

[end of transmission, stay tuned]