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<!doctype html><html lang=en-us><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta name=generator content="JBMAFP - github.com/mitjafelicijan/jbmafp"><link href="data:image/x-icon;base64,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" rel=icon type=image/x-icon><title>Simple world clock with eInk display and Raspberry Pi Zero</title><meta name=description content="Our team is spread across the world, from the USA all the way to Australia, sohaving some sort of world clock makes sense."><meta name=author content="Mitja Felicijan"><link rel=alternate type=application/rss+xml title="Mitja Felicijan's posts" href=https://mitjafelicijan.com/index.xml><link rel=alternate type=application/rss+xml title="Mitja Felicijan's notes" href=https://mitjafelicijan.com/notes.xml><style>:root{--border-color:gainsboro;--border-size:2px;--link-color:blue;--bg-color:#eee}*::selection{background:var(--link-color);color:#fff}*::-moz-selection{background:var(--link-color);color:#fff}*::-webkit-selection{background:var(--link-color);color:#fff}body{padding:2.5rem;max-width:1900px;background:#fff;font-family:sans-serif;line-height:1.35rem;font-size:16px}hr{border:0;border-bottom:var(--border-size)solid var(--border-color);margin-block-start:1.5rem}a{color:var(--link-color);text-decoration:none}h1,h2,h3{line-height:initial}h1{font-size:xx-large}footer{margin-block-start:2rem}cap{text-transform:capitalize}blockquote{font-style:italic}table{max-width:100%;border:var(--border-size)solid var(--border-color);border-collapse:separate;border-spacing:0}table thead tr th{border-bottom:var(--border-size)solid var(--border-color);text-align:left}table th,table td{padding:.5em .8em}ul.list li{padding:.2em 0}ul{line-height:1.35em}pre{text-wrap:nowrap;overflow-x:auto;padding:0 1em;border:var(--border-size)solid var(--border-color)}code{padding:0 3px;font-size:14px;border:0;background:var(--bg-color)}pre code{line-height:1.3em;background:#fff}pre,code,pre *,code *{font-family:monospace}figure{margin-inline-start:0;margin-inline-end:0}figcaption{width:800px;max-width:100%;text-align:center}figcaption p{margin:.3em 0 1.5em;font-style:italic}img,video,audio{width:800px;max-width:100%;border:var(--border-size)solid var(--border-color);padding:.5em}header nav{display:flex;gap:.9rem}article iframe{margin:0!important}audio::-webkit-media-controls-enclosure{border-radius:0}@media only screen and (max-width:600px){body{padding:.5em;word-wrap:break-word}header nav{gap:.7rem}header nav .hob{display:none}a{word-wrap:break-word}}</style><header><nav class=main itemscope itemtype=http://schema.org/SiteNavigationElement role=toolbar><a href=/>Home</a>
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<a href=/index.xml target=_blank class=hob>RSS</a></nav></header><main role=main><article itemtype=http://schema.org/Article><h1 itemtype=headline>Simple world clock with eInk display and Raspberry Pi Zero</h1><p><cap>post</cap>, Jun 26, 2021 on <a href=https://mitjafelicijan.com>Mitja Felicijan's blog</a><div><p>Our team is spread across the world, from the USA all the way to Australia, so
having some sort of world clock makes sense.<p>Currently, I am using an extension for Gnome called <a href=https://extensions.gnome.org/extension/2657/timezones-extension/>Timezone
extension</a>,
and it serves the purpose quite well.<p>But I also have a bunch of electronics that I bought through the time, and I am
not using any of them, and it's time to stop hording this stuff and use it in a
project.<p>A while ago I bought a small eInk display <a href="https://shop.pimoroni.com/products/inky-phat?variant=12549254217811">Inky
pHAT</a> and I
have a bunch of <a href=https://www.raspberrypi.org/products/raspberry-pi-zero/>Raspberry Pi's
Zero</a> lying around that
I really need to use.<figure><img loading="lazy" src=/posts/world-clock/hardware.jpg alt="Inky pHAT, Raspberry Pi Zero"></figure><p>Since the Inky <a href="https://shop.pimoroni.com/products/inky-phat?variant=12549254217811">Inky
pHAT</a> is
essentially a HAT, it can easily be added on top of the <a href=https://www.raspberrypi.org/products/raspberry-pi-zero/>Raspberry Pi
Zero</a>.<p>First, I installed the necessary software on Raspberry Pi with <code>pip3 install inky</code>.<p>And then I created a file <code>clock.py</code> in home directory <code>/home/pi</code>.<pre tabindex=0 style=background-color:#fff><code><span style=display:flex><span><span style=color:green>#!/usr/bin/env python</span>
</span></span><span style=display:flex><span><span style=color:green># -*- coding: utf-8 -*-</span>
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span><span style=color:#00f>import</span> sys
</span></span><span style=display:flex><span><span style=color:#00f>import</span> os
</span></span><span style=display:flex><span><span style=color:#00f>from</span> inky.auto <span style=color:#00f>import</span> auto
</span></span><span style=display:flex><span><span style=color:#00f>from</span> PIL <span style=color:#00f>import</span> Image, ImageFont, ImageDraw
</span></span><span style=display:flex><span><span style=color:#00f>from</span> font_fredoka_one <span style=color:#00f>import</span> FredokaOne
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span>clocks = [
</span></span><span style=display:flex><span> <span style=color:#a31515>'America/New_York'</span>,
</span></span><span style=display:flex><span> <span style=color:#a31515>'Europe/Ljubljana'</span>,
</span></span><span style=display:flex><span> <span style=color:#a31515>'Australia/Brisbane'</span>,
</span></span><span style=display:flex><span>]
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span>board = auto()
</span></span><span style=display:flex><span>board.set_border(board.WHITE)
</span></span><span style=display:flex><span>board.rotation = 90
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span>img = Image.new(<span style=color:#a31515>'P'</span>, (board.WIDTH, board.HEIGHT))
</span></span><span style=display:flex><span>draw = ImageDraw.Draw(img)
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span>big_font = ImageFont.truetype(FredokaOne, 18)
</span></span><span style=display:flex><span>small_font = ImageFont.truetype(FredokaOne, 13)
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span>x = board.WIDTH / 3
</span></span><span style=display:flex><span>y = board.HEIGHT / 3
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span>idx = 1
</span></span><span style=display:flex><span><span style=color:#00f>for</span> clock <span style=color:#00f>in</span> clocks:
</span></span><span style=display:flex><span> ctime = os.popen(<span style=color:#a31515>'TZ="</span><span style=color:#a31515>{}</span><span style=color:#a31515>" date +"</span><span style=color:#a31515>%a</span><span style=color:#a31515>,%H:%M"'</span>.format(clock))
</span></span><span style=display:flex><span> ctime = ctime.read().strip().split(<span style=color:#a31515>','</span>)
</span></span><span style=display:flex><span> city = clock.split(<span style=color:#a31515>'/'</span>)[1].replace(<span style=color:#a31515>'_'</span>, <span style=color:#a31515>' '</span>)
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span> draw.text((15, (idx*y)-y+10), city, fill=board.BLACK, font=small_font)
</span></span><span style=display:flex><span> draw.text((110, (idx*y)-y+7), str(ctime[0]), fill=board.BLACK, font=big_font)
</span></span><span style=display:flex><span> draw.text((155, (idx*y)-y+7), str(ctime[1]), fill=board.BLACK, font=big_font)
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span> idx += 1
</span></span><span style=display:flex><span>
</span></span><span style=display:flex><span>board.set_image(img)
</span></span><span style=display:flex><span>board.show()
</span></span></code></pre><p>And because eInk displays are rather slow to refresh and the clock requires
refreshing only once a minute, this can be done through cronjob.<p>Before we add this job to cron we need to make <code>clock.py</code> executable with <code>chmod +x clock.py</code>.<p>Then we add a cronjob with <code>crontab -e</code>.<pre tabindex=0 style=background-color:#fff><code><span style=display:flex><span>* * * * * /home/pi/clock.py
</span></span></code></pre><p>So, we end up with a result like this.<figure><img loading="lazy" src=/posts/world-clock/world-clock.jpg alt="World Clock"></figure><p>And for the enclosure that can be 3D printed, but I haven't yet something like
this can be used.</p><iframe id=vs_iframe src="https://www.viewstl.com/?embedded&url=https%3A%2F%2Fmitjafelicijan.com%2Fposts%2Fworld-clock%2Fenclosure.stl&color=gray&bgcolor=white&edges=no&orientation=front&noborder=no" style=border:0;margin:0;width:100%;height:400px></iframe><p>You can download my <a href=/posts/world-clock/enclosure.stl>STL file for the enclosure
here</a>, but make sure that dimensions make
sense and also opening for USB port should be added or just use a drill and some
hot glue to make it stick in the enclosure.</div></article></main><section><hr><h2>Posts from blogs I follow around the net</h2><ul><li><a href=https://utcc.utoronto.ca/~cks/space/blog/linux/NFSv4ServerLockClients target=_blank rel=noopener>Finding which NFSv4 client owns a lock on a Linux NFS(v4) server</a> — <a href=https://utcc.utoronto.ca/~cks/space/blog/>Chris's Wiki :: blog</a><div>A while back I wrote an entry about finding which NFS client owns
a lock on a Linux NFS server, which turned
out to be specific to NFS v3 (which I really should have seen coming,
since it involved NLM and lockd). Finding the NFS v4 client that
owns a lock is, depending on your perspective, either simpl…<li><a href=http://www.landley.net/notes-2023.html#28-10-2023 target=_blank rel=noopener>October 28, 2023</a> — <a href=http://www.landley.net/notes-2023.html>Rob Landley's Blog Thing for 2023</a><div>Oh good grief, two of my least favorite licensing people, Larry Rosen
and Bradley Kuhn, are interacting on the OSI's license-discuss
list where the're doing
bad computer history and insisting that a guy Larry Rosen
coincidentally interviewed for a book years ago is clearly the origin of
somethin…<li><a href="http://offbeatpursuit.com:80/blog/?id=25" target=_blank rel=noopener>A fix by any other name</a> — <a href=http://offbeatpursuit.com:80/blog/>WLOG - blog</a><div>tags:
i2c, plan9
Another month, another file system.
Well, if you can’t fix it in software, fix it in hardware (looking at
you, bme680, we’re not
done yet). The show must go on, as they say, and I would like my
experiments to go on.
So a “new” addition to the environmental sensor family connected to
the h…<li><a href=https://mirzapandzo.com/next-image-url-parameter-is-valid-but-upstream-response-is-invalid target=_blank rel=noopener>Next/Image "url" parameter is valid but upstream response is invalid</a> — <a href=https://mirzapandzo.com/>Mirza Pandzo's Blog</a><div>Getting "url" parameter is valid but upstream response is invalid error with Next/Image on WSL2<li><a href=https://drewdevault.com/2023/10/13/Going-off-script.html target=_blank rel=noopener>Going off-script</a> — <a href=https://drewdevault.com>Drew DeVault's blog</a><div>There is a phenomenon in society which I find quite bizarre. Upon our entry to
this mortal coil, we are endowed with self-awareness, agency, and free will.
Each of the 8 billion members of this human race represents a unique person, a
unique worldview, and a unique agency. Yet, many of us have the sam…<li><a href=https://szymonkaliski.com/writing/2023-10-02-building-a-diy-pen-plotter/ target=_blank rel=noopener>Building a DIY Pen Plotter</a> — <a href=http://github.com/dylang/node-rss>Szymon Kaliski</a><div>This article documents my learnings from designing and building a DIY Pen Plotter during the summer of 2023.
My ultimate goal is to build my…<li><a href=https://neil.computer/notes/chart-of-accounts-for-startups-and-saas-companies/ target=_blank rel=noopener>Chart of Accounts for Startups and SaaS Companies</a> — <a href=https://neil.computer/>Neil Panchal</a><div>Accounting is fundamental to starting a business. You need to have a basic understanding of accounting principles and essential bookkeeping. I had to learn it. There was no choice. For filing taxes, your CPA is going to ask you for an Income Statement (also known as P/L statement). If<li><a href=https://journal.valeriansaliou.name/deploy-a-nomad-cluster-on-alpine-linux-with-vultr/ target=_blank rel=noopener>Deploy a Nomad Cluster on Alpine Linux with Vultr</a> — <a href=https://journal.valeriansaliou.name/>Valerian Saliou</a><div>After spending countless hours trying to understand how to deploy my apps on Kubernetes for the first time to host Mirage, an AI API service that I run, I ended up making myself a promise that the next app I work on would be using a more productive & simpler<li><a href=https://jcs.org/2023/10/25/wifi_da target=_blank rel=noopener>BlueSCSI Wi-Fi Desk Accessory 1.0 Released</a> — <a href=https://jcs.org/>joshua stein</a><div>BlueSCSI Wi-Fi Desk Accessory
1.0 has been released:
wifi_da-1.0.sit
(StuffIt 3 archive)
SHA256: ccfc9d27dd5da7412d10cef73b81119a1fec3848e4d1d88ff652a07ffdc6a69aSHA1: ff124972f202ceda6d7fa4788110a67ccda6a13a
This is the initial public release of my BlueSCSI Wi-Fi Desk Accessory for
classic MacOS.<li><a href=https://michael.stapelberg.ch/posts/2023-10-25-my-all-flash-zfs-network-storage-build/ target=_blank rel=noopener>My 2023 all-flash ZFS NAS (Network Storage) build</a> — <a href=https://michael.stapelberg.ch/>Michael Stapelbergs Website</a><div>For over 10 years now, I run two self-built NAS (Network Storage) devices which serve media (currently via Jellyfin) and run daily backups of all my PCs and servers.
In this article, I describe my goals, which hardware I picked for my new build (and why) and how I set it up.
Design Goals
I use my netw…</ul><p>Generated with <a href=https://git.sr.ht/~sircmpwn/openring target=_blank rel=noopener>openring</a>.</section><footer><hr><p><big><strong>Want to comment or have something to add?</strong></big><p>You can write me an email
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