Move back to JBMAFP

1 files changed, 107 insertions, 0 deletions

diff --git a/content/posts/2021-06-26-simple-world-clock.md b/content/posts/2021-06-26-simple-world-clock.md
new file mode 100644
index 0000000..e72744c
--- /dev/null
+++ b/content/posts/2021-06-26-simple-world-clock.md
@@ -0,0 +1,107 @@
+---
+title: Simple world clock with eInk display and Raspberry Pi Zero
+url: /simple-world-clock-with-eiink-display-and-raspberry-pi-zero.html
+date: 2021-06-26T12:00:00+02:00
+type: post
+draft: false
+---
+
+Our team is spread across the world, from the USA all the way to Australia, so
+having some sort of world clock makes sense.
+
+Currently, I am using an extension for Gnome called [Timezone
+extension](https://extensions.gnome.org/extension/2657/timezones-extension/),
+and it serves the purpose quite well.
+
+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.
+
+A while ago I bought a small eInk display [Inky
+pHAT](https://shop.pimoroni.com/products/inky-phat?variant=12549254217811) and I
+have a bunch of [Raspberry Pi's
+Zero](https://www.raspberrypi.org/products/raspberry-pi-zero/) lying around that
+I really need to use.
+
+![Inky pHAT, Raspberry Pi Zero](/assets/posts/world-clock/hardware.jpg)
+
+Since the Inky [Inky
+pHAT](https://shop.pimoroni.com/products/inky-phat?variant=12549254217811) is
+essentially a HAT, it can easily be added on top of the [Raspberry Pi
+Zero](https://www.raspberrypi.org/products/raspberry-pi-zero/).
+
+First, I installed the necessary software on Raspberry Pi with `pip3 install
+inky`.
+
+And then I created a file `clock.py` in home directory `/home/pi`.
+
+```python
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+import sys
+import os
+from inky.auto import auto
+from PIL import Image, ImageFont, ImageDraw
+from font_fredoka_one import FredokaOne
+
+clocks = [
+  'America/New_York',
+  'Europe/Ljubljana',
+  'Australia/Brisbane',
+]
+
+board = auto()
+board.set_border(board.WHITE)
+board.rotation = 90
+
+img = Image.new('P', (board.WIDTH, board.HEIGHT))
+draw = ImageDraw.Draw(img)
+
+big_font = ImageFont.truetype(FredokaOne, 18)
+small_font = ImageFont.truetype(FredokaOne, 13)
+
+x = board.WIDTH / 3
+y = board.HEIGHT / 3
+
+idx = 1
+for clock in clocks:
+  ctime = os.popen('TZ="{}" date +"%a,%H:%M"'.format(clock))
+  ctime = ctime.read().strip().split(',')
+  city = clock.split('/')[1].replace('_', ' ')
+
+  draw.text((15, (idx*y)-y+10), city, fill=board.BLACK, font=small_font)
+  draw.text((110, (idx*y)-y+7), str(ctime[0]), fill=board.BLACK, font=big_font)
+  draw.text((155, (idx*y)-y+7), str(ctime[1]), fill=board.BLACK, font=big_font)
+
+  idx += 1
+
+board.set_image(img)
+board.show()
+```
+
+And because eInk displays are rather slow to refresh and the clock requires
+refreshing only once a minute, this can be done through cronjob.
+
+Before we add this job to cron we need to make `clock.py` executable with `chmod
++x clock.py`.
+
+Then we add a cronjob with `crontab -e`.
+
+```txt
+* * * * * /home/pi/clock.py
+```
+
+So, we end up with a result like this.
+
+![World Clock](/assets/posts/world-clock/world-clock.jpg)
+
+And for the enclosure that can be 3D printed, but I haven't yet something like
+this can be used.
+
+<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>
+
+You can download my [STL file for the enclosure
+here](/assets/posts/world-clock/enclosure.stl), 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.