Stephen Royle

As a project idea for a young engineer we wanted to build a **Raspberry
Pi-based Weather Station**. Our last attempt at building something -- a
sound-responsive LED display -- was a failure. So it was important to
build something **really easy** to help us get back on track. Here are
some notes.

We essentially followed [this
guide](https://learn.adafruit.com/raspberry-pi-e-ink-weather-station-using-python/overview)
from Adafruit which links out to [this
guide](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux/circuitpython-raspi)
for the CircuitPython part. Both were easy enough to understand although
there are a few choices to make, so I thought this short post would be
worth it to show how we got this project working.

## Hardware {#hardware .wp-block-heading}

First choice was hardware. There's a chip shortage at the moment and
although I wanted to build this on a Pi ZeroW, I couldn't source one. I
happened to have a Raspberry Pi 3A which was unused. This model is wi-fi
enabled, so I went ahead with it. For the screen, I bought an Adafruit
2.13″ Monochrome E-Ink Bonnet for Raspberry Pi (Think Ink) from the Pi
Hut. This is as simple as it gets because the bonnet just sits on the
GPIO pins on the Pi and no further fuss is needed. You can do this build
using other, simpler boards and use a display that requires wiring in,
but I knew my young companion would not have the patience for that. Our
Pi 3A was already in a Pimironi rainbow case. It turned out that the
bonnet could sit on the pins and be clear of the case, so that all
worked out.

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<img
src="https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5555.jpeg?resize=640%2C480&amp;ssl=1"
class="wp-image-2742" loading="lazy" decoding="async"
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data-attachment-id="2743"
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data-orig-file="https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5556-scaled.jpeg?fit=2560%2C1920&amp;ssl=1"
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sizes="(max-width: 640px) 100vw, 640px" data-recalc-dims="1" width="640"
height="480" />
</figure>
<figcaption>The weather station in action</figcaption>
</figure>

## On to the setup {#on-to-the-setup .wp-block-heading}

Setting up a Raspberry Pi is straightforward. Just use the imager to
write the OS to the SD card. Configure and enable SSH, and away you go.
First step is to enable the e-Ink display with CircuitPython and then
install the weather station code.

### CircuitPython setup {#circuitpython-setup .wp-block-heading}

The instructions for this are straightforward but they start on the
third page of [this
guide](https://learn.adafruit.com/circuitpython-on-raspberrypi-linux/overview).
So, in brief over ssh or on the Pi itself if you have attached a
monitor:

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install python3-pip
sudo pip3 install --upgrade setuptools
cd ~
sudo pip3 install --upgrade adafruit-python-shell
wget https://raw.githubusercontent.com/adafruit/Raspberry-Pi-Installer-Scripts/master/raspi-blinka.py
sudo python3 raspi-blinka.py
```
:::

Next you need to verify that I2C and SPI are enabled.

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
ls /dev/i2c* /dev/spi*
```
:::

Should give

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .plain; .gutter: .false; .title: .; .notranslate title=""}
/dev/i2c-1 /dev/spidev0.0 /dev/spidev0.1
```
:::

We ran the suggested test file `blinkatest.py` which is described on the
page, but you could skip if you want.

Next there are just a couple of steps required on the Pi before you can
install the Weather Station code.

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
sudo pip3 install adafruit-circuitpython-epd
sudo apt-get install fonts-dejavu
sudo apt-get install python3-pil
```
:::

That's it for CircuitPython setup.

### Weather station setup {#weather-station-setup .wp-block-heading}

To make requests we need an API key for OpenWeatherMap.org -- it's free
and sign-up is [here](https://home.openweathermap.org/users/sign_up).
You should get an email with your 33 character API key. Next, we need
the code to run the weather station.

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
wget -O EInk_Bonnet_Weather_Station.zip https://learn.adafruit.com/pages/19816/elements/3075247/download?type=zip
```
:::

Here, I am using the code from the guide. There is a [GitHub
repo](https://github.com/adafruit/Adafruit_Learning_System_Guides/tree/main/EInk_Bonnet_Weather_Station)
which may be more up-to-date.

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
unzip EInk_Bonnet_Weather_Station.zip
cd EInk_Bonnet_Weather_Station/
sudo nano code.py
```
:::

The code you downloaded needs to be edited to add your API key and your
location. Place these between quotes after the variables
`OPEN_WEATHER_TOKEN` and `LOCATION`

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .plain; .gutter: .false; .title: .; .notranslate title=""}
# You'll need to get a token from openweathermap.org, looks like:
# 'b6907d289e10d714a6e88b30761fae22'
OPEN_WEATHER_TOKEN = ""
```
:::

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .plain; .gutter: .false; .title: .; .notranslate title=""}
# Use cityname, country code where countrycode is ISO3166 format.
# E.g. "New York, US" or "London, GB"
LOCATION = "Manhattan, US"
```
:::

The most challenging part of this project was getting my young companion
to rekey the 33 character API code in `nano` ! Exit nano by ctrl + x and
confirm the save with y.

Now, if you run it, it should work.

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
python3 weather.py
```
:::

And sure enough:

<figure class="wp-block-image size-large">
<img
src="https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551.jpeg?resize=640%2C853&amp;ssl=1"
class="wp-image-2747" loading="lazy" decoding="async"
data-attachment-id="2747"
data-permalink="https://quantixed.org/2022/06/07/weather-report-building-a-weather-station/img_5551/"
data-orig-file="https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?fit=1920%2C2560&amp;ssl=1"
data-orig-size="1920,2560" data-comments-opened="1"
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data-image-title="IMG_5551" data-image-description=""
data-image-caption=""
data-medium-file="https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?fit=225%2C300&amp;ssl=1"
data-large-file="https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?fit=640%2C853&amp;ssl=1"
srcset="https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?resize=768%2C1024&amp;ssl=1 768w, https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?resize=225%2C300&amp;ssl=1 225w, https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?resize=1152%2C1536&amp;ssl=1 1152w, https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?resize=1536%2C2048&amp;ssl=1 1536w, https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?w=1920&amp;ssl=1 1920w, https://i0.wp.com/quantixed.org/wp-content/uploads/2022/06/IMG_5551-scaled.jpeg?w=1280&amp;ssl=1 1280w"
sizes="(max-width: 640px) 100vw, 640px" data-recalc-dims="1" width="640"
height="853" />
<figcaption>Success!</figcaption>
</figure>

Note that if python3 is the default on your system (it should be) you
can just use `python` rather than `python3`

The code is set to refresh the display and update the weather every five
minutes.

There is some more detail on the guide about how to get things working
more smoothly. Here is a quick summary of what we did.

### Final touches {#final-touches .wp-block-heading}

It's recommended to move the font into the system fonts. From home:

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
sudo mkdir /usr/share/fonts/truetype/meteocons
sudo cp EInk_Bonnet_Weather_Station/meteocons.ttf /usr/share/fonts/truetype/meteocons/meteocons.ttf
```
:::

Then edit the file `weather_graphics.py`

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
cd EInk_Bonnet_Weather_Station/
sudo nano weather_graphics.py
```
:::

so that the location of the font is correct, i.e. edit this line to
read:

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .plain; .gutter: .false; .title: .; .notranslate title=""}
icon_font = ImageFont.truetype("/usr/share/fonts/truetype/meteocons/meteocons.ttf", 48)
```
:::

Then edit `code.py` so that a) it shows the temperature in celsius and
b) runs correctly on boot:

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .plain; .gutter: .false; .title: .; .notranslate title=""}
display.rotation = 1

gfx = Weather_Graphics(display, am_pm=False, celsius=True)
weather_refresh = None

# when running on boot using rc.local we need a delay to allow network setup
time.sleep(20)

while True:
```
:::

Now, b above is a hack to get around a problem that took a while to
resolve. We wanted the weather station to just work on booting up with
no further maintenance required.

I moved `code.py` and `weather_graphics.py` out of their directory and
into home to make things simpler. Now to run on boot we can add this
line to `rc.local` just run

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .bash; .title: .; .notranslate title=""}
sudo nano /etc/rc.local
```
:::

and then add

::: {.wp-block-syntaxhighlighter-code}
``` {.brush: .plain; .gutter: .false; .title: .; .notranslate title=""}
python /home/username/code.py &
```
:::

before the line `exit 0`

What this does is runs this line at the end of the boot sequence. The
ampersand `&` at the end of the line is very important as it means that
the Pi is free to do other things without waiting for `code.py` to
finish (which it doesn't, it just continually refreshes).

While this worked, it gave an error because the boot sequence completed,
and the code ran for the first iteration before a network connection was
established. The result was that the script crashed. Rather than do
anything more complicated on the system side, I introduced a short delay
until the first request to OpenWeather is made (this is the hack "b"
above).

Result: the Weather Station runs nicely and will just start working when
plugged in at a new location.

## Conclusion {#conclusion .wp-block-heading}

After a previous build that became very complicated, it was important to
build something simple that "just worked". My young companion was very
pleased that she managed to make the weather station and that it
accurately reports the weather.

---

The post title comes from a band this time. How could it not be "Weather
Report"?


As a project idea for a young engineer we wanted to build a
<strong>
 Raspberry Pi-based Weather Station
</strong>
. Our last attempt at building something – a sound-responsive LED display – was a failure. So it was important to build something
<strong>
 really easy
</strong>
to help us get back on track. Here are some notes. We essentially followed this guide from Adafruit which links out to this guide for the CircuitPython part.

Rogue Scholar Beiträge

Weather Report: building a weather station