Add old draft post and new raw HTML shortcode.

content/posts/2020-05-15-gpio-webhook/index.md

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+---
+title: Remotely controlled blinkenlights with arduino
+date: 2020-05-15
+thumbnail: /thumbnails/blinkenlights.jpg
+tags:
+  - arduino
+  - electronics
+  - esp8266
+  - golang
+  - programming
+  - technology
+---
+
+{{< raw >}}
+<p class="l-deprecation_warning">
+This post sat in drafts for years, and is being published as-is. I might update it at some point, but probably not. Sorry!
+</p>
+{{< /raw >}}
+
+There are a lot of reasons I might not want someone to knock on or open my office door.
+I work from home, which means meetings get interrupted. I have sensory processing issues,
+which means sometimes I can barely deal with human voices. I have an anxiety disorder,
+which means other times I can't deal with, well, human interaction.
+
+Maybe it's stir-craziness during quarantine, or maybe this is just who I am, but I decided
+to solve this problem in the most convoluted way I could think of. So I wrote a server and
+arduino client for controlling gpio pins over wifi, and built myself a status indicator light.
+
+## The build
+
+Here is the initial prototype:
+
+{{< imgproc "breadboard.jpg" >}}
+  Breadboard with wires, LEDs, resistors, and a microcontroller.
+{{< /imgproc >}}
+
+After some cleanup (and adding a fourth light) we get this nice little box:
+
+{{/*< imgproc "wiring.jpg" />*/}}
+{{/*< imgproc "finished.jpg" />*/}}
+
+## The code
+
+I tried to keep the code generic, but not too generic. I could have had the webhook server just record and relay
+an arbitrary string, for instance. But the server needs to be aware of 'momentary' switches, (for future ideas
+I have) and I want some sort of input validation, so instead the server expects a simple little json array.
+
+The client code currently only works on ESP8266 chips. (specifically, my prototype is an Adafruit Feather Huzzah)
+One 'fun' thing about the ESP8266, and more broadly Arduino programming in general, is that there are a lot of
+different libraries that can be used to achieve the same thing, with varying levels of ease and documentation. Getting
+HTTPS to work was surprisingly challenging, and I briefly went down a rabbit-hole of Arduino filesystems and hex-encoded
+CA certificates before discovering BearSSL's WiFiClientSecure library.
+
+The server code is [here](https://git.annabunch.es/annabunches/gpio-webhook-server) and the client code is
+[here](https://git.annabunch.es/annabunches/gpio-webhook-arduino).
+
+## Triggering the webhook
+
+Anything that can POST to a URL can be used to write to the webhook and change the light. I'm using [IFTTT](https://ifttt.com)'s
+Amazon Alexa integration, which seems to be the easiest way to get an Alexa to send a webhook.
+
+## Understanding the pin mapping
+
+The `PIN_MAP` variable in `config.h` needs to be configured based on the particular board you're using, and which GPIO pins
+you've decided to use for that board. As mentioned above, this project is using an Feather Huzzah with the ESP8266 chip.
+The pinout for that board looks like this:
+
+{{< imgproc pinout.png >}}
+Pinout diagram for Feather Huzzah ESP8266. Copyright Danny Nosonowitz. Original available [here](https://learn.adafruit.com/assets/46249").
+{{< /imgproc >}}
+
+I'm using the "bottom" four pins on the right-hand side, pins 4, 5, 2, and 16. So `PIN_MAP` looks like this:
+
+{{< highlight C >}}
+{
+  {4, 1}, // green
+  {5, 1}, // yellow
+  {2, 1}, // red
+  {16, 1} // blue
+};
+{{< /highlight >}}
+
+The order in this array determines which pin maps to each webhook data point. For example, if the webhook data received looks like `[1,0,1,0]`, that would turn on the green and red lights.
+
+## Security Concerns
+
+Don't use this code for anything critical! The only protection this has against malicious input is the webhook
+URL being kept a secret. Assuming your webhook server is either kept on your local network or secured behind an HTTPS proxy,
+that should be a reasonable guarantee, but it's still a fairly shaky amount of security. I considered requiring POST requests
+to be signed by a secret certificate of some sort, but that would rule out using something as simple as IFTTT to send the webhooks. So instead,
+I've sacrificed a measure of security for ease of use.

layouts/shortcodes/imgproc.html

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+{{ $original := .Page.Resources.GetMatch (printf "*%s*" (.Get 0)) }}
+{{ $imgdata := imageConfig (printf "/content/%s" $original.RelPermalink) }}
+{{ if (gt $imgdata.Width 1500) }}
+  {{ .Scratch.Set "image" ($original.Resize "1500x") }}
+{{ else if (gt $imgdata.Height 1500) }}
+  {{ .Scratch.Set "image" ($original.Resize "x1500") }}
+{{ else }}
+  {{ .Scratch.Set "image" $original }}
+{{ end }}
+
+{{ $image := .Scratch.Get "image" }}
+
+<figure style="padding: 0.25rem; margin: 2rem 0;">
+  <a href="{{ $original.RelPermalink }}">
+	<img style="max-width: 100%; width: auto; height: auto;" src="{{ $image.RelPermalink }}" width="{{ $image.Width }}" height="{{ $image.Height }}">
+  </a>
+	<figcaption>
+	  {{ .Inner | markdownify }}
+	</figcaption>
+</figure>  

layouts/shortcodes/raw.html

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+{{.Inner}}