Added blog entry for RFID door control

input/blog/2019/2019_06_20_rfid.md

@@ -0,0 +1,39 @@
+title: Blog
+post: Arduino RFID door lock
+date: 2019-06-20
+comments: true
+github: https://git.xythobuz.de/thomas/RFID-Door
+---
+
+## {{ page["post"] }}
+<!--%
+from datetime import datetime
+date = datetime.strptime(page["date"], "%Y-%m-%d").strftime("%B %d, %Y")
+print "*Posted at %s.*" % date
+%-->
+
+To avoid unwanted access to my old room, I saw the need to install some kind of additional door lock mechanism.
+After taking a look around my parts-bin, I've settled on an RFID-based solution.
+
+Luckily I still had a [serial RFID antenna from Conrad (TowiTek TWT2021)](https://www.conrad.com/p/rfid-antenna-towitek-twt2021-component-33-vdc-5-vdc-191553) lying around.
+It simply outputs the ID of a transponder in reach on a serial output with 9600 baud as ASCII string.
+
+Combined with a cheap [door-lock-solenoid from Amazon](https://www.amazon.de/gp/product/B00M2M3F74), a [relais-board](https://www.amazon.de/WINGONEER-KY-019-Relais-Shield-Arduino/dp/B06XHJ2PBJ) and a power-supply the project was basically completed.
+To easily allow opening the door from the inside, I've added a small push-button that triggers the solenoid to the door-handle.
+
+The code can be found [on my Gitea-Server](https://git.xythobuz.de/thomas/RFID-Door).
+
+<div class="lightgallery">
+    <a href="img/rfid_box.jpg">
+        <img src="img/rfid_box_small.jpg" alt="">
+    </a>
+    <a href="img/rfid_setup.jpg">
+        <img src="img/rfid_setup_small.jpg" alt="">
+    </a>
+    <a href="img/rfid_button.jpg">
+        <img src="img/rfid_button_small.jpg" alt="">
+    </a>
+    <a href="img/rfid_solenoid.jpg">
+        <img src="img/rfid_solenoid_small.jpg" alt="">
+    </a>
+</div>