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diff --git a/_site/log/fpm-door-lock-rf/index.html b/_site/log/fpm-door-lock-rf/index.html deleted file mode 100644 index 55675ff..0000000 --- a/_site/log/fpm-door-lock-rf/index.html +++ /dev/null @@ -1,125 +0,0 @@ -<!DOCTYPE html> -<html> - <head> - <meta charset="utf-8"> - <meta name="viewport" content="width=device-width, initial-scale=1"> - <title>Fingerprint door lock (RF)</title> - <link rel="stylesheet" href="/assets/css/main.css"> - <link rel="stylesheet" href="/assets/css/skeleton.css"> -</head> - - - <body> - - <div id="nav-container" class="container"> - <ul id="navlist" class="left"> - - <li > - <a href="/" class="link-decor-none">hme</a> - </li> - <li > - <a href="/projects/" class="link-decor-none">poc</a> - </li> - <li > - <a href="/about/" class="link-decor-none">abt</a> - </li> - <li> - <a href="/cgi-bin/find.cgi" class="link-decor-none">lup</a> - </li> - <li> - <a href="/feed.xml" class="link-decor-none">rss</a> - </li> - </ul> -</div> - - - - <main> - <div class="container"> - <div class="container-2"> - <h2 class="center" id="title">FINGERPRINT DOOR LOCK (RF)</h2> - <h5 class="center">05 JUNE 2025</h5> - <br> - <div class="twocol justify"><p>Wanted to unlock door with fingerprint, wirelessly to avoid drilling.</p> - -<p>2024-11: Started with basic 433MHz RF modules and two Arduinos. Connected data -lines of the transceivers to UART RXD/TXD of an ATmega328P. -Unreliable–constant packet loss.</p> - -<p>2025-01: Switched to RFM69 modules. Complete ball-ache. Followed datasheet to -the letter, audited code many times, cross-checked with RadioHead and RFM69 -open-source drivers. No luck.</p> - -<p>Datasheet riddled with ambiguity.</p> - -<p>ATmega328P runs at 5V; RFM69 3.3V. Suspect logic-level converter (LLC) -issues. High resistance. Not enough swing.</p> - -<p>2025-04: Ditched RFM69s. Switched to NRF24L01+ modules– data pins 5V tolerant, -no LLC required. Spent six weekends writing driver from scratch–clean-room. -Works like a charm.</p> - -<p>2025-05: Wrote FPM drivers for R503 and FPM10A. UART RX sequence was -tricky–adopted Adafruit C++ FOSS implementation to C. R503 has built-in LEDs -and better form factor. Chose it for the lock.</p> - -<p>2025-06: Two PCB boards for FPM (front) and servo (back) controllers. Encrypted -RF link between them.</p> - -<table style="border: none; width: 100%"> - <tr style="border: none;"> - <td style="border: none; width: 49.5%; vertical-align: top; text-align: center;"> - <img src="front_design.jpeg" alt="Design (front)" style="width: 100%" /> - <p>Footprint (front)</p> - </td> - <td style="border: none; vertical-align: top; text-align: center;"> - <img src="front.jpeg" alt="PCB (front)" style="width: 100%" /> - <p>PCB (front)</p> - </td> - </tr> - <tr style="border: none;"> - <td style="border: none; width: 49.5%; vertical-align: top; text-align: center;"> - <img src="back_design.jpeg" alt="Design (back)" style="width: 100%" /> - <p>Footprint (back)</p> - </td> - <td style="border: none; vertical-align: top; text-align: center;"> - <img src="back.jpeg" alt="PCB (back)" style="width: 100%" /> - <p>PCB (back)</p> - </td> - </tr> -</table> - -<p>PCB specs: 2-layer, 1oz copper, 0.3mm traces (0.5mm for power). Ground plane.</p> - -<p>2025-06: NRF24L01+ on the back stopped working after mounting on PCB. Too close -to servo’s PWM line. Soldering a large 47uF (16V) electrolytic capacitor -between VCC and ground fixed it.</p> - -<p>Power problems became clear. Linear regulators dissipated too much heat. Sensor -and servo drew 13.8mA and 4.6mA quiescent currents–unacceptable for battery. -Servo inrush current exceeds 1A. 0.3mm tracks cuts it too close.</p> - -<p>Verdict: Functional but not practical. Battery dead in under 24 hours. Led to -<a href="../fpm-door-lock-lp/">redesign</a> with proper power management.</p> - -<p>Commit: -<a href="https://git.asciimx.com/smart-home/commit/?id=f4b0b734a595919cf451ab9448b06274c8e609a4">f4b0b73</a> -| Gerber: <a href="gerber_back.zip">gerber_back.zip</a>, -<a href="gerber_front.zip">gerber_front.zip</a></p> -</div> - <p class="post-author right">by W. D. Sadeep Madurange</p> - </div> - </div> - </main> - - <div class="footer"> - <div class="container"> - <div class="twelve columns right container-2"> - <p id="footer-text">© ASCIIMX - 2026</p> - </div> - </div> -</div> - - - </body> -</html> |