https://community.element14.com/challenges-projects/project14/Monthly Electronics & Design Project Competitions. Build projects around themes, submit video proof, and win free products regardless of level of expertise.en-USTelligent Community 12https://community.element14.com/challenges-projects/project14/b/show-and-tell/posts/from-reichspost-to-iot-reborning-a-wwii-vintage-phone-with-esp32-gsmWed, 05 Aug 2026 19:51:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:9a5aab6c-bd5c-4c98-b2ed-b823644c2346saturn_ringsThe inspiration Let's be honest, our grandparents hate smartphones. They find it hard to navigate through menus, forget where the emergency button is, and often want nothing to do with modern technology. On top of that, the world is full of electronic waste. That's where the idea came from: why not kill two birds with one stone? My bachelor's thesis professor gave me this telephone to restore; although its exact model remains unconfirmed despite historical research, engraved codes on the components indicate it was standardized by the Reichspost (RP), possibly pointing to a Siemens & Halske Ortsbatterie desk phone from 1933 that used a local battery system and a side-mounted magneto crank instead of a rotary dial. I took an old telephone from the World War II era and gave it a second chance. The main idea was to build an emergency device where seniors or vulnerable people don't have to learn anything new, they use the exact classic gesture they grew up with: picking up the receiver from the hook. This project started as my bachelor's thesis. How it works On the outside, the classic look was preserved, but on the inside, some microcontrollers were inserted to implement an emergency logic. There's no need to touch screens or search for contacts. When someone has an emergency, they have two super simple options: either pick up the receiver (detected instantly by a microswitch hidden in the hook mechanism) or just say "Help" (voice command). What happens next? The second the alarm is triggered, the LilyGO T-Call (ESP32 + SIM800L) board springs into action: It talks to nearby cell towers to grab its coordinates via the GSM network. It automatically sends a message on Telegram with a direct Google Maps link so the family knows exactly where the person is. It places a direct emergency phone call straight through the SIM card. Step-by-Step implementation guide Step 1 - hardware assembly & retrofitting: cleaning and restoring the vintage telephone chassis, painting it with a rugged hammer-tone finish, and adapting a custom microswitch onto the receiver's hook mechanism to capture physical lifting. Step 2 - The processing & communication core & audio/visual feedback: inside the shell, I mounted the LilyGO T-Call board (which packs an ESP32-WROVER-B and a SIM800L module together), a 2-inch TFT ST7789 display, a voice-command subsystem (powered by a Raspberry Pi 4 and an Adafruit PyBadge), an external antenna, and a Li-Po battery. To keep track of what's happening, the display was used to indicate all the states the board goes through, from initialization and operator detection to network searching and placing the call. Additionally, to give the user instant audio feedback, I added an active buzzer. It chirps during critical moments (like confirming that an emergency alarm has been triggered) and, even better, it mimics a traditional dial/ring tone while the emergency call is active so the user knows the call is going through. Step 3 - firmware & cellular positioning: writing the Arduino-based firmware using a finite-state machine logic to query tower parameters sequentially (AT+CCED, AT+CENG, AT+CREG=2) for cellular triangulation. Step 4 - cloud & Telegram integration: executing HTTPS POST requests to the Google Geolocation API and utilizing the Telegram Bot API to dispatch formatted Markdown emergency messages. What the Telegram message contains: Source field: the structure of this message stays identical whether triggered by voice or the hook-switch, only the source field changes. Timestamp & Location: shows the exact date, time, and coordinates with estimated precision. Google Maps Link: a valid, clickable link opening the exact pin on Google Maps. GSM Tower Data: MCC & MNC: identifies the country (Romania - 226) and operator (Vodafone - 01), LAC defines the zone group of cell towers, while Cell ID is the unique identifier of the specific tower antenna used for connection, and the signal who shows the network signal strength at activation. Step 5 - Voice command subsystem: training a custom voice-recognition model to detect the trigger word "Help", allowing the system to initiate an emergency alert hands-free alongside the physical hookswitch. The voice module was developed by another colleague. In collaboration, I developed a way to integrate it inside my project. Interesting Challenges and Workarounds Challenge 1 (AT command incompatibility): the primary command initially planned for data extraction (AT+CCED) was not supported by the SIM800L firmware version. Workaround: developed a cascading fallback algorithm that automatically switches to AT+CENG and AT+CREG=2 to reliably extract network parameters under any condition. Challenge 2 (rural geolocation accuracy): testing in rural areas revealed long distances between cell towers, resulting in coverage radio over 6 km and position errors around 1 km. Workaround: thoroughly documented this physical limitation of Cell-ID technology and proposed upgrading to a native GPS module (like the LilyGO T-SIM7000G) for future iterations. Challenge 3 (voice recognition reliability): voice triggers proved inconsistent in noisy real-world environments. Workaround: by testing different thresholds for the voice recognition method, a 70% accuracy has been achieved, taking into account that only an analog microphone could be installed on the Adafruit microcontroller; a better microphone would achieve better results. Current project status & remaining challenges What is working right now: the hardware restoration of the vintage telephone housing is complete, the mechanical hook switch and audio feedback (buzzer) are fully functional, and the core emergency loop, fetching cellular data and dispatching a Telegram alert with a Google Maps link, works reliably in covered areas. Remaining challenges & the next-gen dissertation plan: right now, the project is a solid prototype, but the journey doesn't stop here. For my dissertation project, I am currently working on scaling and expanding this architecture to make it truly smart and medical-grade. The remaining challenges and upcoming upgrades include: mmWave Radar Integration: hiding a millimeter-wave (FMCW) radar sensor inside the vintage casing to provide non-contact, automated fall detection and continuous health monitoring for seniors. TinyML Audio Analysis: implementing an on-device Machine Learning model running directly on the ESP32 using TinyML to classify distress sounds (like cries for help or breaking noises) acoustically. Hyper-Local Geolocation: tackling the rural positioning error (~1000m) by fusing raw GSM cell-tower data with nearby Wi-Fi network scanning through the Google Geolocation API, aiming to bring accuracy down under 150 meters. If you have any other ideas for future improvements, feel free to share them! Thank you for taking the time to read about my project, and if you want to find out more or discuss it further, feel free to drop me a message anytime!https://community.element14.com/challenges-projects/project14/b/show-and-tell/posts/compact-rpi-cm4-based-home-assistant-systemTue, 04 Aug 2026 05:03:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:37781cd2-4256-4b61-bb72-d944056018feralphjyIntroduction I'm currently waiting to receive the hardware for the Raspberry Pi Compute Module 5 Development Kit RoadTest . My motivation for applying for that roadtest is to replace a Home Assistant (HAOS) home automation system that I have running on an RPi4. My present system runs HAOS with a Frigate NVR add-on and a Coral USB AI accelerator. During last winter's storms we had multiple power outages that caused corruption of the system SD card multiple times and I decided that I'd like to go with faster and more persistent (reliable) storage like the eMMC flash storage available on a compute module. In assessing my existing function partitioning, I decided that I would take this opportunity to reorganize my system configuration. Here are diagrams of my existing setup and my restructured one. My existing setup evolved over time. I originally had a requirement to create local dashboards for my environment sensors (temperature, humidity), so I started using an RPi4 with Node-Red and MQTT for messaging. Then I added database and graphing capability for analysis. Later I wanted a home automation tool that I could use to aggregate control for switches and lights from the various vendors and their apps, so I added another RPi4 flashed with Home Assistant (HAOS). Then I wanted to add object detection and storage for my security cameras, so I added the Frigate add-on to Home Assistant. Then I added a Coral USB AI accelerator to improve detection performance. One thing that I learned from this setup is that I had difficulty adding more than a couple of cameras before it started to impact the operation of Home Assistant. Therefore, I will partition the new setup with a CM5 dedicated to running Frigate (this is the RoadTest kit). And use a separate CM4 for HAOS and the other utilities (Node-Red, etc) will be HA add-ons. The CM4 setup is the subject of this Show&Tell project. RPi CM4 with HAOS CM4104032 Specification Details Processor Broadcom BCM2711 quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz Memory 4GB LPDDR4 Storage 32GB eMMC Connectivity Optional wireless LAN, 2.4GHz and 5.0GHz IEEE 802.11b/g/n/ac wireless, Bluetooth 5.0, BLE with onboard and external antenna options Onboard Gigabit Ethernet PHY supporting IEEE1588 1 × USB 2.0 interface PCIe Gen 2 x1 interface 28 GPIO signals SD card interface for SD card or external eMMC Video Dual HDMI interface (up to 4Kp60 supported) 2-lane MIPI DSI display interface 2-lane MIPI CSI camera interface 4-lane MIPI DSI display interface 4-lane MIPI CSI camera interface Multimedia H.265 (4Kp60 decode); H.264 (1080p60 decode, 1080p30 encode); OpenGL ES 3.0 graphics Input power 5V DC Operating temperature 0 to +80°C Dimensions 55 mm × 40 mm Waveshare CM4-Nano-B Carrier Board I am using a Waveshare Carrier that has the same footprint as the CM4 to provide a very compact assembly. 3D printed enclosure with CM4+Carrier+Heatsink I found a 3D file on Thingiverse, PI_CM_WS_nano_b_case.stl, that I could use with with the carrier board and passive heatsink. I am not doing any heavy computational work, so the passive heatsink should be fine (might not even be needed). When I was running HAOS with Frigate I used active cooling with a heatsink and fan. I hadn't intended to post this project until I saw the Show&Tell competition, so I don't have the disassembled view (it's a snap fit in the enclosure which makes it somewhat difficult to easily take it apart once the heatsink is added). Below are pics of the ports on the case. Top view looking down at the heatsink Yellow cable is Ethernet (using it rather than WiFi for improved reliability) White cable is USB-C power (using 5V 3A RPi power adapter) uFL WiFi antenna connector is available but not used Bottom view 40p GPIO connector CSI connector DSI connector Side view Mini HDMI connector USB-A host connector Latch to hold assembly in case Side view Ethernet RJ-45 connector USB-C power connector SD card socket above USB-C (easier to see in next pic) Side view Audio jack Boot switch Side view User button Home Assistant HAOS Installation The good news is that the Raspberry Pi Imager can be used to flash HAOS onto the eMMC card. There's a couple of extra steps involved because we are writing eMMC rather than an SD card. There is an additional usbboot (rpiboot) utility required to expose the eMMC as a normal drive for writing. You also need to set the Boot switch on the carrier board for this mode. The instructions are straightforward and I did not have any issues. The one caveat is that the USB-C port is being used to both power and flash the CM4 so the host computer port needs to have sufficient power or you'll need to add a powered USB hub. I used the USB3 port on a Windows desktop without any issues (rated at 900 mA). I won't go through all the setup and configuration steps as these are well documented. You are required to create a User account with name and password. And it is also necessary to install HACS (Home Assistant Community Store) to get Node-Red, InfluxDB, and Grafana. MQTT is a standard (official) add-on. Home Assistant Home Page Installed Apps CM4 Status (have to scroll down for processor and memory usage) Node-Red flow to mimic CM4 status on external dashboard The Deployed Dashboard at URL: http://homeassistant:1880/endpoint/dashboard/page1 Status of Sensors and Lights Project Summary Home Assistant is running with the required apps installed. I've just tried Node-Red, so there's more testing required to verify the other apps. The processor temperature is staying below 45 C with a 25 C ambient, so I'm confident that I don't need active cooling. I really like the small footprint. I think that I might add an audible alarm. Now need to wait for the CM5 RoadTest hardware to arrive to get Frigate running. I have a Hailo 8L M.2 AI accelerator that should give me a lot better performance at 13 TOPS vs the 4 TOPS of the Coral USB (I also have a Coral M.2 which is also rated at 4 TOPS, but should perform better than the USB). Unfortunately, the CM5 IO Board doesn't have room for a dual M.2 adapter, so I can't add an SSD drive. I'll need to see if I can find a fast USB drive.mqtthaoshome assistantraspberry pi cm4node-redRaspberry Pi CM5hailo 8frigate nvrhttps://community.element14.com/challenges-projects/project14/b/make-a-connection/posts/a-nut-itch-that-needed-scratchingSat, 01 Aug 2026 19:04:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:68dff1de-81d0-4f43-a942-755e353dba2dcolporteurI had an IT itch that I needed to scratch. The yard supervisor met me at the office with his phone, he stated, “We’re performing seed-plant maintenance and received this message.” He showed me a screenshot of the control computer for the plant. Immediately I responded, “You don’t have a network. Let me take a look and I will let you know.” All the golf carts used to ferry employees around the yard were gone. It was a walk or take my car the half kilometer to the seed-plant. How did I know it is half a kilometer? The point-to-point network elements that beam the network signal to that part of the yard indicate 600m. While walking to the building, I pondered what could be wrong. I had used the network monitoring system in the office to examine that part of the network and it showed the switch for the plant was offline. When I arrived, I discovered the network switch didn’t have power. This issue stemmed from the UPS being offline. The UPS was installed to prevent brownouts. The plant is at the far reaches of the yards AC power runs. Larger motors and industrial equipment powering up play havoc with the yard AC. Delicate equipment like computer had issues before the UPS was installed, frequent reboots or short network outages were normal. Why was the UPS off? That question remained unanswered. My itch to know if and when such things happens motivated me to find a way to communicate with the UPS. Of course, the vendor of the UPS had a solution. The UPS hardware was old so it didn't support the current solution. Looking through the archive there were some options. They had a cost that didn’t fit the budget. I had just done a spring cleaning and discovered a Raspberry Pi2B in a cardboard box. Why not build a UPS monitoring system? After some internet research, I discovered that my idea was not original. According to Wikipedia https://en.wikipedia.org/wiki/Network_UPS_Tools was developed 28 years ago, many contributors designed a NUT server. NUT (Network UPS Tools) is a software suite designed to monitor power devices. Here, I thought I had an original idea. Considerable software development occurred within the 28 years since the concept’s inception. At the home for NUT https://networkupstools.org/ I found an archive that dates back to May 2005. Low and behold if the nuts that look after the NUT didn’t share a release for July 2026. YES my NUT itch could be scratched! My communication project is still on track. OK for a BOM. I had a Pi2B with a 16M flash card and wall wart. The UPS equipment had a DB9 serial port and a USB 2.0 Type B connector. I call it a USB printer cable connector, since that is where I typically see that connector. I didn’t have a USB to DB9 serial cable. I had plenty of USB printer cables. I couldn’t seem to lose all the USB printer cables kicking around the office. All the printers installed use a network connection, and the printer cable supplied never got used. Got the software. Got the cable. Got the hardware. Let’s get communicating. To get my NUT itch scratched required drawing on some knowledge not included in the HOW-TO’s that I found on the internet. If someone in IT pairs the two words “it’s” and “easy” in a statement, the immediate response should be “for whom”. I’ve been playing in IT for almost half of my 40-year career in technology. Tips and tricks I’ve learned along the way came in handy to crack this NUT. sudo apt update #just built the pi so the ubiquitous setup commands sudo apt upgrade sudo reboot #my start from go command. It worked before does it work now. vcgencmd get_throttled #check that the pi doesn't have any power issues sudo apt install nut #install the Network UPS Tools package sudo nut-scanner -U #with the USB cable connected this gets information needed later sudo vi /etc/nut/ups.conf #the four configuration files that works for me. sudo vi /etc/nut/upsd.conf sudo vi /etc/nut/nut.conf sudo vi /etc/nut/upsmon.conf sudo reboot I judge the quality of a HOW-TO document on HOW-MUCH I need to change the HOW-TO in order to get the project working. I didn’t find one HOW-TO, that worked from start to finish. Gather nuts from each of the stashes of videos and Internet posts finally got my NUT working. Below I have provided screenshots or code for the four files that I added configuration details to get the NUT working. The Pi needs to communicate with the UPS hardware in order to configure the NUT server. The NUT software provides a tool nut-scanner -U to make that USB query possible. I’ve included a list MY-HOW-TO commands and the files to get a working NUT server, apc-seedplant. Note the software version reference points for this working NUT. Changes in the operating system, software packages, and the NUT software itself can move the dependencies so that things don’t work. Hardware: Description : Raspberry Pi 2B rev 1.1 RAM : 1GB Storage : MicroSD 16G Software: Raspberry Pi OS Lite System 32-bit PRETTY_NAME="Raspbian GNU/Linux 13 (trixie)" Release date 18 Jun 2026 nut-server 2.8.1-5 sudo cat /etc/nut/ups.conf Recall you queried the UPS for information. This is the file where that information goes. I just drop to the bottom of the file and start entering. sudo cat /etc/nut/upsd.conf Setting up port requirements. sudo cat /etc/nut/nut.conf You will find the MODE line inside this file. In mine it had , I changed it to this value. MONITOR apc-seedplant@localhost 1 upsadmin BN11ooM2-C@ primary RUN_AS_USER root MINSUPPLIES 1 SHUTDOWNCMD "/sbin/shutdown -h" NOTIFYCMD /usr/sbin/upssched POLLFREQ 2 POLLFREQALERT 1 HOSTSYNC 15 DEADTIME 15 POWERDOWNFLAG /etc/killpower NOTIFYMSG ONLINE "UPS %s on line power" NOTIFYMSG ONBATT "UPS %s on battery" NOTIFYMSG LOWBATT "UPS %s battery is low" NOTIFYMSG FSD "UPS %s: forced shutdown in progress" NOTIFYMSG COMMOK "Communications with UPS %s established" NOTIFYMSG COMMBAD "Communications with UPS %s lost" NOTIFYMSG SHUTDOWN "Auto logout and shutdown proceeding" NOTIFYMSG REPLBATT "UPS %s battery needs to be replaced" NOTIFYMSG NOCOMM "UPS %s is unavailable" NOTIFYMSG NOPARENT "upsmon parent process died - shutdown impossible" NOTIFYFLAG ONLINE SYSLOG+WALL+EXEC NOTIFYFLAG ONBATT SYSLOG+WALL+EXEC NOTIFYFLAG LOWBATT SYSLOG+WALL NOTIFYFLAG FSD SYSLOG+WALL+EXEC NOTIFYFLAG COMMOK SYSLOG+WALL+EXEC NOTIFYFLAG COMMBAD SYSLOG+WALL+EXEC NOTIFYFLAG SHUTDOWN SYSLOG+WALL+EXEC NOTIFYFLAG REPLBATT SYSLOG+WALL NOTIFYFLAG NOCOMM SYSLOG+WALL+EXEC NOTIFYFLAG NOPARENT SYSLOG+WALL RBWARNTIME 43200 NOCOMMWARNTIME 600 FINALDELAY 5 sudo cat /etc/nut/upsmon.conf Lots of stuff to enter in this file so I flipped presentation to code to support cut and paste. This is not a tutorial on the NUT server. Therefore I have omitted the details of the settings and purpose. The NUT site has the documentation if you wish to delve deeper. What does the NUT do for me? The NUT is physically on top of the UPS, quietly communicating over the network what the USB port tells it about the condition of the UPS. It is logging that data to disk (i.e. SD card). The NUT communicates the condition of the past and the present. Of course there has been no power outage lately to look at my NUT. sudo systemctl status nut-server #is the NUT active and running sudo systemctl restart nut-server #command to restart the NUT server when needed systemctl list-units | grep nut #get a look at what is in NUT journalctl -u nut-driver@apc-seedplant.service #service tell me what you have logged. journalctl -u nut-server #service tell me what you have logged. journalctl -u nut-monitor #service tell me what you have logged. upscmd -l apc-seedplant #cli tool to send commands to your UPS via the upsd server. upscmd -u upsadmin -p BN11ooM2-C@ apc-seedplant test.battery.start.quick upsc apc-seedplant #read-only cli command for the upsd server to provide UPS status upsc apc-seedplant battery.runtime Above is a list of commands to poke around the NUT server. Again there are little details for a fuller understanding of the commands. The communication contest caught my eye; I wanted to take part, but I was not working on any electronic bits and bobs at the moment to fashion an entry. Then I broadened my understanding of communicating. E14 community is all about communicating. Folks share their creations with others. Those shares have brought me success. I use the community as a knowledge repository. I returned to locate my project specifics; I can’t recall. Then I got a NUT itch that I could communicate about it communicating.network monitoringraspberry piusb communicationhttps://community.element14.com/challenges-projects/project14/b/show-and-tell/posts/plc-with-psocTue, 28 Jul 2026 11:38:00 GMT93d5dcb4-84c2-446f-b2cb-99731719e767:12478b15-2b8a-41c6-b77e-e43c458379f3Em0keThis PLC board is designed using a Cypress System-on-Chip (SoC) microcontroller for industrial automation and embedded control applications. The Cypress SoC integrates a microcontroller with programmable analog and digital peripherals on a single chip, making the system compact and efficient. The PLC is capable of monitoring multiple digital input signals and controlling several relay outputs according to the programmed logic. The relay outputs provide electrical isolation, allowing the board to safely switch external loads such as motors, lamps, solenoid valves, and contactors. Input and output connections are made through terminal blocks, making installation and maintenance simple. Driver ICs on the board interface the microcontroller with the relays to ensure reliable operation. LEDs indicate the status of the power supply and relay outputs, helping users monitor the system during operation. The DIP switch can be used to configure different operating modes or system settings. The PCB layout is compact and integrates the controller, relay drivers, relays, and supporting components on a single board. The Cypress SoC executes the control program stored in its memory and processes input signals in real time. This PLC is suitable for industrial process control, machine automation, and educational projects. Its flexible architecture allows new control functions to be added through software without major hardware modifications. The combination of reliable hardware and programmable control makes the system versatile and cost-effective. Overall, this PLC demonstrates how a Cypress System-on-Chip microcontroller can be used to develop a reliable, efficient, and flexible industrial control system.