I had one of these lying around the house. It was bought for the windows and doors, but it was never used at my place. Operation The white package next to the alarm is a magnet, so this indicates that the alarm is operated by a reed-switch. When the door is opened, the magnet will move further away from the alarm. The changing magnetic field is detected by the alarm, and it starts a countdown. When the password is typed in, the countdown stops. If it is not typed in before the countdown completes, the alarm will buzz. ...

This error was frustrating to fix but turned out it was a teensy tiny error of my own. Context I was attempting to send a struct over a radio on Arduino struct State { int x; int y; }; struct State MyState; .... radio.send((uint8_t *)&MyState, sizeof(struct MyState)); So I tried to get the size of an instance instead of the struct itself. No wonder Arduino complained that it couldn’t find the struct with the error message of: invalid application ... to incomplete type 'loop()::MyState'. ...

This is how I hooked up an ST 7735 TFT LCD module to an Arduino. This is a small, cheap screen with color display, and an excellent Adafruit library has already been written for it, making it a breeze to use. I recently purchased a TFT screen with the intention of using it eventually. However the markings on the back confused me a little. These are the mappings from the generic red SPI TFT to the Adafruit breakout. ...

After messing around with the nRF52 for a little while, one day I wondered if there was a cheaper option for bluetooth modules, because all I really wanted was the Bluetooth from the nRF52. It took awhile to look, but I was not disappointed. I found the CC2541. Introduction HM-11 modules have been floating around for a very long time. Their latest claim to fame is their enlistment as credit card skimmers, as documented on Sparkfun’s investigation. I encourage you to read it, it is quite detailed and fascinating. ...

Tl;dr, don’t power Arduino Pro Mini Clones with 12V. You will see smoke. I was attempting to rebuild my Sunrise alarm clock with an Arduino Pro Mini. However when I plugged in my 12V supply, a capacitor exploded on the board. The brown bit that you see near the bottom of the board was the component that sparked, and then started to smoke. It smelt like solder. I pulled out the power supply, but I think the board is ruined. ...

A little desk thingy that can report the weather outside and serve as a Pomodoro timer. I call it the Able Stable. Background I often find myself checking on the weather before I go out. Sometimes the weather can be bitterly cold, and other times it can be warm enough to stroll in, but it is hard to tell just by looking out of the window. Since I work at my desk most of the time, it is useful to have productivity enhancing tools such as a Pomodoro timer nearby. ...

A guide to getting started in hobby electronics in 2018. Motivation For some time now I’ve been thinking about how they should get started in electronics. It is easy to point them to Arduino and say, start there, and that is what many guides do. But beyond blinking an LED, it is sometimes hard to suss out what to do next. I think that it quickly turns people off if they aren’t able to building something interesting. I certainly understand wanting to get results quickly. A lot of electronics that I play with is just for hobby and fun, so if I’m going to spend my precious leisure time on something, it shouldn’t take a week to bear fruit on my first project. ...

This is a teardown of the IKEA TVÄRS lamp and provides two small but fun projects you can do with this very versatile, very affordable lamp from IKEA: a controllable RGB lamp and a lit charging station. Disassembling this lamp is pretty simple! First unclip the bulb holder from the base as follows (the wire was already removed in this case): Next using needle nose pliers, reach in and grip the contacts and pull. The contacts will bend a little, and then pop out. ...

Fixing Jlink DLL issues with nRFgo Studio This post serves as a collection of help tutorials that I found useful when getting started with the nRF52. Related: Jlink not detected in nRFgo Studio, Failed to find JLINK dll. Had a spot of trouble fixing this one. However, uninstalling everything and reinstalling everything made it work again. How to fix Uninstall Nordic, Jlink, Segger software Remove all registry keys of Nordic, Jlink or Segger software using regedit ...

Towards Better Biking Safety Background I met the excellent Signals team at Maker Faire Singapore in July. They were developing the product The Official Signal. Figure 1. The Official Signal It appears to be a motion-sensing bike attachment. From what I could tell the detection was based on detecting a spike in acceleration when the user turns their head, and this turns on the light. While they were not able to share the details of their platform with me because it was proprietary, I did gain a few important ideas from talking to them. ...