In the physical layer of the Bluetooth protocol stack, there are two useful parameters: LQI and RSSI. Both are used by the receiver to evaluate the current wireless environment quality (link quality) and guide subsequent actions. However, the calculation principles and application scenarios of these two values differ significantly. LQI (Link Quality Indication) measures the quality of the received signal. The quality of the received signal is estimated by the receiver by comparing the received signal with the ideal signal and calculating the error accumulation value.

A few months ago, I discovered the oddly-named JavaScript library “bacon.js”. Essentially, it lets you declare and compose event channels. While it seems overly abstract, the sample code intrigued me, as it introduced me to what is called “reactive programming”. Let’s put this in context of typical UI programming. Let’s say you want to write a GUI with a button that initiates a file download. You can’t simply make the download synchronous, as it would “freeze” the entire GUI.

Smart cards have become an indispensable part of our daily lives, used in various applications such as finance, transportation, and identity verification. At the heart of smart card technology lies the Secure Element (SE) and the 7816 protocol, which together form the foundation of security and reliability. In this blog post, we will delve into the history, application scenarios, technical details, and implementation methods of SE and 7816 protocol. Secure Element (SE) Definition A Secure Element (SE) is a microprocessor chip specifically designed for security applications, used in smart cards, mobile devices, and other electronic devices.

As computer communication professionals, we are well aware of the significance of wireless communication protocols in today’s connected world. Among the numerous wireless protocols available, Zigbee has emerged as a popular choice for low-power, low-data-rate applications. In this blog post, we will delve into the details of the Zigbee protocol, its architecture, and how to implement a Zigbee-based network. What is Zigbee? Zigbee is a low-power, low-data-rate wireless communication protocol based on the IEEE 802.

Last weekend brought an interesting challenge: to create a remote-controlled, small-sized dry ice “fog” dispenser for a company event. In the end it wasn’t used, but I had a lot of fun building it anyway. Here is how it was done: Hardware Fog machines usually heat dry ice (solid CO₂) pellets with hot water. Its sublimation produces a very convenient fog: mostly harmless for humans, leaves no residue and won’t float (therefore not triggering fire alarms).

As part of my “spring cleaning”, and partly inspired by this “Earth Hour” thing, I did an inventory of all the connected electrical devices around my apartment. I basically categorized them this way: Devices that are used all the time and must be connected: Lights, electrical heating, fridge, water heater and so on. Devices that are seldom used, but cannot be turned off completely or disconnected easily: Oven, washer, dryer, and so on.

As the Internet of Things (IoT) continues to grow, the need for efficient and reliable data transfer between devices has become increasingly important. One approach to achieve this is by emulating the Universal Serial Bus (USB) protocol over Bluetooth Low Energy (BLE) technology. In this blog, we will explore the concept of emulating USB protocol over BLE and provide a detailed implementation guide for computer enthusiasts. Introduction to BLE and USB

Even though you can plug a Raspberry Pi to any modern TV/monitor, its diminutive size screams for a smaller screen, ideally a touch-sensitive one. PiScreen was one of the first (relatively) inexpensive screens like that. Excited by the video below, I backed its KickStarter in April, received it in October and just found the time to build it. https://youtu.be/sM0-iksBXDc I had some fun, and I will still do some interesting stuff with it.