LimeSDR Mini – Software-defined-radio card

An open, full-duplex, USB stick radio for femtocells and more.

The LimeSDR and LimeSDR Mini are members of the same family of software-defined radios. One does not replace the other. Rather, they are complementary.

Simply put, the LimeSDR Mini is a smaller, less expensive version of the original LimeSDR. However, it still packs a punch – at its core, the LimeSDR Mini uses the same LMS7002M radio transceiver as its big sibling. The Mini has two channels instead of four, and, by popular demand, SMA connectors instead of micro U.FL connectors. Check out the comparison table below for more details.

LimeSDR Mini – Software-defined-radio card – [Link]

Fennec: LoRa Development Board

An ultra low power LoRa sensor node powered by just one CR2032 batter. By Harm Wouter Snippe:

Do you want to measure temperature, connect a soil humidity sensor in your vegetable garden or monitor the air quality at your street corner? With the Fennec Development Board you are able to connect almost any sensor and create your own amazing ultra low power wireless projects. We have created the most energy efficient Arduino compatible IoT device with LoRa communication in the world. Powered by only a button cell you can send sensor readings every 15 minutes for the next five years over long distances (5-15km).

New Ultrathin Semiconductors Can Make More Efficient and Ten Times Smaller Transistors Than Silicon

The researchers at Stanford University have discovered two ultrathin semiconductors – hafnium diselenide and zirconium diselenide. They share or even exceed some of the very important characteristics of silicon. Silicon has a great property of forming “rust” or silicon dioxide (SiO2) by reacting with oxygen. As the SiO2 acts as an insulator, chip manufacturers implement this property to isolate their circuits on a die. The most interesting fact about these newly discovered semiconductors is, they also form “rust” just like silicon.

enlarged cross-section of an experimental chip made of ultrathin semiconductors
An enlarged cross-section of an experimental chip made of ultrathin semiconductors

The new materials can also be contracted to functional circuits just three atoms thick and they require much less energy than silicon circuits. Hafnium diselenide and zirconium diselenide “rust” even better than silicon and form so-called high-K insulator. The researchers hope to use these materials to design thinner and more energy-efficient chips for satisfying the needs of future devices.

Apart from having the ability to “rust”, the newly discovered ultrathin semiconductors also have the perfect range of energy band gap – a secret feature of silicon. The band gap is the energy needed to switch transistors on and it is a critical factor in computing. Too low band gap causes the circuits to leak and make unreliable. Too high and the chip takes excessive energy to operate and becomes inefficient. Surprisingly, Hafnium diselenide and zirconium diselenide are in the same optimal range of band gap as silicon.

All this and the diselenides can also be used to make circuits which are just three atoms thick, or about two-thirds of a nanometer, something silicon can never do. Eric Pop, an associate professor of electrical engineering, who co-authored with post-doctoral scholar Michal Mleczko in a study paper, said,

Engineers have been unable to make silicon transistors thinner than about five nanometers, before the material properties begin to change in undesirable ways.

If these semiconductors can be integrated with silicon, much longer battery life and much more complex functionality can be achieved in consumer electronics. The combination of thinner circuits and desirable high-K insulation means that these ultrathin semiconductors could be made into transistors 10 times tinier than anything possible with silicon today. As Eric Pop said,

There’s more research to do, but a new path to thinner, smaller circuits – and more energy-efficient electronics – is within reach.

Researchers Developed VO2 Based MEMS Mirror Actuator That Requires Very Low Power

A joint research by the US Air Force Research Laboratory Sensors Directorate and Michigan State University have developed micro-electromechanical systems (MEMS) actuator based on smart materials, specifically vanadium dioxide (VO2). In the room temperature, Vanadium dioxide exhibits the Mott transition. It is a not-well-understood phenomenon known to occur in transition metal chalcogenides and transition metal oxides.

VO2 Based Mott - MEMS Mirror Actuator
VO2 Based Mott – MEMS Mirror Actuator

The research team was able to use VO2 thin films for making complex mirror support structures to create a programmable tilting mirror. Transition-metal oxides like VO2 require little energy to drive the transition and less than more conventional actuation technologies. This enables implementation of transition-metal oxide based MEMS in battery powered and mobile devices.

When an input voltage of 1.1V is applied, the mirror platform achieves the maximum vertical displacement of 75 microns. The average power consumption per mirror actuator is 6.5mW and the total power consumption is 26.1mW for the entire device. The Mott-MEMS actuator mirror showed vertical movements and tilt angles of 75 micrometers and 5.5 degrees, respectively.

While testing, vanadium dioxide (VO2) displayed hysteric behavior or memory effect. That means the current response to externally applied electrical force is dependent on the previous response. Such behavior will let the researchers predict its response nature for certain electrical signals and they can program the actuators to generate different types of responses.

Nelson Sepulveda, a professor of electrical and computer engineering at Michigan State University, said in a statement issued by Wright-Patterson Air Force Base,

The actuation of such devices using smart phase-change materials represents a new operating principle that enables their programming and reduces power consumption.

The study opened a new door in the development of MEMS mirror actuation technology, which could incorporate the use of the hysteresis of smart materials like VO2 for programming tilt angles and vertical displacements in MEMS mirrors. The researchers are focusing on developing programmable MEMs mirrors and improving the design to achieve more precise control and larger movements.

SPI Isolation Board

The isolated SPI module is designed for applications, where SPI signals need to be transferred over longer distances than usually. It is based on Linear’s LTC6820. The board is designed as two layer stack-up, with GND plane on the bottom layer and signal traces and components at the top layer. Signals and power are supplied over standard 100mil (2.54mm) pitch IDC header.


  • Dimension: 40.005 mm x 30.099 mm (1.575″ x 1.185″)
  • 1 Mbps Isolated SPI Data Communication at 10m
  • 500 kbps Isolated SPI Data Communication at 100m
  • Galvanic Isolation Barrier using standard transformer (1500V)
  • Requires no software changes in most SPI systems
  • 3.5V to 15V power supply
  • SPI mode can be adjust via on-board jumpers
  • can act as Master or Slave (adjustable via jumper)
  • screw terminal for twisted pair cable (i.e. as in CAT5 Ethernet cable)

SPI Isolation Board – [Link]

20 Input AND Gate

SyncChannelBlog @ writes:

What to do when you have a partial reel of 74AHCT08 chips burning a hole in your pocket? Design a 20 Input AND gate of course.

20 Input AND Gate – [Link]

3 Phase AC Motor Controller

This project made using MC3PHAC from NXP Semiconductor. The project generates 6 PWM signals for 3 Phase AC Motor controller. It’s very easy to make professional VFD combining with Intelligent Power Module (IPM) or 3 Phase IGBT/MOSFET with Gate driver. The board provides 6 PWM signals for the IPM or IGBT Inverter and also brake signal. Also this board works in stand-alone mode and doesn’t require any software programming/coding.

The MC3PHAC is a high-performance monolithic intelligent motor controller designed specifically to meet the requirements for low-cost, variable-speed, 3-phase ac motor control systems. The device is adaptable and configurable, based on its environment. It contains all of the active functions required to implement the control portion of an open loop, 3-phase ac motor drive. One of the unique aspects of this board is that although it is adaptable and configurable based on its environment, it does not require any software development. This makes the MC3PHAC a perfect fit for customer applications requiring ac motor control but with limited or no software resources available.

Included in the MC3PHAC are protective features consisting of dc bus voltage monitoring and a system fault input that will immediately disable the PWM module upon detection of a system fault.

3 Phase AC Motor Controller – [Link]

Rechargeable Magnesium Batteries – Safer And Cheaper Than Li-ion Batteries

Researchers at the University of Houston reported in the journal Nature Communications the discovery of a new design that significantly improves the development of a battery based on magnesium. Magnesium batteries are considered as safe resources of power supply – unlike traditional lithium-ion batteries. They are not flammable or subject to exploding – but their ability to store energy is very limited. But the latest discovery of the new design for the battery cathode drastically increases the storage capacity.

Energy diagrams for the intercalation and diffusion of Mg2+ and MgCl+
Energy diagrams for the intercalation and diffusion of Mg2+ and MgCl+ in magnesium batteries

In order to make magnesium batteries, the magnesium-chloride bond must be broken before inserting magnesium into the host, and this is very hard to do. Hyun Deog Yoo, the first author of the paper, said,

First of all, it is very difficult to break magnesium-chloride bonds. More than that, magnesium ions produced in that way move extremely slowly in the host. That altogether lowers the battery’s efficiency.

The new battery technology stores energy by inserting magnesium monochloride into titanium disulfide, which acts as a host. By keeping the magnesium-chloride bond intact, the cathode showed much faster diffusion than traditional magnesium batteries.

The researchers managed to achieve a storage capacity density of 400 mAh/g – a quadruple increase compared with 100 mAh/g for earlier magnesium batteries. This achievement even overpowered the 200 mAh/g cathode capacity of commercially available lithium-ion batteries. Yoo, who is also the head investigator with the Texas Center for Superconductivity at UH, confirmed this fact.

The cell voltage of a magnesium cell is only 1V which is significantly less than a lithium-ion battery which has 3.7V cell voltage. Higher cell voltage and high cathode capacity made Li-ion batteries the standard. Li-ion batteries suffer from an internal structural breach, known as dendrite growth what makes them catch fire. Being an earth-abundant material, magnesium is less expensive than lithium and is not prone to dendrite growth.

The magnesium monochloride molecules are too large to be inserted into the titanium disulfide using conventional methods. The trick they developed is to expand the titanium disulfide to allow magnesium chloride to be inserted rather than breaking the magnesium-chloride bonds and inserting the magnesium alone. Retaining the magnesium-chloride bond doubled the charge the cathode could store. Yoo said,

We hope this is a general strategy. Inserting various polyatomic ions in higher voltage hosts, we eventually aim to create higher-energy batteries at a lower price, especially for electric vehicles.

More IoT with Compute Module 3 and Ubuntu Core OS

Canonical, the company behind Ubuntu, announced recently that its IoT OS, Ubuntu Core, is available on the Raspberry Pi Compute Module 3 – the general-purpose compute product from the Raspberry Pi Foundation. This OS, the smallest Ubuntu ever, is the perfect host operating system for IoT devices and large-scale cloud container deployments. Actually, the Raspberry Pi Compute Module 3 (CM3), is a micro-version of the Raspberry Pi 3. With its new features, it provides a simple and affordable single board computer.

In fact, this module is based on the Raspberry Pi 3 hardware, providing twice the RAM and roughly 10x the CPU performance of the original Module, launched in 2014. Even though CM3 is replacing the original Compute Module, but CM1 is still compatible with the new Compute Module IO Board V3, and remains available for sale.

CM3 takes care of the complexity of routing out the pins, the high speed RAM interface and core power supply. Also, it allows a simple carrier board to provide what is necessary for external interfaces and form factor. The module uses a standard DDR2 SODIMM form factor, sockets by several manufacturers, are easily available, and are inexpensive.

Software Defined Everything?

As a vision for Canonical, The CM3 with Ubuntu Core allows developers to create new IoT products and devices. As well as offering a potentially smaller and more efficient replacement for some devices that contain larger Raspberry Pi boards.

“Gaining official support for Ubuntu Core is highly significant for our Compute Module 3. It opens up a huge community of developers keen to leverage Ubuntu’s particular advantages in the IoT world; its resource-efficient footprint, versatility, and industry leading security benefits,” says Eben Upton, CEO at Raspberry Pi.

Finally, more comprehensive information on the Compute Modules is available in the this hardware documentation, and includes a datasheet and schematics. In addition, you can check this step-by-step tutorial to install Core OS on your Compute Module 3 by Ubuntu Developer.