A Busan-based company has been developing J.Flex, an advanced lithium-ion battery that is ultra-thin, flexible, and rechargeable for the past few years now. The company used terms like bend, roll, twist, scrunch, fold, flex to describe the battery. EJ Shin, head of strategic planning at Jenax says:
“What we’re doing at Jenax is putting batteries into locations where they couldn’t be before.” She goes on “we’re now interacting with machines on a different level from what we did before,”
The devices unveiled by Jenax includes a sensor-lined sports helmet developed by UK-based firm HP1 Technologies for measuring pressure and force of impact, a medical sensor patch designed in France that can be embedded in clothings, for monitoring a wearer’s heart rate, and wearable power banks in form of belts and bracelets for patients who continuously have to be hooked up to medical devices. Shin says:
“You don’t want to carry a big, bulky battery on your body all the time. It’s heavy, uncomfortable, and sticks out from your clothes that’s when you need very thin, flexible batteries.”
Nicholas Kotov, a professor of chemical engineering at the University of Michigan is of the opinion that such kind of batteries may one day power more than just wearables, He identifies unmanned aerial vehicles as one example. A flexible battery installed in the wings or landing gear of such a device could create more space in the body for other components.
J.Flex In Various Shapes
Jenax is not the only company developing flexible batteries. Companies like Panasonic, Samsung, and STMicroelectronics are developing flexible batteries of their own. But Jenax boasts of having “a higher degree of flexibility” compared with its competitors. To create flexible batteries, companies manipulate the components of a battery cell, which includes the cathode, anode, electrolyte, and membrane separator. According to Shin, the secret to its flexibility lies in
“a combination of materials, polymer electrolyte, and the know-how developed over the years.”
The J.Flex is made from graphite and lithium cobalt oxide, but its exact composition and architecture remain a secret. Jenax has more than 100 patents protecting its battery technology.
J.Flex can be sized to be as thin as 0.5 millimeters, which will fit suitably for sensors, and as tiny as 20 by 20 millimeters (mm) or as large as 200 by 200 mm. It has an operating voltage between 3 and 4.25 volts. Depending on the size, conventional batteries capacity varies from 10 mAh to 5 Ah, with close to 90 percent of this capacity remaining after 1,000 charge-discharge cycles. Each charge typically takes an hour. However, J. Flex’s battery life depends on how it’s used. According to Shin, a single charge can last for a month in a sensor, but wouldn’t last that long if the battery was powering a display.
Michigan’s Kotov says:
“Overall, I think it’s a very good battery.”
Michigan’s Kotov is developing electrolytes for flexible batteries made from lithium and zinc. He comments on the safety of J.Flex.
“The key [to safety] is to find good electrolytes or good ion-conducting membranes,” says Kotov.
Batteries can explode if their electrolytes are leaking out, or when the cathode and anode are in contact, as might be the case when you bend flexible batteries.
Due to this, Jenax developed a special semi-solid electrolyte. The new gel polymer will be incorporated into all J.Flex batteries this year. Shin says
“We went to one of the biggest causes of battery explosions and made it non-flammable.”
Jenax is setting up its first production line for the battery in South Korea by the end of 2020. Shin says this will make it cost-competitive with traditional lithium-ion batteries. Finally, shin says
“We’re changing the paradigm of batteries… They’re no longer a component you buy at the end of your product design. Instead, batteries are becoming one of the critical enabling technologies for the final product.”
The saying that “everything old is actually new again” finally became a reality for the Pro Micro board, as the popular Arduino compatible board gets revised with few additional features. The board that has been a favorite for about half a decade now received something of a great refresh, a Qwiic connector at the back and a USB Type-C at the front.
Speaking at the product launch, owner and creator of the Pro Micro board said that it is committed to adding a whole lot of improvement to its products “…we refuse to leave “good enough” alone – that’s why we’re adding to our line-up of Arduino compatible microcontrollers” says Sparkfun’s Xtopher.
According to them, even though the Qwiic Pro Micro board has the same size and overall functionality as the original Pro Micro board, the newly revised version has some features that the formal models lack.
“…the board is the same size as the original Pro Micro, but we shrunk down some components on the board and added a few more features, like as a reset button, Qwiic connector, USB-C and castellated pads (this makes it really handy for your custom keyboard creators).”
In order words, the Qwiic Pro Micro is just a Pro Micro with full USB functionality and ATMEGA32U4 on board.
The tiny little board runs at 5V/16MHz and cuts complexity by combining 3.3V and 5V operation on a single board. So with the Qwiic Pro Micro, there’s really no need to choose between 3.3V and 5V models. The board also has full compatibility with Arduino IDE and is capable of all the Arduino tricks you can think of.
Qwiic Pro Micro
Features include:
Nine 10-bit ADC pins
5 PWM pins (pulse Width Modulation)
12 Digital IOs, hardware serial connections Tx and Rx
Qwiic connector to add Qwiic enabled I2C devices to projects.
USB-C connector for programming
Reset regulator to quickly reset or place the board into the bootloader mode without having to use jumper wires
AP2112 3.3V regulator
Castellated pads
Meanwhile, the Qwiic Pro board can go just anywhere; the speed and power of the board make it great for small builds to go into the wild especially if you want to travel with them and packing size is a concern.
The board is available now at Sparkfun webshop for $19.95, slightly above the price of the 3.3V and 5V models that sells for $17.95.
App note from Vishay about how ESR in tantalum capacitors affects circuit performance. Link here (PDF)
When choosing a capacitor for any application, there are a few key characteristics that must be understood in order to analyze its suitability for the circuit. In a simple capacitor equivalent circuit model, there are three key characteristics that affect circuit performance: capacitance, equivalent series resistance (ESR), and inductance. The magnitude of these elements and how they change over temperature, frequency, and applied voltage are different for each capacitor technology.
Low ESR tantalum capacitors make a difference in circuit designs – [PDF]
The Debian based open-source Linux distribution Ubuntu finds its wide use across Desktop, Servers, Containers and now in IoT and cloud applications. Being very secure and its OpenStack support, it is further getting adapted widely in high end embedded computing applications as well.
iWave systems rich i.MX8 System on Module and SBC product portfolio is supported with Yocto Linux, Android and QNX BSP. Now iWave Systems is enabling the Bionic Beaver Ubuntu 18.04 LTS support to its latest i.MX8 Quad Max, Quad Plus and i.MX8M, i.MX8M mini system on Modules and SBC products.
Wayland support in the BSP brings better performance, code maintainability and security compare to X server. In Wayland, compositing is passive, which means the compositor receives pixel data directly from clients and hence it reduces the latency compared to the X server. The GUI with the Wayland Compositor on the iWave i.MX8 board is shown below;
Ubuntu 18.04 LTS – Google Chromium Bowser and Weston Terminal
Ubuntu 18.04 LTS – QT5 Applications on i.MX8QM board
Ubuntu 18.04 LTS – Gnome Calculator and GPU 3D Applications
Ubuntu 18.04LTS on iWave i.MX8 Quad Max / Quad Plus SOM & SBC
Ubuntu Bionic image with Wayland Compositor supports only Wayland graphical backend which is simpler than earlier X11 backend system and it includes below essential packages:
Linux Kernel Version 4.14.98
Ubuntu 18.04.03 LTS
Weston 5.0
QT 5.10
GPU driver 6.2.4.p4.0
Gstreamer 1.14.1
Bluez 5.48
GCC/G++ 7.3.0
Chromium Browser v71.0.3545.0
Supports Gnome-Calculator and Gnome-Calendar
iWave’s i.MX8 Single Board Computer and SMARC SOM
The following drivers are supported in the Ubuntu BSP with iWave i.MX8QM/QP SMARC SOM and SBC board
CPU and MCU – Dual Cortex® A72, Quad Cortex® A53 and Dual Cortex®-M4
Block/Storage devices – SD/eMMC, USB, SATA
Multimedia support – HDMI, MIPI-DSI, LVDS Display, GPU, VPU, Audio, Camera
Advantech, a global leader in the embedded computing market, is pleased to announce ROM-5720, a SMARC 2.0 module powered by the NXP ARM Cortex-A53 i.MX8M processor with excellent graphics performance and low power consumption. The ROM-5720 supports 4Kp60 resolution via HDMI 2.0 and 4Kp60 H.265 decoding with HDR. It features a variety of interfaces: USB3.0, PCIe, Dual Gigabit Ethernet, two MIPI-CSI, and a four-lane MIPI-DSI. ROM-5720 provides an ideal solution for a wide range of industrial applications such as infotainment, automation, HMI, and healthcare.
Excellent Graphics Performance for Machine Vision and Multimedia Applications
ROM-5720 adopts NXP i.MX8M SoC, which features up to four ARM Cortex-A53s and one additional general-purpose Cortex-M4 core processor for low-power processing. The ARM Cortex-A cores can be powered off while the Cortex-M4 subsystem performs low power, real-time system monitoring. The Vivante GPU supports the latest OpenGL ES, OpenCL , OpenVG, and Vulkan for advanced graphics and accelerated compute workloads such as the Deep Learning Inference. ROM-5720 supports display output with HDMI2.0 (4096 x 2160 @60Hz), 1×4 lanes MIPI-DSI for multiple display, and two MIPI-CSI camera input. It provides a high resolution display and meets camera requirements for different machine vision and multimedia applications.
High-Speed Connectivity Interfaces
To extend the flexibility of various applications, ROM-5720 offers a range of interfaces, such as dual USB3.0, dual Giga Ethernet, PCIe2.1, and four RS232. It provides efficient interfaces for extending peripheral devices like high-speed storage, camera, wireless modules, and it works with touch and legacy devices to empower self-service kiosks and interactive multimedia applications.
Advantech supports allied, industrial, and modular (AIM) frameworks for Linux to accelerate software development with flexible and responsive long-term support. AIM-Linux Services offers verified embedded OS platforms and industrial-focused apps and SDKs through which users can easily select the embedded software tools they need to focus on their vertical software development.
ROM-5720 Key Features
NXP i.MX8M with Quad/Dual Cortex A53 and Cortex-M4F up to 1.5GHz
Advantech ROM-5720 is available now! Please contact an Advantech sales office or authorized channel partners to learn more. For additional information on Advantech’s Arm computing products and services, visit risc.advantech.com now!
CircuitPython on an ARM Cortex M0 in 1 square inch! This “Just Add Solder” castellated module is perfect for incorporating into your own project. The CircuitBrains Basic board footprint is small enough to fit into narrow spaces and wearable projects.
Technical Specs
Dimensions: 25 x 25 x 3.5 millimeters / 1 x 1 x 0.15 inches
Atmel ATSAMD21E18 Microcontroller (32-bit ARM Cortex M0)
48 MHz
32 KB SRAM
256 KB Flash
4 MB QSPI Flash
Onboard 3.3V LDO Regulator
Power and Status LEDs
Breakouts for SPI and I2C
Breakouts for 4 Analog and 8 Digital Inputs/Outputs
CircuitBrains Deluxe
CircuitPython on an ARM Cortex M4 in almost 1 square inch! This “Just Add Solder” castellated module is perfect for incorporating into your own project. The CircuitBrains Deluxe board footprint is small enough to fit into narrow spaces and wearable projects.
Technical Specs
Dimensions: 29 x 29 x 3.5 millimeters / 1.15 x 1.15 x 0.15 inches
Atmel ATSAMD51J19A Microcontroller (32-bit ARM Cortex M4)
120 MHz
192 KB SRAM
512 KB Flash
8 MB QSPI Flash
Onboard 3.3V LDO Regulator
Power and Status LEDs
Breakouts for SPI and I2C
Breakouts for 14 Analog and 19 Digital Inputs/Outputs
Purchase
Coming soon. Follow the below links for manufacturing updates:
This is an easy to build but very capable and handy DIY solder paste dispenser built mostly from cheap Ebay components and modules by kevarek @ hackaday.io:
Already finished and nicely working solder paste dispenser. Powered with cheap ebay mini DC motor with gearbox (100RPM) and long M3 shaft secured by two axial bearings also from ebay. Body of both control box and dispenser is fully 3D printed. Accepts standard ebay 3ml luer lock syringes. Firmware supports dispensing speed configuration and also retraction to prevent leaks. Push button is available on the control box as well as on the handheld unit to be able to control the dispensing according to personal preferences.
Schematic is as simple as it gets. Power supply with basic protection, motor driver with voltage and current sensing and MCU to control the functionality.
MCU module with 3V3 regulator is bought from ebay, H-bridge and supply protection circuitry is hand soldered on piece of prototype PCB. Layout has not been created.
Mechanically the dispenser has two parts. Handheld dispenser and stationary control box. Handheld dispenser is 3D printed chassis with motor mounted inside and slot for 3cc syringe with luer lock.
Project files are available on the hackaday.io project’s page.
PoE FeatherWing is an Ethernet FeatherWing with 4W of PoE power with globally unique MAC.
Adafruit provides an Ethernet FeatherWing for its popular Feather ecosystem – a valuable option for IoT and automation projects. But it has its limitations. The Feather still needs to be powered separately, and no globally unique MAC address is provided for the user, making deployment hard.
What if we could fix these issues? What if there was a drop-in replacement that would not only provide Ethernet, but also power your Feather, and give you a globally unique MAC? And still be 100% compatible in size, connections and software support? Enter the PoE-FeatherWing!
Features
PoE: Isolated IEEE 802.3at Class 1, Mode A and Mode B Power over Ethernet, with 4 W of output power available.
Globally unique MAC address: A Microchip 24AA02E48 provides a real globally unique MAC address, allowing actual field deployment.
Works with existing software: A WIZnet W5500 Ethernet controller ensures full compatibility with existing software written for the Adafruit Ethernet FeatherWing.
Drop-in replacement: With board size and connections identical to the Adafruit Ethernet FeatherWing, it’s a true drop-in replacement.
Giant Board compatibility: A solder jumper allows for easy compatibility with the Giant Board Feather form-factor Linux SBC, without needing to add a fly wire for the IRQ (interrupt request signal).
The PoE FeatherWing is due to land on Crowd Supply soon; pricing has yet to be confirmed.
This smart device is able to monitor and display CO2, TVOC, PM, temperature, humidity and air pressure measurements. by Roman Novosad
Most of the modern applications focus on measuring outdoor air pollution. This is indeed very important and useful, however most of the time in person’s life is spent indoors. This is also an environment, where one is able to influence the climate using various air purifying instruments.
The negative change of indoor climate is often influenced by normal human behavior. For example levels of CO2 are increased in heavily occupied spaces with poor ventilation, levels of PM increase when cooking or smoking.
This points towards a greater need to monitor these air quality levels and be able to react to them in a timely manner.
The resistor (R), inductor (L), and capacitor (C) are the three elementary passive components of electronics. Their properties and behavior have already been detailed in the AC Resistance, AC Inductance, and AC Capacitance tutorials.
In this article, we will focus on the series association of these three components known as the series RLC circuit. First of all, a summary of the AC behavior of the three constitutive components is given in a presentation section along with a short introduction to the RLC circuit.
Series RLC circuit
In the second section, we discuss the electrical behavior of this circuit submitted to a DC voltage step and highlight why this particular response is important.
Next, we focus on the AC response of the RLC circuit by computing and plotting its transfer function in a third section.
Finally, we present two alternatives to the RLC circuit by switching the component between each other, and we see that the AC response gets completely different.
Presentation
A representation of the RLC circuit is given in Figure 1 below:
fig 1: Illustration of the series RLC circuit
The resistor is a purely resistive component that presents no phase-shift between the voltage and current across it. Its impedance (ZR) remains the same in DC and AC regime and is equal to R (in Ω).
The inductor is a purely reactive component with a phase-shift of +90° or +π/2 rad. Its impedance is given by ZL=jωL with ω being the angular pulsation of the voltage/current in an AC situation and L is the inductance (in H). In the DC regime, an inductor behaves as a short-circuit between two terminals and in the AC regime it becomes an open-circuit as the impedance increases with the frequency.
An inductor is often presented as a component that opposes the variations of current.
The capacitor is also a purely reactive component, but its phase-shift is -90° or -π/2 rad. Its impedance is given by ZC=-j/Cω with C being the capacitance (in F), it behaves therefore as an open-circuit in DC regime and as a short-circuit in AC regime when the frequency increases.
A capacitor is often presented as a component that opposes the variations of voltage.
In Figure 1, these three components are interconnected in series. The circuit is either supplied with a DC or AC source and the output is the voltage across the capacitor. The total impedance of the circuit is the sum of the independent impedances previously stated:
ZRLC=ZR+ZL+ZC=R+j(Lω-(1/Cω))
In the next section, we present the response of this circuit to a voltage step also known as the transient response.
Transient response
In this section, we will focus on the behavior of the circuit presented in Figure 1 when applying a Heaviside step H(t) to it:
fig 2: Illustration of the Heaviside function
The Heaviside step is characterized by being equal to 0 for t<0 and Vin for t>0. The transition between these two states is similar to an impulsion since the derivative tends to +∞ when t=0.
By doing a mesh analysis on the circuit, we can write that Vin=R×I+L×dI/dt+Vout. Moreover, we know that the current can be rewritten I=C×dVout/dt, which leads to the following second-order differential equation:
eq 1: Second-order differential equation of the series RLC circuit
The solution to such an equation is the sum of a permanent response (constant in time) and a transient response Vout,tr (variable in time). The permanent response is easy and obvious to find, the solution Vout=Vin is indeed a permanent solution of Equation 1.
The transient response is complex to determine and involves many steps that will not be detailed in this article. We will admit that its expression can take three different forms and depends on the value of Q=(1/R)√(L/C) called the quality factor of the circuit. Another important parameter is ω0=1/√(LC) which is the fundamental pulsation of the circuit.
When Q>1/2, the regime is said to be pseudo-periodic or to be an underdamped response, the transient response can be written with the form Vout,tr=Ae-αtcos(ωt+Φ). The constants A, α and Φ can be found by considering the initial conditions of the circuit (if the capacitor is charged or not …). The pulsation ω is called the pseudo-pulsation and depends on the fundamental pulsation ω0.
When Q<1/2, the regime is said to be aperiodic or to be an overdamped response, the transient response takes the form Vout,tr=e-αt(A1e-ωt+A2eωt).
Finally, the last case when Q=1/2, which corresponds to the critical regime or critically damped response. In this case, Vout,tr=(A+Bt)e-ω0t.
What is important to keep in mind is that these different solutions dictate how the voltage Vout behaves and tends to its permanent value Vin when a Heaviside step is applied to it:
fig 3: Curves of the different regimes for the transient response
We can comment on this figure by starting to say that each curve tends to 0 when the time increases. It makes sense because we know that Vout=Vin+Vout,tr and Vout(t→+∞)=Vin, therefore, Vout,tr→0.
However, the different possible transient responses do not tend to 0 with the same speed and behavior. The critical regime is the regime that tends the fastest to 0 meanwhile the aperiodic regime is the slowest. The pseudo-periodic regime presents oscillations which amplitude decreases exponentially.
For an unknown RLC circuit, identifying and matching the transient response with the best possible curve can give us the important properties of the circuit such as ω0and Q.
AC response
We consider in this section the same circuit presented in Figure 1 now supplied with an AC source. Using the property that in the complex notation, dX/dt=jωX with ω being the angular pulsation of the source, we can rewrite Equation 1 under the following form:
eq 2: Complex second-order differential equation of the series RLC circuit
We can then express the ratio Vout/Vin which is the transfer function T of the series RLC circuit:
eq 3: Transfer function of the series RLC circuit
Knowing that Q=(1/R)√(L/C), ω0=1/√(LC) and considering the parameter x=ω/ω0 called the reduced pulsation, we can rearrange Equation 3 to write the canonical form of the transfer function which simplifies and makes the expression more compact:
eq 4: Canonical form of the transfer function of the RLC circuit
It is interesting to plot the norm of the transfer function in order to obtain the gain of the circuit as a function of the parameter x. The values R=10 Ω and 20 Ω, L=0.2 H, and C=100 μF have been taken for this example:
fig 4: Gain of a series RLC circuit
We can note that the series RLC circuit presented in Figure 1 acts as a second-order low-pass filter in the AC regime since it decreases the output signal for the pulsations higher than ω0, which is commonly called the resonance frequency of the circuit.
Second-order filters have the property to slightly amplify the signal for the frequencies around ω0 and present a decrease of -40 dB/dec after the cutoff frequency, instead of only -20 dB/dec such as for first-order filters.
It is highlighted in Figure 4 that the value of Q (which depends on R) as an effect on the shape of the curve. The peak around the resonance frequency is indeed characterized by its bandwidth Δω=ω0/Q.
In this example, ω0=223 rad/s and Q=4.5 or 2.25, which gives a narrower bandwidth of Δω=50 rad/s for the orange curve and a wider one of 100 rad/s for the blue curve. We can, therefore, note that the quality factor dictates if the resonance is narrow (large Q) or wide (small Q).
Such as mentioned in the previous section, fitting the transfer function of an unknown circuit with the best possible curve enables us to have access to the properties of the circuit and therefore determine the value of its constitutional components.
RCL and CLR configurations
Other associations of the elementary component R, L, and C can provide different types of filters. We have seen previously that an RLC configuration is a second-order low-pass filter, but what if we switch some components between them?
Figures 5 and 6 present two new configurations which will be referred to as RCL and CLR circuits:
fig 5: Illustration of the RCL circuitfig 6: Illustration of the CLR circuit
Despite the small changes between these circuits and the original RLC circuit presented in Figure 1, the AC responses are very different.
It can indeed be shown that the transfer functions of these two circuits are given by Equations 4 and 5:
eq 5: RCL circuit transfer functioneq 6: CLR circuit transfer function
The nature of these new filters is revealed by plotting the norm of their transfer function with the same values: R=10 Ω and 20 Ω, L=0.2 H, and C=100 μF.
fig 7: Gain of series RCL and CLR circuits
The circuit RCL is a second-order high-pass filter since it attenuates the frequencies under ω0. The circuit CLR is a band-pass filter since it only amplifies frequencies in around ω0. Note that the same commentaries as in the previous section about the shape of the curve as a function of Q still apply for both these filters.
Conclusion
The series RLC circuit is simply an association in series of the three elementary components of electronics: resistor, inductor, and capacitor. The impedance of a resistor is a real number and the impedances of the inductor and capacitor are pure imaginary numbers, the total impedance of the circuit is a sum of these three impedances and is, therefore, a complex number.
The transient response of the circuit is first defined and presented in a second section. It consists of investigating the behavior of the circuit when supplied with a Heaviside voltage step. Through studying the possible solutions of the second-order differential equation associated with the circuit, three regimes appear to be possible:
The underdamped response where the signal slowly oscillates towards the permanent value Vin.
The overdamped response where the signal slowly increases towards the permanent value.
The critically damped response is the scenario where the signal increases the fastest towards the permanent value.
In a third section, the AC response of the circuit is presented. When supplied with an AC signal, the differential equation can be written in its complex form in order to find the transfer function of the circuit. Plotting the norm of this function reveals that the series RLC circuit behaves as a second-order low-pass filter.
In the last section, alternative configurations called RCL and CLR are investigated. This section shows that a second-order high-pass filter or a band-pass filter can be made from the same circuit by simply switching the components.