Secure Cellular Router Serves Industrial and Transportation Needs

Digi International has announced the Digi WR54, a rugged, secure, high-performance wireless router for complex mobile and industrial environments. With dual cellular interfaces, Digi WR54 provides immediate carrier failover for near-constant uptime and continuous connectivity, especially as vehicles move throughout a city or for locations with marginal cellular coverage. Together with a hardened milspec-certified design and built-in Digi TrustFence security framework, this LTE-Advanced router is designed specifically to meet the connectivity challenges inherent in multi-location, on-the-move conditions, from rail and public transit to trucking fleets and emergency vehicle applications.

LTE-Advanced technologies with carrier aggregation are pushing theoretical download speeds to 300 Mbps, and the next generation of cellular radios is capable of aggregating three or more channels for capabilities up to 600 Mbps. It’s expected that 5G deployments this year will push the demands for performance and edge computing even further. Digi WR54 provides an LTE-Advanced cellular module built on a platform that supports higher speeds to optimize bandwidth today while also being positioned for the future as network capabilities improve.

Multiple transit system use cases require rugged, reliable, high-speed connectivity solutions to carry mission-critical data and communications. Transit system integrators require connectivity for fleet tracking, logistics, engine and driver performance monitoring, fare collection and video monitoring; rail companies that are building in wayside data capabilities need constant visibility into complex systems; industrial corporations like utility companies need to monitor high-value assets.

The Digi WR54 architecture supports these performance requirements with not just the aforementioned LTE-Advanced cellular module, but four Gigabit Ethernet ports for wired systems and the latest 802.11 ac Wi-Fi which combine to support the needs of any user. Other key features include:

  • Dual-core 880 MHz MIPS processor: designed with this high-speed architecture, the Digi WR54 is future-built with a CPU capable of supporting higher network speeds and capabilities as infrastructure is updated to support them
  • SAE J1455, MILSTD-810G and IP-54 rated: tested and certified to withstand water, dust, heat, vibration and other environmental challenges suitable to transportation and many industrial applications
  • Optional dual-cellular radios for continuous connectivity between carriers: for users that cannot afford downtime, if the primary cellular carrier drops out, the Digi WR54 automatically and immediately switches over to the secondary carrier
  • Digi TrustFence: a device-security framework that simplifies the process of securing connected devices and adapts to new and evolving threats
  • Digi Remote Manager: with this Digi web-based management tool, users can simply manage their devices, receive alerts and monitor the health of their deployed devices

For users looking to add high-speed passenger Wi-Fi to mass transit systems, the recently launched Digi WR64 dual LTE-Advanced cellular and dual 802.11ac Wi-Fi router offers an all-in-one mobile communications solution for secure cellular connectivity between vehicles and a central operations center. It offers a flexible interface design with integrated Wi-Fi for client and access point connectivity along with USB, serial, a four-port wired Ethernet switch, GPS and Bluetooth in order to consolidate multiple transit or industrial applications into a single, consolidated router.

Digi International| www.digi.com

Nordic Semi’s BLE SoC Selected for Ultra Low Power IoT Module

Nordic Semiconductor has announced that Nanopower has selected Nordic’s nRF52832 Bluetooth Low Energy (Bluetooth LE) System-on-Chip (SoC) to provide the wireless connectivity for its nP-BLE52 module, designed for developers of IoT applications with highly restricted power budgets.

The nP-BLE52 module employs a proprietary power management IC—integrated alongside Nordic’s nRF52832 Wafer-Level Chip Scale Package (WL-CSP) SoC in a System-in-Package (SiP)—which enables it to cut power to the SoC, putting it in sleep mode, before waking it up a pre-set time and in the same state as before it was put to sleep. In doing so the SoC’s power consumption in sleep mode is reduced to 10 nA, making it well suited for IoT applications where battery life is critical by potentially increasing cell lifespan 10x.

In active mode, the nRF52832 SoC runs normally. The SoC has been engineered to minimize power consumption with features such as the 2.4GHz radio’s 5.5mA peak RX/TX currents and a fully-automatic power management system. Once the Nordic SoC has completed its tasks, it instructs the nP-BLE52 to put it to sleep and wake it up again at the pre-set time. The nP-BLE52 then stores the Nordics SoC’s state variables and waits until the nRF52832 SoC needs to be powered up again. On wake-up, the device uploads the previous state variables, allowing the Nordic SoC to be restored to the same operational state as before the power was cut. The SoC’s start-up is much more rapid than if it was activated from a non-powered mode.

The nP-BLE52 module also features a low power MCU which can be set to handle external sensors and actuators when the Nordic chip is switched off. In this state, the module still monitors sensors and buffer readings and can trigger wake-ups if these readings are above predetermined thresholds, while consuming less than 1 uA. The nP-BLE52 also integrates an embedded inertial measurement unit (IMU).

The module’s power management is controlled through a simple API, whereby the user can predetermine the duration of the Nordic SoC’s sleep mode, set the wake-up time and date parameters, and select pins for other on/off triggers.

The module offers IoT developers several advantages, either extending battery life and/or reducing the size of the battery required to power the application thereby reducing the end-product footprint. Longer battery life also reduces or eliminates battery swaps and enables the developer to better adjust for remaining useful battery life as the battery discharges. The module is suitable for any battery-powered device which is not required to be constantly active, for example asset tracking, remote monitoring, beacons, and some smart-home applications.

The nRF52832 WL-CSP SoC measures just 3.0 mm by 3.2mm while offering all the features of the conventionally-packaged chip. The nRF52832 is a powerful multiprotocol SoC ideally suited for Bluetooth LE and 2.4 GHz ultra low-power wireless applications. It combines an 64 MHz, 32-bit Arm Cortex M4F processor with a 2.4 GHz multiprotocol radio (supporting Bluetooth 5, ANT, and proprietary 2.4 GHz RF software) featuring -96dB RX sensitivity, with 512kB Flash memory and 64kB RAM.

The WL-CSP SoC is supplied with Nordic’s S132 SoftDevice, a Bluetooth 5-certifed RF software protocol stack for building advanced Bluetooth LE applications. The S132 SoftDevice features Central, Peripheral, Broadcaster, and Observer Bluetooth LE roles, supports up to twenty connections, and enables concurrent role operation. Nordic’s unique software architecture provides clear separation between the RF protocol software and the developer’s application code, easing product development.

Nordic Semiconductor | www.nordicsemi.com

IoT Wireless Sensor Nodes Target LPWAN Deployments

Advantech has released its WISE-4210 series of IoT wireless sensor products, including a wireless LPWAN-to-Ethernet AP and three wireless sensor nodes. The nodes include tthe WISE-4210-S231 internal temperature and humidity sensor (shown), WISE-4210-S251 sensor node with 6-channel digital input and a serial port and WISE-4210-S214 sensor node with 4-channel analog input and 4-channel digital input. The device-to-cloud total solution provided by this series of LPWAN products allows IT, OT, and cloud platform system developers to easily implement a private LPWAN, acquire field site data, and achieve seamless integration with both public cloud, such as Microsoft Azure and private enterprise clouds.

Based on proprietary LPWAN technology, the new WISE-4210 series products minimize frequency band interference, support a wider data transmission range, are compatible with lithium batteries, and enable cloud platform integration. By locking the sub-GHz frequency band, WISE-4210 series products significantly reduce susceptibility to interference for 2.4 GHz wireless communication technologies such as Wi-Fi, Bluetooth and Zigbee.

By supporting a network transmission distance of up to 5 km, the WISE-4210 series meets the requirements of large-scale interior environments such as data centers, factories and warehouses for collecting and applying a wide range of interior data. With LPWAN technology, only three 3.6 V lithium batteries are required to operate the WISE-4210 sensor nodes for up to five years, eliminating the need for additional wiring and frequent recharging. Additionally, the WISE-4210 series supports multiple transfer protocols, including MQTT, RESTful, Modbus/TCP and Modbus/RTU, for simple device-to-cloud connections.

The WISE-4210-S231 sensor node with built-in temperature and humidity sensor collects relevant data form factories, data centers or warehouse management without requiring the installation of additional sensors or gateways, making it ideal for indoor temperature and humidity control applications. Meanwhile, the WISE-4210-S251 sensor node, which provides 6-channel digital input and a single RS-485 port, and the WISE-4210-S214 sensor node, which provides four-channel analog input and 4-channel digital input, can be used to collect electricity meter, pressure gauge, thermometer, and power consumption data from factory facilities.

The three wireless nodes support direct data transmissions to SCADA and cloud platforms through a WISE-4210-AP, eliminating the need for a separate data conversion device. The WISE-4210-AP access point is capable of managing up to 64 nodes simultaneously, and thus can simplify overall infrastructure and save installation space.

Advantech | www.advantech.com

Wireless Charging

Electric Field of Dreams

The concept of wireless charging can be traced all the way back to Nikola Tesla. Here, Jeff examines the background and principles involved in charging devices today without wires, and takes a hands-on dive into the technology.

By Jeff Bachiochi

________________________________________________________

Nikola Tesla is the recognized inventor of the brushless AC induction motor, radio, fluorescent lighting, the capacitor discharge ignition system for automobile engines and more. His AC power (with Westinghouse) beat out Thomas Edison’s DC power in the bid for the electrification of America. DC transmission is limited to miles due to its relatively low voltage and its transmission line loses. Thanks to the advent of the transformer, AC can be manipulated allowing higher voltages and higher efficiency power transmission. Today’s research in superconducting cable may be challenging these concepts—but that’s a story for another time.

Tesla wanted to provide a method of broadcasting electrical energy without wires. The Wardenclyffe Tower Facility on Long Island Sound was to be used for broadcasting both wireless communications and the transmission of wireless power. Tesla even viewed his research on power transmission as more important than its use as a method for communications. Unfortunately, Nikola was never able to make his vision a reality.
We think of Guglielmo Marconi as being the father of radio for his development of Marconi’s law and a radio telegraph system. He was able to obtain a patent for the radio using some of Tesla’s own ideas. It’s interesting to note that after Tesla’s death in 1946, the U.S. Supreme Court invalidated the Marconi patent because the fundamental radio circuit had been anticipated by Tesla. Again, not the direction of this article.
It was likely that Nikola’s work in far-field power transmission had not been fruitful due to propagation losses (inverse square law). Even today’s work on beam-formed, far-field transmissions are marginally successful. Transformers are successful because they operate in the near field. The close proximity between the primary and secondary coil and a well-designed magnetic energy path result in low energy losses in transformers.

Modern Wireless Charging
Today’s wireless charging systems for our portable devices are based on transformer operation. However, the primary and secondary coils are not in physical contact yet still transfer energy Figure 1. Efforts to maximize the magnetic field’s coupling exist, but this less-than-ideal coupling reduces the efficiency of the transfer—50% to 70% efficient. There are basically two methodologies today: inductive (tight) coupling (near field) and resonant inductive (loose) coupling (mid field). The resonant circuit allows an equivalent power to be transferred at a slightly greater distance.

Figure 1
The device is considered near-field (closely coupled) when the distance between the coils is less than the coils diameter. The mid-field device’s distance exceeds the coils diameter and relies on resonance to improve its power transfer.

Wireless efforts are in total flux with at least three organizations jockeying for position: The Wireless Power Consortium (WPC, induction), the Alliance for Wireless Power (A4WP, resonant) and Power Matters Alliance (PMA, induction). Interestingly, after WPC announced its plans to widen their specs to include resonant technologies, A4WP and PMA merged to become the AirFuel Alliance and now cover both technologies as well.

Beyond induction type, the biggest differences between the technologies is in control communication. Control of the charging process requires communications between transmitters and receivers. Induction technology uses in-band modulation of the RF signal to send and receive communications. Resonant induction technology uses Bluetooth for out-of-band communications. This makes the transmitter/receiver pair simpler but adds the complexity of Bluetooth. Since many receiving devices already have Bluetooth, this may be moot.

The Qi Standard
The WPC has coined the term Qi for their standard. If you search the web for wireless charging, this term pops up all over the place. This is not to say the AirFuel’s standard isn’t available—it seems to be a difference in promotional strategies. AirFuel has invested in getting their receivers into devices and their transmitters installed in public places. And while Qi receivers are also going into devices, their transmitters seem to be aimed at the individual. That means easy access to both Qi transmitters and receivers.
You can get the V1.2.2 specifications for the Qi standard from the WPC website. The current version (1.2.3) is available only to members now but should be public shortly. The two documents I received were “Reference Designs” and “Interface Definitions” for Power Class 0 specifications.

Power Class 0 aims to deliver up to 5 W of energy wirelessly via magnetic induction. This is accomplished by applying a fixed RF signal—generally in the 140 kHz range—into an inductive load (transformer primary). This is much like providing motor control using a half or full bridge, with the (transmitting) coil as the load instead of a motor.
Referring back to Figure 1, a receiver uses a similar coil (the transformer secondary). This coil supplies rectification circuitry with the voltage/current needed to power the receiver. The receiver can vary its load, which modulates the burden on the transmitting coil. Back at the transmitter, a change in the primary’s current can indicate when the secondary’s load is in range. Initially the transmitters remain relatively inactive, except for a periodic “ping” to look for a receiver. A normal ping will occur every
500 ms and last about 70 ms (Photo 1). Once in range the receiver gets secondary current and can self-power. During the last 50 ms of a ping, a receiver has a chance to communicate by modulating its load at 2 kHz rate (Photo 2). There are presently 16 messages it can choose to send.

Photo 1
This oscilloscope screenshot shows the “ping” transmissions of a wireless transmitter with no receiver in range.

Photo 2
Here we see a receiver sending a packet by modulating its load during the transmitter’s RF transmission.

Each message has four parts: a preamble, header, message and checksum. The preamble consists of from 11 to 25 “1” wake-up bits. The header is a 1-byte command value. The message length is fixed for each command, presently 1 to 8 bytes. The checksum is a 1-byte sum of the header and message bytes. All bytes in the header, message and checksum have an 11-bit asynchronous format consisting of a start bit (0), data bits (for example Command, LSB first), odd parity bit (OP) and stop bit (1). Each bit is sent using bi-phase encoding. Each bit begins with a state change in sync with its 2 kHz clock. The value of a bit is “0” when its logic states does not change during a 2 kHz clock period. If the state does change within that period, then the bit is a “1”.

The receiver has control over the transmitter. It initiates communication to send information and request power transfer. Back in Photo 2 you can see a Control Error Packet with a Header=0x03 and data=0x00. The signed value of the data indicates any difference between the requested and received current level.

While the receiver is in charge (ha!), the transmitter can acknowledge requests with 1 of 3 responses: ACK (accept), NAK (deny), or ND (invalid). Responses have no packet per se, but are merely a Frequency-shift keying (FSK) modulated pattern of 0s, 1s or alternating 0s and 1s. The receiver can request the depth of the FSK modulation from a list of choices between +/- 30 to 282 ns. The depth is defined as the difference in ns between the 1/Fop (operating frequency) and 1/Fmod (modulation frequency). The format is again bi-phase encoding in sync with the RF frequency. All bits begin with a change in modulation frequency. A “1” bit is indicated by a change in frequency after 256 cycles, while a ‘”0” bit has no change until the beginning of the next bit time. Responses are therefore easy for a receiver to demodulate.

So, communication is AM back-scatter from the receiver and FM on the base RF from the transmitter. The present specification defines three packets that can be sent by a transmitter in addition to the ACK, NAK and ND. These are informational and are formatted like the receiver packets, less the preamble.

System Control
From the transmitters point of view, it has 4 basic states: ping, ID, power transfer and selection. The transmitter is idle while in the ping state. Without some communication from a receiver, the transmitter will never do anything but ping. Once communication begins the receiver attempts to identify itself and become configured, at which point the transmitter can start power transfer. The transmitter will continue monitoring its feedback and change states when necessary. For instance, if communication is lost, it must cancel the power transfer state and begin to ping. The ability to detect foreign objects (FOD) is required for any system that can exceed 5W of power transfer. This parameter adds an additional 3 states to the basic 4 states: negotiation, calibration and renegotiation. When using FOD the negotiation state is required to complete identification, configuration and calibration. Calibration allows the transmitter to fine tune its ability to FOD. During the power transfer state, the receiver may wish to adjust its configuration. As long as no requests violate operational parameters, the power transfer state can continue. Otherwise the selection state will redirect further action. You can see how this works in the state diagram in Figure 2.

Figure 2
This is a general state diagram of the Qi standard for wireless chargers. Note two potential paths based whether or not foreign object detection is supported (required for greater than 5 W).

From the receiver’s point of view, it could be in an unpowered (dead) state prior to entering the transmitter’s field. Once within range, the short ping from a transmitter is sufficient to charge up its capacitive supply and begin its application programming. Its first order of business is to look for a legal ping, so it can properly time its first request 40ms after the beginning of a ping. The first packet is a signal strength measurement, some indication of transmitted energy. This is sufficient for the transmitter to enter the identification and configuration state by extending its RF timing and look for additional packets from the receiver. The receiver must now identify itself—version, manufacturer and whether or not it accepts the FOD extensions. A configuration packet will transfer its requirements as well as the optional packets it should expect. The transmitter digests all this data and will determined, based on the receiver’s ability to accept FOD extensions, whether it will proceed directly to the power transfer state or enter the negotiation state.

Packets must have a minimum of 7 ms silent period between each. The values sent in the configuration packet denote an official power contract between the transmitter and receiver. When the receiver doesn’t accept FOD extensions, it is this contract that the transmitter will abide by once it enters the power transfer state. If FOD extensions are enabled, it enters the negotiation state in an attempt to change the contract and provide higher power. The transmitter’s response lets the receiver know when a request to change a parameter is acceptable. This way both receiver and transmitter agree on the power contract it will use when negotiations are closed.

Once negotiations have ended, the calibration state is entered. The calibration consists of multiple packets containing received power values measured by the receiver while it enables and disables its load (maximum and minimum power requirements). This provides the transmitter with some real use values so it can better determine FOD.
During the power transfer (PT) state, the receiver must send a control error packet every 250 ms that the transmitter uses to determine its operating (PID) parameters. Meanwhile, received power packets are sent every 1,500 ms. Without this feedback, the transmitter will drop out of the PT state. Other packets can affect the PT state as well—most notably an end power packet. This may be due to a full charge or other safety issue and the transmitter drops out of the PT state. At this point a receiver can cease communication and while the transmitter will begin pinging, the receiver can rest indefinitely.

Sense, Configure, Charge
I’ve found that the Qi receivers with micro USB connectors make it easy to add wireless charging to your phone or tablet. One of these fits inside my Motorola phone with only the smallest bump of the connector on the outside. My Amazon Fire is not so lucky. It had to stay on the outside (Photo 3).

Photo 3
Shown on the left, the Amazon Fire required me to add the Qi receiver to the outside. It’s covered with a very large band-aid. On the right, my Motorola phone had room inside. The only clue is the receiver’s minimally obtrusive micro USB connector.

Adafruit has a module available that has no connector and is not enclosed in a skin (Photo 4). You can see in that photo that a receiver requires very few external components. This one uses a Texas Instruments bq51013B, which is less than $4. One advantage to choosing this device is the non-BGA version which is appealing to the DIYer that wants to hand solder the device onto a PCB.

Photo 4
You can see how few components are required on the Adafruit Qi wireless receiver shown here on a wireless transmitter. The voltmeter shows a voltage output of 4.98 V.

I suggest that you use high strand, flexible wires when making connections to this because a stiff wire can cause undue stress on flexible circuitry. I want to use this wireless charge receiver to keep some of my robots charged. To do this, the robot has to ride over the top of a transmitter. The receiver would then recharge the on-board battery or batteries. I’ve chosen to use Li-ion batteries because they have a high power-to-weight ratio. They also have a relatively flat discharge curve. Unfortunately, a single cell 3.7-V Li-ion battery is not sufficient to power most motors. Therefore, multiple cells must be used.

When multiple cells are in series the charging becomes an issue because the cells should be charged using a balanced charger to prevent charge imbalance. Charging cells in series as a group cannot prevent the over/under charging of individual cells. This means one of two approaches: Use a single cell and use a boost power converter to obtain your necessary voltage, or use a more complicated multi-cell, balanced charger with a boost converter between the wireless receiver and the charger’s input.
Upon contemplating the pros and cons of each method, I’ve decided to use a modular approach by treating each battery as a separate entity. The simplest charging IC I could find was STMicroelectronics’ STC4054. This is a TSOT23-5L (5-pin) device that requires only one external component to set the charging rate. This is important because some chargers will allow very high currents and I will be sharing the current for all chargers via one wireless receiver. While these can handle 1 A, if I want to say, charge four Li-ion batteries in series I need to limit each charging circuit to 250 mA (250 X 4 = 1,000) or I run the risk of the wireless receiver becoming overloaded and everything will shut down.

The STC4054 has a charging voltage of 4.2 V using the maximum of whatever current you set by the resistor you choose from the PROG pin to ground using the following formula:

rearranging we get…

A minimum VCC of 4.25 V is sufficient to sustain a complete charge cycle. Here is a breakdown of the whole charge cycle: If the battery voltage is below 2.9 V it will be trickle charged at 1/10 of IBAT. Once it reaches 2.9 V it enters the constant current mode charging at IBAT. Once it reaches 4.2 V it switches to constant voltage mode to prevent over charging. The cycle ends when the current drops to less than 1/10 of IBAT. Should the battery voltage fall below 4.05 V, a charging cycle will begin to maintain the battery capacity to a value higher than 80%.

The STC4054 is thermally protected by reducing the charging current should the temperature approach 120°C. The package leads are the main heat conductors from the die, so sufficient copper areas on the PCB will help with heat radiation. The device will max at 800 mA, but is spec’d to handle 500 mA at 50°C. You can expect stability without additional compensation unless you have long leads to the battery. A 1 µF to 4.7 µF capacitor can be added to the BAT connection if necessary.

The CHRG pin is an open-collector output which can be monitored to indicate when the IC is in the charging state. It will pull down an LED if you wish a visual status indicator. This IC will cost you about $1.50. With no voltage applied to the IC, it will go into a power down mode with a drain of only 17 µA on the battery.

Now this circuit takes care of charging a single battery, and we might have up to four in series. It’s the series part that is the problem because only the first can have a reference to ground. Since the wireless receiver is designed to produce a 5 V output, this is easily connected to the first charging circuit. We could try and get fancy with a boost converter to get a 20 V output to feed the four chargers with their inputs in series, but this has all kinds of bad karma associated with it. Fortunately, there is a rather inexpensive solution: Use isolated DC-DC converter modules. All converter inputs are in parallel on the wireless chargers output. Each of the converters’ outputs can be tied to a separate charging circuit. Since each of the converters’ outputs are isolated from its inputs, there is no reference to ground—the minus output of the wireless receiver). That means they can then be used to charge batteries which are connected in series.

The circuit given in Figure 3 shows four changing circuits—each (potentially) using its own isolated 5 VDC to 5 VDC converter. These are available in 1 W to 3 W SIP-style packages and cost from $3 to $10 each. Modules with high current (greater than 3W) are available, but the package style changes to DIP. Their inputs are in parallel with a connector meant to go to the wireless charging receiver. There are a lot of jumpers used to select how the outputs of each charging circuit are to be connected to output connectors. Each charger can charge one Li-ion battery using a standard two-pin 1S1P (one series cell, one parallel cell) connector. Or you can jumper them in series, which uses the standard connectors for 2S1P, 3S1P and 4S1P (series cells).

Figure 3
This schematic shows four Li-ion cell charging circuits using the STC4054. The input to each IC can come from an optional isolated source when using a DC-DC converter from RECOM. If each of the charging circuits are isolated, they can be applied to separate Li-ion cells in series.

You’ll note that multi cell Li-ion battery packs usually come with two connectors—one for use and one for charging. The charging connector contains a wire to each battery junction to allow cell-balanced charging (Photo 5). Battery packs that feature balanced charging usually contain the JST HX connector for charging. The power contacts are another story. They may be JST HSNG style, Dean’s connector or other specialty types.

Photo 5
There seems to be some standardization on balanced Li-ion cell chargers. They require a common plus 1 wire for each cell so each cell can be monitored and charged independently. This means any battery pack with more than one cell requires separate connectors for charging and discharging.

Small Bots ‘n Bats
You’ll find plenty of the small robot bases using AA batteries with a UNO or some other micro platform as its controller. There is nothing wrong with these inexpensive platforms for educational purposes. With a fresh set of batteries, you will usually have predictable behavior. In rather short order however, things will begin to go loony. The motor load will begin to affect the controller as the battery voltage dips. Even at 6 V, with a low drop out regulator, the controller operation and any sensors will quickly become unpredictable. This can be truly a frustrating time for the newbie, as one searches their code for a logic error that might produce the inappropriate action observed, when actually there may be nothing wrong!

You can save a lot of heartache if you just add an extra battery (or two) to raise the voltage to 7.5 V or even better 9 V. I’ve seen kids quickly lose interest or give up entirely simply because they don’t understand what’s happening. I’ve found a better solution is to replace the AAs with a couple of Li-ion 18650 type 3.7 V cells. The 18650 looks like an over-sized AA battery and has battery holders that are similar (Photo 6). You can expect about 2,000 mA-hours from AA cells. The 18650 Li-ion cells pack about three times the energy and they can be popped out and recharged in a few hours. Li-ion flat packs can also be used here, but they are not as “universal” as the 18650 single cells.

Photo 6
Replacing four AA cells with two 18650 Li-ion cells can save a lot of head scratching when unexpected behavior is due to battery droop. The AA cells (4 x 1.5 V) does not leave much headroom when a 5 V regulator is used. Not only is the discharge curve relatively flat for Li-ion cells (2 x 3.7 V) preventing drops in regulation, but the 18650 packs 3 times the energy.

It is a good idea to remove batteries from any equipment that will not be used for extended periods of time. Many devices today—like the ones with auto off functions—have parasitic circuits that continue to draw minuscule currents even when “off”. These will continue to draw down your batteries until they are unusable. Even though Li-ion cells have a protective circuit that prevents them from being discharged below a safe level—approximately 2.75 V/cell—this internal circuitry is parasitic and acts as a tiny load. While self-discharge is only a few percent per month, once the cell voltage drops below a critical voltage this circuitry may not allow it to be recharged. So always store a rechargeable in a “charged” state.

Wireless Charging today
Wireless charging is only in its infancy. Today’s phone chargers are typically less than 5 W. But there is work being done on higher rated equipment. It is proper that these low power devices have such safeguards built-in to prevent unwanted catastrophes. We know from the not too distant past that, along with higher power density materials, comes the potential for calamity unless the proper safeguards are in place. Public education can limit the misuse and/or abuse of lithium technology, just as it has for the safe handling and use of gasoline.

In order for the electric vehicle to become useful, we will need to replenish its range-defining battery charge in fairly short order. This requires extreme infrastructure changes. You can tell by the size of the connectors and cable required for this process that this is high power. The holy grail is for this to happen wirelessly and automatically. From a simple pad embedded in ground where you park your vehicle, to a highway infrastructure that transfers power to your vehicle while you drive. Wireless power transfer is here to stay. Nikola Tesla must be at peace knowing that his work is beginning to bear fruit.

Additional materials from the author are available at:www.circuitcellar.com/article-materials

RESOURCES

Adafruit | www.adafruit.com
RECOM | www.recom-power.com
STMicrolectronics | www.st.com
Texas Instruments | www.ti.com

See the article in the May 334 issue of Circuit Cellar

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Module Meets Needs of Simple Bluetooth Low Energy Systems

Laird has announced its new Bluetooth 5 module series, designed to simplify the process of bringing wireless designs to market. The BL651 Series is the latest addition to Laird’s Nordic Semiconductor family of Bluetooth 5 offerings. Building on the success of the BL652 and BL654 series, the BL651 is a cost-effective solution for simple Bluetooth Low Energy (BLE) applications that provides all the capabilities of the Nordic nRF52810 silicon in a small, fully certified module.

The BL651 leverages the benefits of Bluetooth 5 features, including higher data throughput and increased broadcasting capacity, in a tiny footprint. According to the company, the BL651 has been designed to allow a seamless hardware upgrade path to the more fully featured BL652 series if additional flash and RAM requirements are identified in the customer development process.

The BL651 series delivers the capabilities of the Nordic nRF52810 silicon in a small, fully certified module with simple soldering castellation for easy prototyping and mass production manufacturing. Designers can use the Nordic SDK and SoftDevice or Zephyr RTOS to build their BLE application. In addition, the BL651 series is 100% PCB footprint drop in compatible with the BL652 Series of modules, allowing flexibility to upscale designs if more flash/RAM or further feature sets are required during the design process.

In large factories Bluetooth sensor networks can easily span an entire campus and gather sensor data that can provide deep insights needed to maintain efficiency, productivity and security. The BL651 Series helps make these types of sensor networks easy to build, scale, and maintain.

Laird Connectivity | www.lairdtech.com

Connected Padlock Uses U-Blox BLE and Cellular Modules

U‑blox has announced their collaboration with India‑based Play Inc. on a connected GPS padlock for industrial applications. The lock, which doubles as a location tracker, features a U‑blox M8 GNSS receiver, MAX‑M8Q, and uses the u‑blox CellLocate service to extend positioning to indoor locations. U‑blox Bluetooth low energy with NINA‑B112, and 2G, 3G and 4G U‑blox cellular communication modules, including some that are ATEX certified, enable communication between users and the lock.
According to the company, In many industrial settings, locks are an unwelcome bottleneck. They typically require the physical presence of a person with a key to open them, they need to be checked periodically for signs of tampering, and when they are forced open, owners typically find out too late. Play Inc’s i‑Lock combines physical toughness and wireless technology to address these challenges. Offering a variety of access methods, including physical keys and keyless approaches using remote GPRS and SMS passwords as well as Bluetooth low energy or cloud‑based communication via mobile device apps, the i‑Lock lets plant managers or other customers flexibly grant authorization to access the goods that are under lock. And in the event that the padlock is forcefully opened, they are immediately alerted via a server or, optionally, SMS texting.

In addition to securing mobile and stationary goods, the lock’s GNSS receiver lets users track goods in transit. The i‑Lock supports a variety of tracking modes to optimize power consumption for increased autonomy. Location‑awareness further enables geofence restricted applications, in which the i‑Lock can only be open if it is within predefined geographical bounds—for example a petroleum filling station.

The security lock was designed to endure both physical attempts of tampering and cyberattacks. Its fiberglass reinforced enclosure withstands temperatures from -20 to +80 degrees C. The lock features Super Admin, Admin, and User access levels, 128-bit AES encryption, user‑configurable passwords, and a secure protocol to ensure data‑transmission accuracy.

The i‑Lock will be presented at The IoT Solutions Congress Barcelona on October 16‑18, 2018.

U-blox | www.u-blox.com

Enter to Win a Wireless Pen-Sized Oscilloscope!

IKALOGIC is giving away an IkaScope! (retail value $379)

The IkaScope WS200 is a pen-shaped battery-powered wireless oscilloscope that streams captured signals to almost any Wi-Fi-connected screen.

GO HERE TO ENTER TO WIN!

The IkaScope WS200 offers a 30 MHz bandwidth with its 200 Msamples/s sampling rate and maximum input of +/-40 Vpp. It provides galvanically-isolated measurements even when a USB connection is charging the internal battery. The IkaScope WS200 will work on desktop computers (Windows, Mac and Linux) as well as on mobile devices like tablets or smartphones. The free application software can be downloaded for whichever platform is needed.
The IkaScope WS200 has no power switch. It detects pressure on the probe tip and turns on automatically. Patented ProbeClick technology saves battery life: all power-consuming circuitry is only turned on when the probe tip is pressed, and the IkaScope WS200 automatically shuts down completely after a short period of non-use. The internal 450 mAh battery lasts about one week with daily regular use before recharging is necessary. An isolated USB connection allows for recharging the internal battery: two LEDs in the unit indicate battery charge and Wi-Fi status.

Clicking the Autoset button on the IkaScope software automatically adjusts gain and time-base to quickly view the signal optimally. The IkaScope WS200 also knows when to measure and when to hold the signal display without the need for a Run/Stop button. The IkaScope’s innovative Automatic History feature saves a capture of the signal when releasing pressure on the ProbeClick tip. The History Database is divided into Current Session and Favorites, where signal captures are permanently saved, even after the application is closed. Previously measured signals can quickly be recalled.

Most desktop oscilloscopes have a static reference grid with a fixed number of divisions, but the IkaScope allows pinch and zoom on touch screens (or zoom in/out with a mouse wheel), stretching the grid and allowing an operator to move and zoom through a signal capture for detailed review. The associated software even has a share button on the screen: simply click on it to share screenshot measurements.

IKALOGIC | www,ikalogic.com

 

IoT Platform Release Provides Improved Wireless Capabilities

Ayla Networks has announced new capabilities to its IoT platform that will further simplify the ability to gain business value from IoT. This new Ayla IoT platform release overcomes restrictions on choosing wireless modules to connect to the Ayla IoT cloud and streamlines the creation of enterprise applications that use IoT device data.

A new Ayla portable software agent significantly cuts the time needed to get to market with IoT initiatives, by allowing manufacturers to select essentially any cellular or Wi-Fi module and have it connect easily to the Ayla IoT cloud. For makers of IoT solutions and service providers, the Ayla IoT platform has added new application enablement capabilities that make it faster and easier to build both mobile and web-based enterprise applications that take advantage of IoT data.
To connect to an IoT cloud, devices use an embedded cellular or Wi-Fi module, comprising both a hardware chip and a software agent, that provides wireless cloud connectivity. Until now, IoT software agents had to be built and certified to work with a specific chip and module type, an expensive process that could take a year or more and involve significant certification overhead.

The new Ayla portable agent circumvents this problem by enabling connectivity to the Ayla IoT cloud from any cellular or Wi-Fi module—without the lengthy process of certifying a different software agent for each chip or module variation, and without having to generate source code to port the agent to a chosen module. As a result, IoT solution providers that want to connect to the Ayla IoT cloud are no longer restricted to a list of certified cellular or Wi-Fi modules; instead, they can take a bring-your-own (BYO) approach to IoT modules.

The Ayla portable agent includes source code, reference implementation, a porting guide, and a test suite for both cellular and Wi-Fi solutions. In addition, Ayla Networks can recommend development partners able to perform porting work for enterprises that lack in-house IoT firmware development expertise.

The Ayla Web Software Development Kit (SDK) reduces development cycles for applications that leverage IoT device data in conjunction with an enterprise’s other cloud or data integrations. A new product, the Ayla Web SDK makes it easy for developers to create business applications on top of the Ayla IoT platform. It provides pre-packaged functionality for user management, device monitoring, session management and rule-based access control (RBAC) management.

Ayla Networks | www.aylanetworks.com.

LDO Regulators Target LoRa-Based IoT Systems

Semtech has added a new product to its nanoSmart platform of low power, Low Dropout (LDO) regulators that targets applications for IoT sensors including Semtech’s LoRa devices and wireless radio frequency technology (LoRa Technology).

A consistent voltage output with low noise (100μVRMS) is necessary for low-power radio devices, such as LoRa-based sensors, to function without noise interference with radio information transmission. The new nanoSmart SC573 device’s low quiescent current (50μA) enables energy savings in everyday products by extending operating life for battery-powered IoT sensors up to 10 years. The IC is ideal for developers designing solutions for industrial and consumer applications including smart metering and smart building.

Semtech’s nanoSmart ultra-low power technology enables energy savings in everyday products. The nanoSmart LDO products support multiple energy accumulation technologies including thermal, RF and indoor and outdoor solar. The platform implements advanced system power management and has a real-time clock making it ideal for remote sensing and control applications.

Features:

  • Shutdown current — 100 nA
  • Output noise — 100 μVRMS /V
  • Quiescent supply current — 50 μA
  • Input voltage range — 2.3 V to 5V
  • Single 300 mA (maximum) output
  • Internal 100 Ω output discharge
  • Dropout at 300 mA load — 180 mV

The new nanoSmart LDO is currently available in 2 voltages (3.3V and 1.8V) and is priced at $0.130 in volumes of 10,000 units.

Semtech | www.semtech.com

Bluetooth SIG Appoints New Associate Member Directors

The Bluetooth Special Interest Group (SIG) announced that Peter Liu from Bose and Ron Wong from Cypress Semiconductor will be joining the board of directors of the Bluetooth SIG as Associate Member Directors. The Bluetooth SIG Board of Directors is responsible for the governance of the organization and plays a vital role in driving the expansion of Bluetooth technology to address the needs of a growing number of consumer and commercial markets. Both will serve a two-year term starting in July 2018.

Peter Liu (left) is an Architect of Wearable Systems at Bose, leading programs and creating technology platforms for hearables. Previously, he led the Advanced Electronic Systems group in Bose Consumer Headphones to deliver enabling technologies and architectures for the wireless and noise-cancelling headphones enjoyed today by audio enthusiasts worldwide. Peter delights in bringing new experiences to life by drawing upon his expertise and network cultivated over a career spanning semiconductors and end-products in infrastructure, cellular and consumer electronics industries.

Ron Wong (right) is Director, Product Marketing in the Microcontroller & Connectivity Division of Cypress Semiconductor and manages connectivity software solutions that help companies bring innovative, low-power connected products to market. He is responsible for defining and driving Cypress’ Internet of Things (IoT) product portfolio, including Bluetooth software and Wireless Connectivity for Embedded Devices (WICED) development kits. A veteran of wireless technology, Ron has more than 25 years of experience in wireless communications including 18 years in Bluetooth technology.

With these new appointments, the Bluetooth SIG board now consists of individuals from the following member companies; Apple, Bose, Cypress Semiconductor, Ericsson, Google, Intel, Lenovo, Microsoft, Nokia, Signify and Toshiba.

Bluetooth SIG | www.bluetooth.com

Cypress Semiconductor | www.cypress,com

Wireless MCUs are Bluetooth Mesh Certified

Cypress Semiconductor has announced its single-chip solutions for the Internet of Things (IoT) are Bluetooth mesh connectivity certified by the Bluetooth Special Interest Group (SIG) to a consumer product. LEDVANCE announced the market’s first Bluetooth mesh qualified LED lighting products, which leverage Cypress’ Bluetooth mesh technology. Three Cypress wireless combo chips and the latest version of its Wireless Internet Connectivity for Embedded Devices (WICED) software development kit (SDK) support Bluetooth connectivity with mesh networking capability. Cypress’ solutions enable a low-cost, low-power mesh network of devices that can communicate with each other–and with smartphones, tablets and voice-controlled home assistants–via simple, secure and ubiquitous Bluetooth connectivity.

Previously, users needed to be in the immediate vicinity of a Bluetooth device to control it without an added hub. With Bluetooth mesh networking technology, the devices within the network can communicate with each other to easily provide coverage throughout even the largest homes, allowing users to conveniently control all of the devices via apps on their smartphones and tablets.

Market research firm ABI Research forecasts there will be more than 57 million Bluetooth smart lightbulbs by 2021. Cypress’ CYW20719, CYW20706, and CYW20735 Bluetooth and Bluetooth Low Energy (BLE) combo solutions and CYW43569 and CYW43570 Wi-Fi and Bluetooth combo solutions offer fully compliant Bluetooth mesh. Cypress also offers Bluetooth mesh certified modules and an evaluation kit. The solutions share a common, widely-deployed Bluetooth stack and are supported in version 6.1 of Cypress’ all-inclusive WICED SDK, which streamlines the integration of wireless technologies for developers of smart home lighting and appliances, as well as healthcare applications.

Cypress Semiconductor | www.cypress.com

BLE ICs Boast -105 dBm Sensitivity

Toshiba Electronic Devices & Storage has added two new devices to its lineup of ICs that are compliant with the Bluetooth low energy standard. The new TC35680FSG (featuring built-in flash memory) and TC35681FSG are well-suited to applications requiring long-range communication, including beacon tags, IoT devices and industrial equipment. Sample shipments will begin later this month.

The new communication ICs support the full spectrum of data rates required for the high-speed features—2M PHY and Coded PHY (500 kbps and 125 kbps)—found in the Bluetooth 5.0 standard. The new devices also deliver an industry-leading receiver sensitivity level of -105 dBm (at125k bps ) and a built-in high efficiency power amplifier in the transmission block that provides up to +8 dBm transmission power.

Bluetooth technology continues to evolve to meet wireless connectivity needs, and recent enhancements to the standard have been designed to increase Bluetooth’s functionality with the IoT. By adding Bluetooth 5.0-compliant ICs to its extensive lineup, Toshiba helps companies integrate Bluetooth low energy products into IoT devices and addresses the growing demand for high-throughput, long-range communications.

Based on an ARM Cortex-M0 processor, the new ICs incorporate a 256 KB Mask ROM to support the Bluetooth baseband process, and 144 KB of RAM for processing Bluetooth baseband, stack and data. Toshiba’s TC35680FSG and TC35681FSG also feature 18-port GPIOs as interfaces, which can be set to 2 channels each for SPIs, I2C, and UART. This allows for the structuring of systems that connect to various peripheral devices. These GPIOs can be set for a wakeup function, 4-channel PWM, 5-channel AD converter interfaces, an external amplifier control interface for long-range communication and more.

The TC35680FSG includes 128 KB of flash memory for storing user programs and various data in stand-alone operations, making it well-suited to a wide range of applications and removing the need for external non-volatile memory. This also lowers the part count, which reduces both the cost and mounting area.

The TC35681FSG, which does not include a built-in flash memory, operates in conjunction with an external non-volatile memory or host processor. A wide operating range of -40° to +125°C makes it suitable for applications exposed to high temperatures.

Toshiba Electronic Devices & Storage | www.toshiba.semicon-storage.com

Op Amp Features Ultra-High Precision

Texas Instruments (TI) has introduced an op amp that combines ultra-high precision with low supply current. The LPV821 zero-drift, nanopower op amp enables engineers to attain the highest DC precision, while consuming 60% less power than competitive zero-drift devices, according to TI. The LPV821 is designed for use in precision applications such as wireless sensing nodes, home and factory automation equipment, and portable electronics.

LS-First-Page

The LPV821 is a single-channel, nanopower, zero-drift operational amplifier for “Always ON” sensing applications in wireless and wired equipment where low input offset is required. With the combination of low initial offset, low offset drift, and 8 kHz of bandwidth from 650 nA of quiescent current, the LPV821 is the industry’s lowest power zero-drift amplifier that can be used for end equipment that monitor current consumption, temperature, gas, or strain gauges.

The LPV821 zero-drift op amp uses a proprietary auto-calibration technique to simultaneously provide low offset voltage (10 μV, maximum) and minimal drift over time and temperature. In addition to having low offset and ultra-low quiescent current, the LPV821 amplifier has pico-amp bias currents which reduce errors commonly introduced in applications monitoring sensors with high output impedance and amplifier configurations with megaohm feedback resistors.

Engineers can pair the LPV821 op amp with the TLV3691 nanopower comparator or ADS7142 nanopower analog-to-digital converter (ADC) to program a threshold that will automatically wake up a microcontroller (MCU) such as the CC1310 SimpleLink Sub-1 GHz MCU, further reducing system power consumption.

Designers can download the TINA-TI SPICE model to simulate their designs and predict circuit behavior when using the LPV821 op amp. Engineers can also jump-start gas-sensing system designs using the LPV821 op amp with the Always-On Low-Power Gas Sensing with 10+ Year Coin Cell Battery Life Reference Design and Micropower Electrochemical Gas Sensor Amplifier Reference Design.

Pre-production samples of the LPV821 op amp are now available through the TI store and authorized distributors in a 5-pin small-outline transistor (SOT-23) package. Pricing starts at $0.80 in 1,000-unit quantities.

Texas Instruments | www.ti.com

Flexible Printed Batteries Target IoT Devices

Semtech and Imprint Energy have announced a collaboration to accelerate the widespread deployment of IoT devices. Imprint Energy will design and produce ultrathin, flexible printed batteries that are especially designed to power IoT devices integrated with Semtech’s LoRa devices and wireless RF technology (LoRa Technology). LoRa Technology, with its long-range, low-power capabilities, is regarded by many as the defacto platform for building low-power wide area networks (LPWAN).

ImprintTo help accelerate a next generation of battery technology, Semtech has invested in Imprint Energy. The companies are working closely to target applications that have the potential to create entirely new markets. The Imprint Energy battery enables new applications which have a thin and small form factor and due to the integrated manufacturing process, the batteries are low cost to produce, making high volume deployments feasible.

A key benefit of the Imprint Energy battery technology is the ability to be printed using multiple types of conventional high-volume printing equipment; this enables quick integration by traditional electronic manufacturers in their existing production lines. Test production runs are currently being processed and the resulting batteries are being used in applications prototypes to validate assumptions and engage early adopters.

Imprint Energy | www.imprintenergy.com

Semtech | www.semtech.com

Antenna Measurement Made Easy

For web Lacoste Lead Image

Covering the Basics

If you’re doing any kind of wireless communications application, that probably means including an antenna in your design. The science of antennas is complex. But here Robert shows how the task of measuring an antenna’s performance is less costly and exotic than you’d think.

By Robert Lacoste

Now that wireless communications is ubiquitous, chances are you’ll be using Bluetooth, Wi-Fi, cellular, LoRa, MiWi or other flavor of wireless interface in your next design. And that means including an antenna. Unfortunately, antenna design is not an easy topic. Even very experienced designers sometimes have had to wrestle with unexpected bad performances by their antennas. Case in point: Google “iPhone 4 antenna problem” and you will get more than 3 million web pages! In a nutshell, Apple tried to integrate a clever antenna in that model that was threaded around the phone. They didn’t anticipate that some users would put their fingers exactly where the antenna was the most sensitive to detuning. Was it a design flaw? Or a mistake by the users? It was hotly debated, but this so-called “Antennagate” probably had significant impact on Apple’s sales for a while.

I already devoted an article to antenna design and impedance matching (“The Darker Side: Antenna Basics”, Circuit Cellar 211, February 2008). Whether you include a standard antenna or design your own, you will never be sure it is working properly until you measure its actual performance. Of course, you could simply evaluate how far the system is working. But how do you go farther if the range is not enough? How do you figure out if the problem is coming from the receiver, the transmitter, propagation conditions or the antenna itself? My personal experience has been that the antenna is very often the culprit. With that in mind, it really is mandatory to measure whether or not an antenna is behaving correctly. Take a seat. This month, I will explain how to easily measure the actual performance of an antenna. You will see that the process is quite easy and that it won’t even need costly or exotic equipment.

SOME ANTENNA BASICS

Let’s start with some basics on antennas. First, all passive antennas have the same performance whether transmitting or receiving. For this article, I’ll consider the antenna as transmitting because that’s easier to measure. Let’s consider an antenna that we inject with a given radio frequency power Pconducted into its connector. Where will this power go? First off, impedance matching should be checked. If the impedance of the antenna is not well matched to the impedance of the power generator, then a part of the power will be reflected back to the generator. This will happen in particular when the transmit frequency is not equal to the resonant frequency of the antenna. In such a case, a part of Pconducted will be lost.  That is known as mismatch losses: Pavailable= Pconducted – MismatchLosses. While that itself is a very interesting subject, I have already discussed impedance matching in detail in my February 2008 article. I also devoted another article to a closely linked topic: standing waves. Standing waves appear when there is a mismatch. The article is “The Darker Side: Let’s play with standing waves” (Circuit Cellar 271, February 2013).

For the purpose of discussion here, I will for now assume that there isn’t any mismatching—and therefore no mismatch loss. …

Read the full article in the October 327 issue of Circuit Cellar

We’ve made the October 2017 issue of Circuit Cellar available as a sample issue. In it, you’ll find a rich variety of the kinds of articles and information that exemplify a typical issue of the current magazine.
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