Author Archives: Noel D

What is I3C Interface Communication

I2C is a popular serial communication protocol, with I3C being an improved version. Embedded systems use this new protocol for achieving significantly higher data throughput and features that are more advanced than what I2C offers. Designers and engineers can use I3C for improving the functioning and performance of their designs while adding more features such as in-band interrupts, hot-join, and high data rate modes. With I3C being backward compatible, it can communicate with legacy targets using the present I2C protocol.

There are some major differences between I3C and I2C. While I2C works on bus speeds of 100 kHz, 400 kHz, or 1 MHz, I3C operates with bus speeds up to 12.5 MHz. The increase is due to I3C using push-pull outputs, which switch between push-pull drivers and open-drain outputs depending on the state of the bus. I3C uses open-drain driving during arbitration or initial addressing where multiple targets are controlling the line at the same time. I3C uses the push-pull driver for unidirectional communication, and no other device is expected to communicate simultaneously.

The voltage range of operation of I2C is between 3.3 and 5 VDC, and I3C operates with supply voltages of 1.2, 1.8, and 3.3 VDC, with the possibility of other voltages in between. Unlike 12C, I3C does not require external pull-up resistors, as the main controller on the bus provides these.

I2C uses static 7-bit and 10-bit addressing of target devices. On the other hand, I3C makes use of dynamic 7-bit addressing, where the active controller designates each target with an unambiguous address to prevent collisions with addressing. In contrast, I2C requires the designer to keep track of the current addresses to prevent assigning the same address to two or more devices. I3C assigns addresses dynamically during bus initialization.

I2C has no mechanism for a target to tell the controller that data is ready unless it uses an extra IO line. However, devices in I3C can signal an interrupt by using the serial data and serial clock lines, thereby making the protocol truly two-wire. I3C also uses this in-band signaling for implementing hot-join functionality. This allows new devices to join once the initial address assignment is over.

I2C allows multi-controller buses. Here, although multiple devices can operate as controllers, only one of them can actively communicate at a time. On the other hand, I3C can have only one active controller, while other capable devices can request to become active controllers on the bus. This device can then become the secondary controller. If the secondary controller is no longer acting as an active controller, it starts functioning as an I3C target.

I3C is backward compatible with I2C. However, for successful communication, the targets in the I2C protocol must have a 7-bit address, and must not use clock stretching. The new protocol suggests the I2C targets contain 50ns filters on their inputs. By meeting these requirements, I2C targets become compatible with the I3C bus. On the other hand, a few I3C devices may also operate as I2C targets, until they have been assigned a dynamic address. When working in the I2C mode, the I3C devices have static communication addresses.

New Graphene Sensors

While more advanced technology sectors have been late in adopting graphene, it finds plenty of interest in both lower- and high-tech applications. One of these applications is sensors based on graphene. Different industry sectors have steadily been using these sensors.

This is because graphene can be the basis of an effective sensing platform. Several interesting applications manifest this in many ways. Of these, the biosensor subsector is especially notable in attracting heavy investment. This trend is likely to continue even beyond 2022.

With graphene properties being exhaustively documented, many are now aware that they can do a lot with graphene and that many applications can benefit from its properties. Although many of these aspects are often subject to some hype, the fundamental properties of graphene make it a superior material of choice. This is primarily of account of graphene being suitable as an active sensing surface in many sensing applications.

The major advantage of graphene is its inherent thinness. This allows sensing devices made from graphene to be far more flexible and smaller in comparison to many other materials. In addition, graphene forms a very high-end active surface area.

In applications involving sensing, a high surface area is beneficial as it allows interaction with a larger range of molecules like different gases, water, biomolecules, and many other molecular stimuli. With graphene being an active surface, it is possible to attach a number of different molecular receptors and molecules to a sheet of graphene. This helps to create sensors that can detect specific molecules.

However, graphene has more advantages. Because of the high electrical conductivity of graphene, its high charge transfer properties, and high charge carrier mobility, sensors made from graphene exhibit very high sensitivity. That means, graphene sensors will generate a detectable response even from a small interaction with the environment. This happens because the excellent properties of graphene help in changing the resistivity across the graphene sheet with each small interaction. Therefore, graphene sensor help to detect even the smallest amounts of stimuli from the environment.

Because of their innate thinness, it is possible to make graphene-based sensors in small form factors, while retaining their highly sensitive sensing characteristics. It is also possible to tailor the sensors chemically for detecting a range of stimuli from the environment. This characteristic has led to the generation of much commercial interest in developing various graphene-based sensors for a variety of commercial markets involving many applications.

For instance, Paragraf has a graphene-based Hall-effect sensor that can measure changes in a magnetic field using the Hall effect. Therefore, this has increased the possibility of adding many new and interesting application areas to those that graphene sensors had not ventured into so far.

In the past year, Paragraf has demonstrated that Hall-effect sensors based on graphene are highly sensitive. They can measure currents flowing in batteries within electric vehicles for monitoring their status. Paragraf makes these sensors by depositing single layers of contamination-free graphene directly on a wafer. They repeat this following standard semiconductor manufacturing processes. This has allowed them to make several volume applications possible now, including those for fast and sensitive biosensors for detecting biomarkers within liquid samples.

Haptic Skin Sensors

Although great technological advances are taking place to engage our eyes and ears in the virtual worlds, engaging other senses like touch is a different ballgame altogether. At City University in Hong Kong, engineers have developed a wearable, thin electronic skin called WeTac. It offers tactile feedback in AR and VR.

At present, there are several wearable devices with designs that allow users to manipulate virtual objects while receiving haptic feedback from them. However, not only are these devices heavy and big but also require tangles of wire and complex setups.

In contrast, the WeTac system is one of the neatest arrangements among all others. The engineers have made it from a rubbery hydrogel that makes it stick to the palm and on the front of the fingers. The device connects to a small battery and has a Bluetooth communications system that sits on the forearm in a 5-square-centimeter patch. The user can recharge the battery wirelessly.

The hydrogel has 32 electrodes embedded in it. The electrodes are spread out all over the palm, the thumb, and the fingers. The system sends electrical currents through these electrodes to produce tactile sensations.

According to the WeTac team, they can stimulate a specific combination of these electrodes at varying strengths. This allows them to simulate a wide range of experiences. They have demonstrated this by simulating catching a tennis ball or generating the feel of a virtual mouse moving across the hand. They claim they can ramp up the sensation to uncomfortable levels, but not to the extent of making them painful. This can give negative feedback, such as a reaction to touching a digital cactus.

According to the researchers, they can pair the system up with either augmented or virtual reality. They can thus simulate some intriguing use cases. For instance, it is possible to feel the rhythm of slicing through VR blocks in Beat Saber, or catch Pokemon while petting a Pikachu in the park in AR.

Using the WeTac system, it may be possible to control robots remotely or transmit to the human operator the tactile sensations of the robot as it grips something.

Syntouch has a new tactile sensor that performs three important functions. First, it measures the impedance using a flexible bladder placed against an array of sensing electrodes fixed in a rigid core. This arrangement helps to measure deformity, somewhat like the human finger, using its ductile skin and flesh against the rigid bone structure inside it. The finger uses its fingernails to cause bulges in the skin for detecting shear forces.

Second, the tactile sensor registers micro-vibrations using a pressure sensor that the sensor core has mounted on its inside. This enables measurements of surface texture and roughness. The fingerprints are very crucial here, as they can interact with the texture.

Third, the sensor has a thermistor. Its electrical resistance is a function of temperature. Just like the human finger can sense heat, the sensor also generates heat, while the thermistor allows it to detect how it exchanges this heat when the finger touches an object.

Using Ferrites in Wire Assemblies

The phenomenon of magnetism is prevalent all over the world, along with related concepts like the magnetic field, electromagnetism, and electromotive force. Although these are complex subjects at a higher level, they are easy to understand. However, these are principles on which electric motors operate, the earth’s magnetosphere shields life, and refrigerator doors remain closed.

The wonderful properties of magnetism also help products and applications like cable assemblies. There are well-known magnets like those made of neodymium, and these are permanent magnets with inherent magnetic properties. They comprise elements of Neodymium, Boron, and Iron. Neodymium magnets are among the most powerful permanent magnet types available. In comparison, there are non-permanent magnets also. Typically known as electromagnets, they derive their properties from the passage of an electrical current.

Other types of permanent magnets are also available. The most popular of these is the ferrite magnets, and industries use them for a lesser-known reason. Used in various forms like chokes, cores, and beads, these inexpensive devices greatly help filter electrical noise and get products to comply with EMI/EMC regulations. Countless design applications use them in different form factors and are available from numerous manufacturers. Ferrite magnets comprise a mixture of iron oxide and ceramic magnets. In doughnut-like shapes, they keep control over signal integrity within bundles of wire. For instance, a data cable carrying high-frequency data transmission,  when routed through the magnetic field of a ferrite, can eliminate unwanted electrical noise, as the ferrite acts as a passive EMI filter.

For a ferrite to be effective, the cable must pass through the center of the ferrite and its magnetic field. Looping and routing the wire multiple times through the ferrite helps incrementally improve the signal integrity. While a majority of cables have their wires passing through the ferrites only once, some designs require them to make as many as three loops to meet design objectives. Typically, there are two types of ferrites available that are suitable for cable assemblies—snap-on ferrites and doughnut ferrites.

Snap-on ferrites are the easiest to assemble. These are passive suppression devices with two halves. A plastic clamshell case holds the two halves as it snaps close around the wire. Available in a wide variety of sizes for different cable diameters and performance types, these are excellent devices that can mix and match various types of ferrite to help pass an aggressive test requirement. However, snap-on ferrites can be expensive and require accurate sizing to match the wire’s outer diameter to create an interference fit. As their design is like a clamshell, it is easy to remove snap-on ferrites.

Doughnut ferrites are simpler, being in the shape of a ring or a doughnut. The cable must pass through the center of the continuous circle of the ferrite before the wires terminate into a connector. The doughnut ferrite is therefore a permanent fixture, unlike the snap-on ferrite that the user can remove at any time. Overmolding the ferrite helps to fix its position on the cable while protecting the brittle ferrite magnet from damage.

What are Spring-Loaded Connectors

Selecting the right spring-loaded connectors saves not only expenses in the long-term, but reputations as well. In most key applications, reliably machined pin contacts can significantly reduce the total cost of ownership.

Industrial applications are cost-sensitive. Hence, designers tend to specify solutions that cost the lowest. However, while ensuring the price of their solution is competitive, designers must also ensure their company remains profitable. This is because a low-cost, low-quality connector solution can easily lead to premature failure and considerable re-work costs, while possibly damaging reputations.

This is where machined pin spring-loaded connectors come in. There are numerous ways in which these precision-made interconnects can provide better solutions while improving efficiency, and lowering overall costs.

In a spring-loaded connector, the main components are the spring-loaded pins—also known as pogo pins, spring probes, or spring pins. They provide highly reliable interconnecting solutions for a wide variety of demanding applications. In typical spring-loaded connectors, manufacturers provide precision-machined contacts to ensure low resistance, high quality, and compliance.

Spring-loaded contacts typically comprise three or more separate machined components, assembled with an internal spring. Manufacturers precision-machine these components from brass and electroplate them with gold for ensuring excellent electrical conductivity, corrosion resistance, and durability. They assemble these contacts into high-temperature insulators to produce spring-loaded connectors in various configurations. In the market, these connectors are available in SMT, through-hole, and wire termination styles. They are also available in horizontal or vertical orientations.

At working travel, contact resistance is typically less than 20 milliohms, while the current capacity can range from 2-9 A continuous. Most manufacturers offer connectors they rate for 100,000 to 1 million cycles, with an operating temperature range covering -55 °C to +125 °C—depending on application variables like exposure time.

Precision machining is the most reliable and flexible method of making pins for connectors. The process delivers not only high quality but is also repeatable while offering material flexibility and versatile design. The process creates high-precision pins with cylindrical geometry, which are also known as turned pins. Precision machining is highly accurate and remarkably consistent. It can hold critical feature tolerances to +/- 0.0005”(0.0127 mm) or better.

Designers often have an incorrect perception that machined spring-loaded pins are high-cost solutions, beyond their budgets. The basis of their perception is the high-quality processes and materials manufacturers employ in the connectors. While there is justification for higher piece-part costs, the overall price of the connector is lower because of the several benefits and features the spring-loaded pins provide.

For instance, a spring-loaded pin may be simply contacting a pad on a mating PCB. The diameter of the mating pad provides the amount of positional tolerance that the spring-loaded pin can tolerate. Consequently, the spring-loaded pin solution offers tolerances in the x, y, and z directions. This ensures not only better overall functionality, but also reduces assembly time. Moreover, the Bill of Materials has only one part number instead of two.

Many designs today feature a packed occurrence with a lack of visibility in the connection area, typically known as blind mating. Here again, positional tolerances offer an advantage to the spring-loaded pins and connectors.