18 Feb 12

STMicroelectronics has come up with a new method for data storage with a dual-interface wireless EEPROM memory IC, the M24LR16E.

This device can operate normally with a standard low power I2C interface or it can switch over to a 13.56-MHz ISO15693 contactless RF interface for wireless communication.

The antenna used for the two-way data transfer in the RF interface mode has a dual purpose. Beyond transfering data, its second purpose is to harvest ambient energy in the RF signal being transmitted, and use that to supply its own power, and convert the excess into a voltage output that may be used to power other electronic components.

While operating in the RF energy harvesting mode and I2C disabled, an entire low-power system can be powered directly from harvested RF energy. No battery or external power supply would be required for this, since no power would be needed on the Vcc pin. In case the RF field strength is insufficient or when the energy harvesting mode is disabled, the analog output pin Vout goes into high-Z state and the energy harvesting mode is automatically stopped.

Using this device would simplify the development and maintenance of many applications, as the need for batteries, power cables, and data lines is eliminated. This would have potential for many new applications, as new designs can be much smaller and lighter, and much less expensive. It is possible for a system to become virtually maintenance-free by using this method.

Some of the potential applications would include e-paper devices such as electronic shelf labels, sensing and monitoring systems, industrial automation, and personal healthcare products. It is anticipated that this type of device would be widely used in RFID/NFC-compatible devices as RFID is becoming standardized in supply-chain and retail businesses. NFC technology is another possibility, as it is estimated to be used in more than 500 million mobile phones sold annually by 2015.

The power management circuitry integrated in the M24LR16E makes the extra harvested energy available to other devices on the board through an output pin. The nominal output voltage output on this pin is between 1.7 and 2.3V, which is sufficient to power a few low-power ICs, such as CMOS chips. The maximum output current on this pin can be configured from 300µA to 6mA by setting bits in an internal register.

The M24LR16E-R also features a user configurable digital out pin (RF WIP/BUSY) that can be used to drive a micro controller interrupt input pin.  This pin is activated only when power is applied to the Vcc pin, and can be set to toggle for RF write in progress, or RF busy (command in progress), depending on the mode selected.

The EEPROM memory in the M24LR16E is 16Kbits, and it is organized as 2048 x 8 bits in the I2C mode and 512 x 32 bits in the ISO 15693 and ISO 18000-3 mode 1 RF mode.

The memory device includes a data protection scheme to protect stored data against threats such as accidental over-writing and unauthorized access or tampering. There are several password protection options included, up to 32 bits.

The device operates at a 1.8V to 5.5V supply-voltage range and is available in SO8, TSSOP8 or MLP8 surface-mount packages. The antenna required for wireless operation can simply be etched on the printed circuit board.

12 Feb 12

Wireless sensor and actuator systems using energy harvesting have the potential to achieve a huge green impact in future applications, as they could eliminate the need for battery charging systems, battery replacement, maintenance and disposal problems. Not only would they eliminate battery problems, but wiring and connector problems when interfacing between various sensors, actuators, and other low-power device are eliminated also. This can save a lot of trouble while being very cost effective, as wiring, connectors, and batteries can be very expensive and troublesome. Another huge advantage is that sensors and actuators can now be placed in previously inaccessible locations.

ST Microelectronics has teamed up with Araymond, a supplier to the automotive and solar industries, and Micropelt GmbH, of Freiburg, Germany to provide thermal-energy harvesting-based solutions to power ‘smart sensors’ and ‘smart microsystems’.

Micropelt is known for the development of the world’s smallest and most effective thermoelectric elements for micro energy harvesting, thermal sensing, cycling and cooling. Micropelt has developed chip-sized thermogenerators (TEGs) which converts the waste energy as heat is transferred from a higher temperature to a lower temperature into electrical energy, and they have been able to achieve the highest power density available packed into a few square millimeters of footprint. They accomplish this with a patented scalable thin film micro-structuring platform technology using the ‘Seebeck Effect’, which maximizes power density for energy harvesting, cooling or thermal cycling while minimizing component size. Batteries may now eventually become obsolete as free electricity from waste heat can power wireless sensor networks and ultra-low-power systems for their entire life.

ST has focused on providing energy storage components that would support this new energy harvesting technology. They supply the rechargeable battery used in the TE-Power NODE kit, which is the EFL700A39 EnFilm thin film solid state battery, with a 700-microamp-hour rating. This battery can supply an inrush current up to 10mA. ST also provides a battery board which contains the EnFilm battery and the electronic circuitry that controls and monitors both battery charge level and the energy balance.

Their combined efforts resulted in the development of evaluation system featuring ST’s new long-life EnFilm rechargeable battery combined with Micropelt’s Thermal Electrical Generator (TEG) chip. This system is called the TE-Power NODE evaluation kit, and demonstrates a new type of virtual wireless perpetual-energy solution with long-life and maintenance-free operation.

Micropelt has designed custom power conditioning circuitry which controls the generated thermoelectric power so that it provides sufficient power to drive a wireless sensor node and charge a battery using its excess thermal energy.  Within the TE-Power NODE evaluation kit, the Micropelt TEG MPG-D751 is housed between a solid Aluminium base plate and a finned heatsink. The base is attached to a suitable heat source, so the cooling effect of the heat sink creates a temperature difference which is used to generate electrical power through the TEG. When the base plate is in contact with a heat source, the TEG provides power to the system and recharges the EnFilm. When the heat source is removed, the TEG stops and only the EnFilm battery provides power to the wireless sensor. The battery is also needed to supply the occasional pulses of higher current.

Micropelt has included a versatile ultra-low power 2.4 GHz wireless link to its custom designed graphical user interface in the wireless sensor module. Power management and charge monitoring circuitry in the TE-Power NODE evaluation kit connect to the included graphical user interface software using the wireless link.  The software can display and log important thermal and electrical system parameters, and maintains a continuously measured power balance between the TEG and the EnFilm battery.

There is a growing trend towards the use of wireless sensor networks, and they would be useful in applications like process automation, condition monitoring, and smart buildings. As energy harvesting becomes more widely used, free electrical energy can be extracted from many other sources where thermoelectric power isn’t readily available, such as vibration, light, and RF energy.

11 Feb 2012

Resistive touch interfaces have become very popular as a standard user interface in many applications because they provide of easier integration, lower total system cost and simpler input with finger, glove, or stylus. These are now widely used in applications such as medical devices, industrial controls, handwriting or signature capture, point of sale terminals, tablet displays, and many other kinds of touch-input devices.

The new mTouch AR1100 Analogue Resistive USB Touch-Screen Controller introduced by Microchip is a single-chip plug and play solution that provides these advantages along with universal support for a wide array of touch screen manufacturers. Based on the AR1000 Analog Resistive Touch-Screen Controller series, the AR1100 controller offers high performance with advanced calibration capabilities as a USB mouse or single-input digitizer. There are calibration options for alignment and linearization, which enables higher accuracy for 4-, 5- and 8-wire touch screens, as well as accurate button pressing for critical applications with tight board spacing.

No configuration is necessary as the AR1100 is designed to be a fully-functioning touch controller on power-up. The device can dynamically adapt to various touch screen electrical characteristics such as sensitivity, contact resistance, and capacitance for optimal performance. Very little extra hardware is needed for this universal controller and the device will automatically detect the communication mode (either USB or UART) and configure itself accordingly. If USB is detected, AR1100 automatically defaults to a mode that is compatible with the intrinsic drivers of standard operating systems. Additionally, the USB mode will enumerate as HID-MOUSE, which is the default device type. There are also two other device types (HID-GENERIC and HID-DIGITIZER), which can be set by the configuration command and is saved in nonvolatile memory. Any desired modifications to the operating parameters of the touch screen can also be easily saved to internal nonvolatile memory to override the defaults. A jumper on the MODE pin is all that is needed to select the sensor type (either 5-Wire or 4/8-Wire).

Microchip's mTouch AR1100 Development Kit (DV102012) provides all that designers need to get started using AR1100 analog resistive touch controllers as a turnkey, cost effective touch solution. The kit includes an AR1100 production-ready PCB, USB and serial communication cables, a 5-wire 7” touch screen, and extra touch screen pin-out adapter cables that designers can use to quickly connect and test almost any 4, 5, or 8 wire touch screen. A CD is also included with the full suite of AR1100 utilities and all the documentation for the chip and board options of the AR1100 touch screen controller.

With free drivers for most major operating systems, the AR1100 enables designers to quickly create low-risk touch interface solutions. The AR1100 controller is available immediately in 20-pin SOIC, SSOP and QFN packages and is also available as a board product.

1 Feb 12

At Embedded Adventures, when we're prototyping things, we use bucket loads of jumper wires.

As far as we're concerned, you can never have enough jumper wires. Or LEDs. But especially jumper wires. So we bought so many of them, we're surrounded by them.  In order to get through the stock pile so we can get out the door, we've reduced the price on these guys so you can enjoy them too.  Premium connecters and cable, so they can carry more current, these are an essential tool for prototying.

We use male headers on the PCB, then use female jumper wires to connect them together.  Some boards we've seen have female headers on them, though in which case male jumper wires are handy. A combination of both, of course, allows you to make arbitrarily long connections.  We also carry 2-way, 4-way and 6-way jumper wires as well that save having to plug and unplug individual connectors - ideal for connecting several boards together.

Grab them while they're hot!

25 Jan 11

A new SCR made by STMicroelectronics, the TN1205H, can reduce heat sink costs and footprint layout on a PCB with its high junction temperature rating of 150 C and high turn-off capabilities. The higher junction temperature rating is achieved with a higher current density and circuit design can be optimized with a choice of many current ratings. The device comes standard with a 12A RMS on-state current rating (8A average) and a 600V off-state voltage rating. The sensitive gate trigger current is as low as 5mA with maximum trigger voltage of 1.3V.

These devices would be a perfect fit for many applications that need over-voltage crowbar protection as they would easily be able to handle large voltage and/or current surges without any concern about overheating. These devices can also provide protection from inrush currents when a device is turned on.

Of course, the TN1205H can be used in general purpose AC line load switching applications, motor control circuits, small home appliances, and lighting systems. Because of the higher temperature rating, the devices could be used in many applications with insufficient ventilation or high ambient temperature in the surroundings. Some examples here would be capacitive discharge ignition circuits, ATV or motorbike voltage regulators, and power tools.

The through-hole or surface-mount package styles bring high performance into applications where space is very limited.

STMicroelectronics has introduced a high speed voltage comparator which it claims has the industry's best ratio of current consumption to response time. ST’s TS3011 single comparator achieves a propagation delay of 8ns while consuming only 470 µA of supply current at 5V. According to ST, this is 50% lower than other solutions in the market.

ST’s new high-speed voltage comparator has been designed to address applications where fast response time is critical, such as data communications equipment and other signal-conditioning applications in the telecom and industrial fields. In many data processing applications with a noisy signal, the minimized delay helps ensure instant data recovery and maintain error-free communication traffic flow.

Fast-response comparators can also find use in pulse-width modulation for audio amplifiers or as output buffers in oscilloscopes and analog-to-digital converters. The TS3011 includes push-pull outputs, removing the need for a pull up resistor, and rail to rail inputs.

Specified for a supply voltage of 2.2 to 5 V, this comparator can provide a stable response time over a wide temperature range of -40°C to +125°C. It has enhanced ESD capabilities and a latch-up immunity of 200mA. The device comes in space-saving SMD packages (SOT23-5 and SC70-5).