• 27May

    Semiconductors are crystalline or amorphous solids with distinct electrical characteristics. They are of high resistance – higher than typical resistance materials, but still of much lower resistance than insulators. Their resistance decreases as their temperature increases, which is behavior opposite to that of a metal. Finally, their conducting properties may be altered in useful ways by the deliberate, controlled introduction of impurities (“doping”) into the crystal structure, which lowers its resistance but also permits the creation of semiconductor junctions between differently-doped regions of the extrinsic semiconductor crystal. The behavior of charge carriers which include electrons, ions and electron holes at these junctions is the basis of diodes, transistors and all modern electronics.

    Semiconductor devices can display a range of useful properties such as passing current more easily in one direction than the other, showing variable resistance, and sensitivity to light or heat. Because the electrical properties of a semiconductor material can be modified by doping, or by the application of electrical fields or light, devices made from semiconductors can be used for amplification, switching, and energy conversion.

    The modern understanding of the properties of a semiconductor relies on quantum physics to explain the movement of charge carriers in a crystal lattice. Doping greatly increases the number of charge carriers within the crystal. When a doped semiconductor contains mostly free holes it is called “p-type”, and when it contains mostly free electrons it is known as “n-type”. The semiconductor materials used in electronic devices are doped under precise conditions to control the concentration and regions of p- and n-type dopants. A single semiconductor crystal can have many p- and n-type regions; the p–n junctions between these regions are responsible for the useful electronic behavior.

    Although some pure elements and many compounds display semiconductor properties, silicon, germanium, and compounds of gallium are the most widely used in electronic devices. Elements near the so-called “metalloid staircase”, where the metalloids are located on the periodic table, are usually used as semiconductors.

    Some of the properties of semiconductor materials were observed throughout the mid 19th and first decades of the 20th century. The first practical application of semiconductors in electronics was the 1904 development of the Cat’s-whisker detector, a primitive semiconductor diode widely used in early radio receivers. Developments in quantum physics in turn allowed the development of the transistor in 1947 and the integrated circuit in 1958.

    The global semiconductors market has been volatile over many years. Setting up a chip fabrication industry requires the investment of billions of dollars. The cyclic fluctuations in demand and supply have caused significant fluctuations in price and margin.

  • 27May

    The AVR32 is a 32-bit RISC microcontroller architecture produced by Atmel. The microcontroller architecture was designed by a handful of people educated at the Norwegian University of Science and Technology, including lead designer Øyvind Strøm, PhD and CPU architect Erik Renno, M.Sc in Atmel’s Norwegian design center.

    Most instructions are executed in a single-cycle. The multiply–accumulate unit can perform a 32-bit × 16-bit + 48-bit arithmetic operation in two cycles (result latency), issued once per cycle.

    It does not resemble the 8-bit AVR, except that they were both designed at Atmel Norway, in Trondheim. Some of the debug-tools are similar.

    The AVR32 has at least two micro-architectures, the AVR32A and AVR32B. These differ in the instruction set architecture, register configurations and the use of caches for instructions and data.

    The AVR32A CPU cores are for inexpensive applications. They do not provide dedicated hardware registers for shadowing the register file, status and return address in interrupts. This saves chip area at the expense of slower interrupt-handling.

    The AVR32B CPU cores are designed for fast interrupts. They have dedicated registers to hold these values for interrupts, exceptions and supervisor calls. The AVR32B cores also support a Java virtual machine in hardware.

    The AVR32 instruction set has 16-bit (compact) and 32-bit (extended) instructions, with several specialized instructions not found in the MIPS32, ARMv5 or ARMv6. Several U.S. patents are filed for the AVR32 ISA and design platform.

    Just like the AVR 8-bit microcontroller architecture, the AVR32 was designed for high code density (packing much function in few instructions) and fast instructions with few clock cycles. Atmel used the independent benchmark consortium EEMBC to benchmark the architecture with various compilers and consistently outperformed both ARMv5 16-bit (THUMB) code and ARMv5 32-bit (ARM) code by as much as 50% on code-size and 3× on performance.[citation needed]

    Atmel says the “picoPower” AVR32 AT32UC3L consumes less than 0.48 mW/MHz in active mode, which it claimed, at the time, used less power than any other 32-bit CPU. Then in March 2015, they claim their new Cortex-M0+-based microcontrollers, using ARM Holdings’ ARM architecture, not their instruction set, “has broken all ultra-low power performance barriers to date.”

  • 27May

    The AVR is a modified Harvard architecture 8-bit RISC single-chip microcontroller, which was developed by Atmel in 1996. The AVR was one of the first microcontroller families to use on-chip flash memory for program storage, as opposed to one-time programmable ROM, EPROM, or EEPROM used by other microcontrollers at the time.

    The AVR architecture was conceived by two students at the Norwegian Institute of Technology (NTH),Alf-Egil Bogen and Vegard Wollan.

    The original AVR MCU was developed at a local ASIC house in Trondheim, Norway, called Nordic VLSI at the time, now Nordic Semiconductor, where Bogen and Wollan were working as students.[citation needed] It was known as a μRISC (Micro RISC)[citation needed] and was available as silicon IP/building block from Nordic VLSI.[citation needed] When the technology was sold to Atmel from Nordic VLSI,[citation needed] the internal architecture was further developed by Bogen and Wollan at Atmel Norway, a subsidiary of Atmel. The designers worked closely with compiler writers at IAR Systems to ensure that the instruction set provided for more efficient compilation of high-level languages. Atmel says that the name AVR is not an acronym and does not stand for anything in particular. The creators of the AVR give no definitive answer as to what the term “AVR” stands for. However, it is commonly accepted that AVR stands for Alf (Egil Bogen) and Vegard (Wollan)’s RISC processor. Note that the use of “AVR” in this article generally refers to the 8-bit RISC line of Atmel AVR Microcontrollers.

    Among the first of the AVR line was the AT90S8515, which in a 40-pin DIP package has the same pinout as an 8051 microcontroller, including the external multiplexed address and data bus. The polarity of the RESET line was opposite (8051’s having an active-high RESET, while the AVR has an active-low RESET), but other than that the pinout was identical.

    The AVR 8-bit microcontroller architecture was introduced in 1997. By 2003, Atmel had shipped 500 million AVR flash microcontrollers.

 
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