Microcontroller is a computer on a chip that is programmed to perform almost any control, sequencing, monitoring and display function. Because of its relatively low cost, it is a natural choice for design. It performs many of the functions traditionally done by simple logic circuitry, requential control circuits, timers or a small microcomputer
Kind or Type of Microcontroller:1. PIC
PIC microcontrollers from Microchip are very popular microcontrollers. PICs are easily programmable cheap microcontrollers. PIC is the name for the Microchip microcontroller (MCU) family, consisting of a microprocessor, I/O ports, timer(s) and other internal, integrated hardware. The main advantages are low external part count, a wide range of chip sizes (from 8-pin up), great availability of compilers and source code and easy programming. Flash-type devices are reprogrammable in-circuit, while OTP versions are very cheap to use at the final stage. A wide range of simple programmer hardware and software is downloadable from the net. PIC16F84 seems to be the "standard" for small gadgets you see in the web projects. If you are a beginner with PICs, a PIC 16F84A or 16F628 device is a good choice to start with. With a PIC microcontroller you can do things that would be difficult to do with discrete logic. Besides its power, you can easily "change your mind" with a microcontroller. The PIC isn't for every project. It won't replace a PC, or even a larger processor. But for many jobs it is just the right size, inexpensive, and doesn't require much in the way of support hardware. Many electronics hobbyist have used PICs because they are quite easy to start with and easy to get. There are many different varieties of PICs that run at many frequencies. There are many versions, because in hardware design you may need a certain combination of features and this will dictate what PIC you select. For a beginner there is really only two choices:The most commonly used PIC controller within electronics hobbyists seems to be PIC 16F84A (the most popular starter PIC, 18 pin IC). PIC 16F87x is few dollars more expensive version that had a plethora of features including analog to digital converters, a UART, and more. PIC 16F87x comes in 40 or 28 pin case depending on chip version. PICs are also used on some commercial devices. Here is where the dive variety of versions come to the use. There are several steps you need to take to get started: Select a PIC, assemble the tools you need (software and programmer) and learn to program. If you want a good learning experience, you can download a free simulation environment from Microchip and practice programming without spending any money or buying any chips at all. When you have some real application, then you can buy the chips you need. There are many different varieties of PICs that run at many frequencies.
8051/8052
The 8051 is an 8 bit microcontroller originally developed by Intel in 1980. It is the world's most popular microcontroller core, made by many independent manufacturers. A typical 8051 contains CPU with boolean processor, 5 or 6 interrupts, 2 or 3 16-bit timer/counters, programmable full-duplex serial port, 32 I/O lines, RAM and ROM/EPROM in some models. The 8051 architecture is quite strange and original. One strong point of the 8051 is the way it handles interrupts. Vectoring to fixed 8-byte areas is convenient and efficient.The 8051 instruction set is optimized for the one-bit operations so often desired in real-world, real-time control applications. The 8051 has the widest range of variants of any embedded controller on the market. The smallest device is the Atmel 89c1051, a 20 Pin FLASH variant with 2 timers, UART, 20mA. The most powerful chip is the Infineon Technologies 80C517A, with 32 Bit ALU, 2 UARTS, 2K RAM, PLCC84 package, 8 x 16 Bit PWMs, and other features.
There are also other similar microcontrollers around. 80C31 microcontroller is the version of the 80C51 without ROM. The 80C31 is a widely available (it?s produced by several manufacturers). The 80C31 has 128 bytes of RAM, two external interrupt pins, two timer/counters, and serial ports. It has 32 I/O pins, but doesn?t have ROM, so some of the ports (namely ports 0 and 2) are used for the address bus and data bus. The 80C31 is a high-quality microcontroller for embedded design considering its instruction set and price. Atmel AT89C2051 microprocessor is a quite widely used a 20 pin 8051 variant, with FLASH (reprogrammable) program memory.
68HC11
The 68hc11 is a powerful 8-bit data, 16-bit address microcontroller from Motorola with an instruction set that is similar to the older 68xx (6801, 6805, 6809) parts.
There are several different varieties of 68HC11 microcontroller. Depending on the variety, the 68hc11 has built-in EEPROM/OTPROM, RAM, digital I/O, timers, A/D converter, PWM generator, and synchronous and ansynchronous communications channels (RS232 and SPI). This is a general overview of those subsystems:
- Main timer system comprises of a single 16 bit counter clocked at the E clock (2,3,or 4 Mhz - there is a programmable prescaler to slow it down is required). From this single counter run a number of input capture and output compare registers
- The A-D Convertor on ICs that have it is typically 8 channel 8 bit A/D (although the G5 has a 10 bit A/D)
- Serial Communications Interface (SCI) supports data format 1 Start, 8 or 9 data, and one stop bit at 150 - 312500 Baud data rate.
- Serial Peripheral Interface (SPI) comprises CLK, DATA IN, DATA OUT and optionally chip selects. As well as using specific SPI devices, it is very easy to expand IO using the SPI and standard logic devices (e.g. 74HC595 and 74HC165).
Typical current draw of 68HC11 system is less than 10mA.
4. Scenix microcontrollersScenix is known for making high performance PIC microcontroller clones. The SX PIC clones are interesting because they provide much more computing power than the Microchip PICs but are programmed using the same commands. On the downside the SX'es do not provide much peripherals (only a comparator and a timer). Scenix is now known as Ubicom.
5. SGS-Thomson microcontrollers
6. ARM
ARM is the industry's leading provider of 16/32-bit embedded RISC microprocessor solutions used in embedded applications. The company licenses its high-performance, low- cost, power-efficient RISC processors, peripherals and system-on-chip (SoC) designs to leading international electronics companies. ARM designs CPUs, peripherals and chips which are licensed to semiconductor partners for manufacture, supply and support, either in SoCs or standard parts. ARM does not manufacture silicon. ARM processors are frequently used in devices like PDAs, cellular phones and networking devices. Typical operating ystems used in those devices are Linux, PalmOS, SymbianOS and WindowsCE. ARMxTDMI is a general-purpose RISC architecture, but it is frequently used in applications demanding low-to-moderate DSP performance. ARM's inclusion of enhanced DSP functionality with the ARM9E is in response to growing customer demand for greater signal processing capabilities from ARM cores. Adding DSP functionality to an embedded general-purpose processor can potentially eliminate the need for a separate DSP.
7. Atmel Microcontroller
Atmel manufactures three families of microcontrollers: the popular 8051, the AT91 which is an ARM Thumb, and the Atmel AVR 8-bit RISC devices. Flash varieties are available. Wide development tools support is available for the 8051 & AT91; support for the AVR is building.
Atmel has several microcontroller families:
- 89 Series: ATMEL 89 Series Flash Microcontrollers are microcontrollers based on 8051 microcontroller architecture and Flash memory.
- AVR Series: AVR-Single-Chip-Processors AT90Sxxxx are excellent for homebrewing every kind of processor-driven electronics. AVR controllers have typically few kilobytes of memory (1-8 typically), UART and SPI interface.
- TinyAVR Series: The tinyAVR? Flash-based microcontroller family is priced at less than a dollar in high volume, and offers an unrivaled combination of price, performance and flexibility. The available memory is typically 1-2 kilobytes.
- ATMega Series: This is a powerful microcontroller with lots of on-chip memory (16-128 kilobytes). ATmega series controllers typically have JTAG and SPI interfaces.
For many processors assembly has to be lerned in order to program these devices. For several controller models there is also C compiler available.
8. Hitachi
9. Zilog
ZiLOG provides of 8-bit Flash microcontroller solutions. ZiLOG, a design solutions company specializing in embedded and integrated circuits, is an innovator in the development, design, and manufacturing of application specific standard products (ASSPs) for the data communication, peripherals, and consumer product markets.
The Zilog Z80 is an 8-bit microprocessor designed and manufactured by Zilog from 1976 onwards. It was widely used both in desktop and embedded computer designs, and is one of the most popular CPUs of all time. The Z80 microprocessor is an 8 bit CPU with a 16 bit address bus capable of direct access of 64k of memory space. It has a language of 252 root instructions and with the reserved 4 bytes as prefixes, acceses an additional 308 instructions. The Z80 was modeled after the 8088 and contains the 78 - 8088 opcodes as a subset to it's language.
Although Zilog made several attempts to move off the Z80 onto more powerful 16-bit (Zilog Z800, Zilog Z8000) and 32-bit (Zilog Z80000) platforms, other companies were offering CPUs in this performance range years earlier, and the Zilog chips never caught on.
9. Picaxe
PICAXE microcontrollers are exciting, low-cost, re-programmable chips that can be used as low-cost 'brains' in many kinds of electronic project. The unique feature of the PICAXE system is that programs are downloaded via a direct cable link straight into the microcontroller, so no expensive programmers or erasers are required. The software is free, and so this low cost approach also means that students can use the whole programming system at home.
10. Rabbit Controller
Rabbit microprocessors are high-performance, low-EMI devices designed for embedded control and communications where Ethernet connectivity is needed. Rabbit 2000 is a low-cost microprocessor designed specifically for embedded systems. Rabbit 3000 is a low EMI microprocessor designed for embedded control, communications, and Ethernet connectivity.
Source : Edited from epanorama.net
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