A Microcontroller (MCU for microcontroller unit) is a small computer on a single metal-oxide - semiconductor(MOS) Integrated chip(IC) chip. In modern terminology, it is similar to, but less sophisticated than, a system on a chip (SoC); a SoC may include a microcontroller as one of its components.
- A microcontroller contains one or more CPUs (processor cores) along with memory and programmable input/output peripherals. Program memory in the form of ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a small amount of RAM.
- Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips.
Types of microcontroller.
As of 2008, there are several dozen microcontroller architectures and vendors including:
- ARM Core processor (many vendors)
- ARM cortex - M coresare specifically targeted toward microcontroller applications
- MicrochipTechnology Atmel AVR (8-bit), AVR32 (32-bit), and AT91SAM (32-bit)
- Cypress semiconductor's M8C core used in their PSoC (Programmable System-on-Chip)
- Freescale coldFire(32-bit) and S08 (8-bit)
- Freescale 68HC11(8-bit), and others based on the Motorola 6800 family
- Inlet 8051, also manufactured by NXP Semiconductors, Infineon and many others
- Infineon: 8-bit XC800, 16-bit XE166, 32-bit XMC4000 (ARM based Cortex M4F), 32-bit TriCore and, 32-bit Aurix Tricore Bit microcontrollers[34]
- Maxim integratedMAX32600, MAX32620, MAX32625, MAX32630, MAX32650, MAX32640
- MIPS
- Microchip Technology PIC, (8-bit PIC16, PIC18, 16-bit dsPIC33 / PIC24), (32-bit PIC32)
- NXPSemiconductors LPC1000, LPC2000, LPC3000, LPC4000 (32-bit), LPC900, LPC700 (8-bit)
- Parallax propeller
- Power PC ISE
- Rabbit2000 (8-bit)
- Renesas Electronics: RL78 16-bit MCU; RX 32-bit MCU; SuperH; V850 32-bit MCU; H8; R8C 16-bit MCU
- Silicon Laboratories Pipelined 8-bit 8051 microcontrollers and mixed-signal ARM-based 32-bit microcontrollers
- STMicroelectronics STM8 (8-bit), ST10 (16-bit), STM32 (32-bit), SPC5 (automotive 32-bit)
- Texas instruments TI MSP430 (16-bit), MSP432 (32-bit), C2000 (32-bit)
- Toshiba TLCS-870 (8-bit/16-bit)
Many others exist, some of which are used in very narrow range of applications or are more like applications processors t
It may used in :
- Microcontrollers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, microcontrollers make it economical to digitally control even more devices and processes.
- Mixed signal microcontrollers are common, integrating analog components needed to control non-digital electronic systems. In the context of the internet of things, microcontrollers are an economical and popular means of data collection, sensing and actuating the physical world as edge devices.
- Some microcontrollers may use four-bit words and operate at frequencies as low as 4 kHz, for low power consumption (single-digit milliwatts or microwatts). They generally have the ability to retain functionality while waiting for an event such as a button press or other interrupt; power consumption while sleeping (CPU clock and most peripherals off) may be just nanowatts, making many of them well suited for long lasting battery applications. Other microcontrollers may serve performance-critical roles, where they may need to act more like a digital signal processor (DSP), with higher clock speeds and power consumptionhan microcontrollers.
- A microcontroller can be considered a self-contained system with a processor, memory and peripherals and can be used as an embedded system.[28] The majority of microcontrollers in use today are embedded in other machinery, such as automobiles, telephones, appliances, and peripherals for computer systems.
Embedded system.
While some embedded systems are very sophisticated, many have minimal requirements for memory and program length, with no operating system, and low software complexity. Typical input and output devices include switches, relays, solenoids, LED's, small or custom liquid-crystal displays, radio frequency devices, and sensors for data such as temperature, humidity, light level etc. Embedded systems usually have no keyboard, screen, disks, printers, or other recognizable I/O devices of a personal computer, and may lack human interaction devices of any kind.
Interrupt.
Microcontrollers must provide real-time (predictable, though not necessarily fast) response to events in the embedded system they are controlling. When certain events occur, an interrupt system can signal the processor to suspend processing the current instruction sequence and to begin an interrupt service routine (ISR, or "interrupt handler") which will perform any processing required based on the source of the interrupt, before returning to the original instruction sequence.
Development :
One book credits TI engineers Gary Boone and Michael Cochran with the successful creation of the first microcontroller in 1971. The result of their work was the TMS 1000, which became commercially available in 1974. It combined read-only memory, read/write memory, processor and clock on one chip and was targeted at embedded systems.[5]
History :
During the early-to-mid-1970s, Japanese electronics manufacturers began producing microcontrollers for automobiles, including 4-bit MCUs for in-car entertainment, automatic wipers, electronic locks, and dashboard, and 8-bit MCUs for engine control.[6]
Volume and cost :
In 2002, about 55% of all CPUs sold in the world were 8-bit microcontrollers and microprocessors.[11]
Over two billion 8-bit microcontrollers were sold in 1997,[12] and according to Semico, over four billion 8-bit microcontrollers were sold in 2006.[13] More recently, Semico has claimed the MCU market grew 36.5% in 2010 and 12% in 2011.[14]
A typical home in a developed country is likely to have only four general-purpose microprocessors but around three dozen microcontrollers. A typical mid-range automobile has about 30 microcontrollers. They can also be found in many electrical devices such as washing machines, microwave ovens, and telephones.
