First what is a microcontroller? It is is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications.(Wikipedia)

Today, we have more than 30 microcontroller manufacturers with many microcontroller products in the world today. They are listed below:

AMCC

PowerPC 403

PowerPC 405

PowerPC 440

Altera

Nios II 32-bit configurable soft microprocessor

Nios 16-bit configurable soft processor

Analog Devices

ADSP-21xx digital signal processor

MicroConverter series – ARM7 and 8052 cores

Atmel

AT89 series

AT90, ATtiny, ATmega, ATxmega series

AT91SAM (ARM architecture)

AVR32 (32-bit AVR architecture)

MARC4

Charmed Labs

Qwerk

XPort

Cypress Semiconductor

CY8C2xxxx

CY8C3xxxx

CY8C5xxxx

Dallas Semiconductor

8051 Series

MAXQ series

Secure Micros series

ELAN Microelectronics Corp.

EM78PXXX Low Pin-Count series

EM78PXXXN GPIO series

EM78PXXXN ADC Type MCU series

Energy Micro AS

Standard microcontrollers

Application specific microcontrollers

Custom microcontrollers

EPSON Semiconductor

4-bit Microcomputers S1C60/62/63 family

8-bit Microcomputers S1C88 family

16-bit Microcomputers S1C17 family

32-bit Microcomputers S1C33 family

Freescale Semiconductor

8-bit

68HC05 (CPU05)

68HC08 (CPU08)

68HC11 (CPU11)

16-bit

68HC12 (CPU12)

68HC16 (CPU16)

Freescale DSP56800 (DSPcontroller)

32-bit

Freescale 683XX

M·CORE

MPC500

MPC 860 (PowerQUICC)

MPC 8240/8250 (PowerQUICC II)

MPC 8540/8555/8560 (PowerQUICC III)

Fujitsu

F²MC Family (8/16-bit)

FR Family (32-bit)

FR-V Family (32-bit RISC)

Holtek

HT48FXX Flash I/O type series

HT48RXX I/O type series

HT46RXX A/D type series

HT49RXX LCD type series

HT82XX Computer Peripheral series

HT95XX Telecom Peripheral series

HT86XX Voice series

Infineon

8-bit

XC800 family

16-bit

XE166 family

C166 family

C167 family

32-bit

TRICORE family

Intel

8-bit

MCS-48

MCS-51

8xC251

16-bit

MCS-96 (8096 family – also incl. 8061)

Intel MCS-296

Lattice Semiconductor

Mico8 8-bit

Mico32 32-bit

Microchip Technology

8-bit PICmicro

PIC10 and PIC12

PIC16 series

PICAXE

PIC18 series

PIC24

32-bit

PIC32MX series

National Semiconductor

COP400

COP8

CR16

SC/MP

NEC

17K

V25

75X

78K

V850

Parallax

SX

SX-18, 20, 28, 48 and 52 versions with speed up to 75 MHz (75 MIPS)

Propeller

NXP Semiconductors

8-bit

80C51

16-bit

XA

32-bit

ARM7

LPC2000

ARM9

LPC3000

ARM Cortex-M4

LPC4300

ARM Cortex-M3

LPC1700/LPC1300/LPC1800

ARM Cortex-M0

LPC1100/LPC1200

Rabbit Semiconductor

Rabbit 2000

Rabbit 3000

Rabbit 4000

Renesas Electronics

4-bit

720

8-bit

78K

SLP

740

16-bit

M16C

H8

R8C

32-bit

SuperH

V850

RX

SiLabs

C8051F300

C8051F120

Silicon Motion

SM2XX family

SM321

SM323

SM323E

SM324

SM330

SM501

SM712

SM722

SM340

SM350

SM370

Sony

SPC900 Series

SPC970 Series

SR11 Series

STMicroelectronics

ST6 (8-bit)

ST7 (8-bit)

STM8 (8-bit)

?PSD (8-bit)

ST10 (16-bit)

STM32 (ARM Cortex M3, 32-bit)

STR7 (ARM7TDMI, 32-bit)

STR9 (ARM966E-S, 32-bit)

Texas Instruments

TMS370 (8-bit)

MSP430 (16-bit)

TMS320F28xx (32-bit)

C2000 (32-bit, Real-time control)

Stellaris (32-bit, ARM Cortex-M3)

TMS570 (32-bit RISC, ARM Cortex-R4)

Toshiba

TLCS-47 (4-bit)

TLCS-870 (8-bit)

TLCS-900 (16 and 32-bit CISC)

TX19A (32-bit RISC)

Ubicom

IP2022

IP3022

Xemics

XE8000 8-bit

Xilinx

Microblaze 32-bit

Picoblaze 8-bit

XMOS

XCore XS1 32-bit

ZiLOG

Zilog Z8 – 8-bit

Zilog Z180

Zilog eZ8

Zilog eZ80

Zilog Z16

Why do we have many different Microcontrollers?

Like there are so many different car manufacturers, Toyota, Honda, Mercedes and so on, so also are many manufacturers of microcontrollers. After the idea of having a programmable device, many electronics manufacturers took the idea to develop their own chip. The internal architecture therefore differs among the manufacturers in a little ways. So learning one microcontroller facilitates learning the other. Moreover the same company manufactures many different microcontrollers, which are all almost compatible. In electronics, the requirements of projects vary; for example to make a security device, you need little memory, whereas to make a data logger you need lots of memory.

A remote control will not need to display data on LCD, so needs lesser number of I/O lines, whereas an industrial control unit will need to display its data, and therefore needs more I/O lines. A calculator needs only digital input, whereas a temperature controller needs to acquire analog data. These differences in requirements, makes the manufacturers produce different microcontrollers with different memory size, number of I/O lines and number of integrated peripheral devices. Otherwise they are all similar to use. Again, if you have mastered one microcontroller, it’s easy to migrate to another. So the type of microcontroller to be used in a given project will be determined by the exact requirements.

Microprocessor vs. Microcontroller

Essentially these two devices are similar, but with a little bit of difference. The microcontroller contains the same main elements as any computer system:

• Central processing unit (CPU)

• Memory

• Input/Output

In a PC, these are provided as separate chips, linked together via bus connections on board, but under the control of the microprocessor (CPU). A bus is a set of lines which carry data in parallel form which are shared by the peripheral devices. The PC can be modified to suit a particular application, by changing the type of CPU, size of memory and selection of input/output (I/O) devices tailored to the system requirements. A microcontroller on the other hand will contain, the CPU, RAM, ROM, Timers, I/O etc. all packed within one integrated circuit. This facilitates the development process, as well as reduces the requirements of external components. In microcontroller, you cannot change the number and type of integrated devices. This means that the MCU for a particular application must be chosen to suit the application at the design level from the available range of microcontrollers. In any given circuit, the microcontroller has a single dedicated function in contrast to the PC that is multifunctional. Single task application in which microcontrollers are deployed is a type of system referred to as embedded system because they are often embedded in many devices.

Central processing unit (CPU)

In a microcontroller system, a CPU block is in charge of all input, output, calculations and control. This cannot operate without a program, which is a list of instructions that is held in memory. The program consists of a sequence of binary codes that are fetched from memory by the CPU in sequence, and executed. The instructions are stored in numbered memory locations, and copied to an instruction register in the CPU via the data bus. Decoding the instruction is a hardware process, using a block of logic gates to set up the control lines of the processor unit, and fetching the instructions.

Memory

There are two types of memory: volatile and non-volatile. Volatile memory loses its data when switched off, but can be written by the CPU to store current data; this is RAM (Random Access Memory). ROM (Read Only Memory) is non-volatile, and retains its data when switched off. In a microcontroller, we have Electrically Erasable Programmable Read Only Memory (EEPROM) which is used in storing data during power down; for example, a security code or combination for an electronic lock. The ideal memory is non-volatile, read and write, fast, large and cheap. Unfortunately, it does not exist! The main trade-off is cost, size and speed of access. Flash ROM, as used in memory sticks and MP3 players, is closest to the ideal, having the advantages of being non-volatile and rewritable. This is why it is used as program memory in microcontrollers which need to be reprogrammed.

Input and Output

In microcontrollers, ports (input and output) are based on a data register, and set of control registers, which pass the data in and out in a controlled manner, often according to a standard protocol (method of communication). There are two main types of port: parallel and serial. In a parallel port, the data is usually transferred in and out 8 bits at a time, while in the serial port it is transmitted 1 bit at a time on a single line.

Existing microcontrollers in the world market today? Next series (Part 3)