Fundamentals of Microcontroller

It can be implemented using high level language or assembly language. Clock speed determines how much processing can be accomplished in a given amount of time by the MCU.Some have a narrow clock speed range. Sometimes a specific clock frequency is chosento generate another clock required in the system, e.g. for serialbaud rates. Generally the higher clock frequencies, the higher the system costs because not only does the it cost more, butso do all the support chips required, such as RAMs, ROMs and bus drivers.

The processing technology of the microcontroller are N-channel metaloxidesemiconductor (NMOS) or high-density complementarymetal-oxide semiconductor (HCMOS).In HCMOS, signals drive from rail-to-rail, unlike earlier NMOSprocessors. Since these criteria can significantly affect noise issues insystem design, HCMOS uses less power and thus generates less heat.The design geometries in HCMOS are smaller, which permit denserdesigns for a given size and thus allow higher bus speeds. The denserdesigns also allow lower cost, for more units can be processed on thesame sized silicon wafer. For these reasons, most MCUs today areproduced using HCMOS technology.

Advantages of Microcontroller compared to Microprocessor

The advantages of microcontroller are that all MCUs have on-chip resources to achieve a higher levelof integration and reliability at a lower cost. An on-chip resource is ablock of circuitry built into the MCU which performs some useful functionunder control of the MCU. Built-in resources increase reliability becausethey do not require any external circuitry to be working for the resourceto function. They are pre-tested by the manufacturer and conserve boardspace by integrating the circuitry into the MCU.

Some of the more popular on-chip resources are memory devices,timers, system clock/oscillator, and I/O. Memory devices includeread/write memory (RAM), read-only memory (ROM), erasableprogrammable ROM (EPROM), electrically erasable programmableROM (EEPROM), and electrically erasable memory (EEM). The termEEM actually refers to an engineering development version of an MCUwhere EEPROM is substituted for the ROM to reduce development time.

Timers include both real-time clocks and periodic interrupt timers. Other timer functions includetimer compare and/or input capture lines.

I/O includes serial communication ports, parallel ports (I/O lines), analog-todigital(A/D) converters, digital-to-analog (D/A) converters, liquid crystaldisplay drivers (LCD), and vacuum fluorescent display drivers (VFD).

Other built-in resources may include computer operating properly (COP) watchdog system which can be hardware or software based.

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