Microcontroller

Just as you put all the major components of a Desktop PC on to a Single Board Computer (SBC) if you put all the major components of a Single Board Computer on to a single chip it will be called as a Microcontroller. Because of the limitations in the VLSI design most of the input/output functions exist in a simplified manner. Typical architecture of such a microprocessor is shown in Fig. 4.2.




* The double-lined blocks are core to the processor. Other blocks are on-chip.

The various units of the processors (Fig. 4.2) are as follows:

o The C500 Core contains the CPU which consists of the Instruction Decoder, Arithmetic Logic Unit (ALU) and Program Control section.

o The housekeeper unit generates internal signals for controlling the functions of the individual internal units within the microcontroller.

o Port 0 and Port 2 are required for accessing external code and data memory and for emulation purposes.

o The external control block handles the external control signals and the clock generation.

o The access control unit is responsible for the selection of the on-chip memory resources.

o The IRAM provides the internal RAM which includes the general purpose registers.

o The XRAM is another additional internal RAM sometimes provided.

o The interrupt requests from the peripheral units are handled by an Interrupt Controller Unit.

o Serial interfaces, timers, capture/compare units, A/D converters, watchdog units (WDU), or a multiply/divide unit (MDU) are typical examples for on-chip peripheral units. The external signals of these peripheral units are available at multifunctional parallel I/O ports or at dedicated pins.


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