MCU – Microcontroller Unit – 1
MCU  1 cip or VLSI core –
application-specific
• Embedded system: is a system whose
principal function is not computational, but
which is controlled by a computer embedded
within it.
Examples: Refrigerator
Examples: Car Door
Examples: Derbot Autonomous Guided
Vehicle
Examples: Derbot Autonomous Guided
Vehicle
• The microprocessor is a processor on one
silicon chip.
• The microcontrollers are used in embedded
computing.
• The microcontroller is a microprocessor with
added circuitry.
Microcontrollers
Microcontroller Packaging and Appearance
From left to right: PIC 12F508, PIC 16F84A, PIC 16C72,
Motorola 68HC05B16, PIC 16F877, Motorola 68000
Some slides above are from - Dr. Gheith Abandah
Types of MCU
– 8/16/32-bit mcu – internal bus & instruction size, ALU
– Instruction sets – RISC/CISC
• Complicated instruction set comp [CISC]
– It has an instruction set that supports many addressing modes.
– It offers flexibility in choosing various ways of performing the data
transfer and ALU ops.
• Reduced ISC [RISC]
– Supports 1/2 addressing modes
– Need many registers – so need less fetching from external
memories for operations… so higher performance in computing
than CISC… e.g., ARM
Types of MCU
– Memory architecture
• Harvard mem  has a distinct mem address space for
i. Program mem &
ii. Data mem
 It has separate instructions ,
 hence separate control signal[s], for data transfers
from these two memories.
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Princeton mem  has a common mem space for
both. So no need for separate …
Types of MCU
– Family
• 8051
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Intel
Philips
Atmel
Siemens
Dallas
Motorola
PIC - Peripheral Interface Controller
Hitachi
Texas
ARM - Advanced RISC Machine (previously known as Acorn RISC
Machine)
• Others
Selection of MCU
• Checklist
– 8/16/32 bit ALU
– Max. power dissipation
– Clock speed needed
– Instructions set  RISC/CISC
Selection of MCU…
• Checklist –
– Memory architecture
– Memory size
– Cache, memory management unit, DSP
calculations
– Internal PROM/…
– I/O ports
– Cost
Selection of MCU…
• Additional checklists
– Cost when single chip and when MCU interfaces
to circuit with some features
– Major building blocks of hardware cost and
availability
– Major building blocks of software cost and
availability
– Ease of integration
– Design team expertise
– Manpower
Applications
Numerous! e.g.,
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Biomedical instruments
Communication systems
Controller
Instrumentations
Control systems
Automotive apps, etc.
• Program mem – mainly Volatile / ROM
• Data mem - non-volatile mem / RAM
Intel 8051/8031 architecture
• CPU has the control and sequencing logic
circuits, ALU, Flags, clock
• Program mem - ROM
• Interrupt control ckt
• Internal timing devices – timer
• Serial interface
• Data mem - RAM
Intel 8051/8031…
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Special function registers
Ports
Register banks – 4 set of registers
RST – reset pin
INT – interrupt pins
VCC – voltage supply pin
GND