05-01-2012, 11:16 AM
[attachment=15867]
Microcontrollers
A Microcontroller is essentially a small and selfsufficient
computer on a chip, used to control devices
It has all the memory and I/O it needs on board
Is not expandable – no external bus interface
Characteristics of a Microcontroller
• Low cost, on the order of $1
• Low speed, on the order of 10 KHz – 20 MHz
• Low Power, extremely low power in sleep mode
• Small architecture, usually an 8-bit architecture
• Small memory size, but usually enough for the type of
application it is intended for. Onboard Flash.
• Limited I/O, but again, enough for the type of application
intended for
Microprocessors
A Microprocessor is fundamentally a collection of
on/off switches laid out over silicon in order to perform
computations
Characteristics of a Microprocessor
• High cost, anywhere between $20 - $200 or more!
• High speed, on the order of 100 MHz – 4 GHz
• High Power consumption, lots of heat
• Large architecture, 32-bit, and recently 64-bit architecture
• Large memory size, onboard flash and cache, with an
external bus interface for greater memory usage
• Lots of I/O and peripherals, though Microprocessors tend
to be short on General purpose I/O
Harvard Architecture
Harvard Architecture refers to a memory structure
where the processor is connected to two different
memory banks via two sets of buses
This is to provide the processor with two distinct data
paths, one for instruction and one for data
Through this scheme, the CPU can read both an
instruction and data from the respective memory
banks at the same time
This inherent independence increases the throughput
of the machine by enabling it to always prefetch the
next instruction
The cost of such a system is complexity in hardware
Commonly used in DSPs
Von-Neumann Machine
A Von-Neumann Machine, in contrast to the Harvard
Architecture provides one data path (bus) for both
instruction and data
As a result, the CPU can either be fetching an
instruction from memory, or read/writing data to it
Other than less complexity of hardware, it allows for
using a single, sequential memory.
Today’s processing speeds vastly outpace memory
access times, and we employ a very fast but small
amount of memory (cache) local to the processor
Modern processors employ a Harvard Architecture to
read from two instruction and data caches, when at the
same time using a Von-Neumann Architecture to access
external memory
Microcontrollers
A Microcontroller is essentially a small and selfsufficient
computer on a chip, used to control devices
It has all the memory and I/O it needs on board
Is not expandable – no external bus interface
Characteristics of a Microcontroller
• Low cost, on the order of $1
• Low speed, on the order of 10 KHz – 20 MHz
• Low Power, extremely low power in sleep mode
• Small architecture, usually an 8-bit architecture
• Small memory size, but usually enough for the type of
application it is intended for. Onboard Flash.
• Limited I/O, but again, enough for the type of application
intended for
Microprocessors
A Microprocessor is fundamentally a collection of
on/off switches laid out over silicon in order to perform
computations
Characteristics of a Microprocessor
• High cost, anywhere between $20 - $200 or more!
• High speed, on the order of 100 MHz – 4 GHz
• High Power consumption, lots of heat
• Large architecture, 32-bit, and recently 64-bit architecture
• Large memory size, onboard flash and cache, with an
external bus interface for greater memory usage
• Lots of I/O and peripherals, though Microprocessors tend
to be short on General purpose I/O
Harvard Architecture
Harvard Architecture refers to a memory structure
where the processor is connected to two different
memory banks via two sets of buses
This is to provide the processor with two distinct data
paths, one for instruction and one for data
Through this scheme, the CPU can read both an
instruction and data from the respective memory
banks at the same time
This inherent independence increases the throughput
of the machine by enabling it to always prefetch the
next instruction
The cost of such a system is complexity in hardware
Commonly used in DSPs
Von-Neumann Machine
A Von-Neumann Machine, in contrast to the Harvard
Architecture provides one data path (bus) for both
instruction and data
As a result, the CPU can either be fetching an
instruction from memory, or read/writing data to it
Other than less complexity of hardware, it allows for
using a single, sequential memory.
Today’s processing speeds vastly outpace memory
access times, and we employ a very fast but small
amount of memory (cache) local to the processor
Modern processors employ a Harvard Architecture to
read from two instruction and data caches, when at the
same time using a Von-Neumann Architecture to access
external memory
