Field programmable gate arrays (FPGAs) vs. microcontrollers: What’s the difference?

Field
programmable
gate
arrays
(FPGAs)
and

microcontroller
units
(MCUs)
are
two
types
of
commonly
compared
integrated
circuits
(ICs)
that
are
typically
used
in
embedded
systems
and
digital
design.
Both
FPGAs
and
microcontrollers
can
be
thought
of
as
“small
computers”
that
can
be
integrated
into
devices
and
larger
systems.

As
processors,
the
primary
difference
between
FPGAs
and
microcontrollers
comes
down
to
programmability
and
processing
capabilities.
While
FPGAs
are
more
powerful
and
more
versatile,
they
are
also
more
expensive.
Microcontrollers
are
less
customizable,
but
also
less
costly.
In
many
applications,
microcontrollers
are
exceptionally
capable
and
cost-effective.
However,
for
certain
demanding
or
developing
applications,
like
those
requiring
parallel
processing,
FPGAs
are
necessary.

Unlike
microcontrollers,
FPGAs
offer
reprogrammability
on
the
hardware
level.
Their
unique
design
allows
users
to
configure
and
reconfigure
the
chip’s
architecture
depending
on
the
task.
FPGA
design
can
also
handle
parallel
inputs
simultaneously,
whereas
microcontrollers
can
only
read
one
line
of
code
at
a
time.
An
FPGA
can
be
programmed
to
perform
the
functions
of
a
microcontroller;
however,
a
microcontroller
cannot
be
reprogrammed
to
perform
as
an
FPGA. 

What
is
a
field
programmable
gate
array
(FPGA)?

First
introduced
by
manufacturer
Xilinx
in
1985,
FPGAs
are
highly
valued
for
their
versatility
and
processing
power.
As
a
result,
they
are
a
preferred
choice
in
many

high-performance
computing
(HPC),
digital
signal
processing
(DSP)
and
prototyping
applications.

Unlike
traditional
application-specific
integrated
circuits
(ASICs),
FPGAs
are
designed
to
be
configured
(and
reconfigured)
“in
the
field”
after
the
initial
manufacturing
process
is
complete.
While
customization
is
the
FPGAs
greatest
value
offering,
it
should
be
noted
that
FPGAs
not
only
allow
for
programmability,
they
require
it.
Unlike
ASICs,
FPGAs
are
not
“out-of-the-box”
solutions,
and
they
must
be
configured
prior
to
use
with
a
hardware
description
language
(HDL),
such
as
verilog
or
VHDL.
Programming
an
FPGA
requires
specialized
knowledge,
which
can
increase
costs
and
delay
deployments.
While
some
FPGAs
do
offer
non-volatile
memory
that
can
retain
programming
instructions
when
powered
off,
typically
FPGAs
must
be
configured
on
start-up.  

FPGA
benefits

Despite
these
challenges,
FPGAs
remain
useful
in
applications
requiring
high-performance,
low-latency
and
real-time
flexibility.
FPGAs
are
particularly
well
suited
for
applications
requiring
the
following:

• 
  Rapid
  prototyping:
  FPGAs
  can
  be
  quickly
  configured
  into
  multiple
  types
  of
  customized
  digital
  circuits,
  allowing
  for
  expedited
  deployments,
  assessments
  and
  modifications
  without
  the
  need
  for
  costly
  and
  time-consuming
  fabrication
  processes. 
• 
  Hardware
  acceleration:
  Demanding
  applications
  benefit
  from
  the
  FPGA’s
  parallel-processing
  capabilities.
  FPGAs
  may
  offer
  significant
  performance
  improvements
  for
  computationally
  intensive
  tasks,
  such
  as
  signal
  processing,
  
  cryptography,
  and
  
  machine
  learning
  algorithms.
• 
  Customization:
  FPGAs
  are
  a
  flexible
  hardware
  solution
  that
  can
  be
  easily
  optimized
  to
  meet
  specific
  project
  requirements. 
• 
  Longevity:
  FPGA-based
  designs
  may
  benefit
  from
  a
  longer
  hardware
  lifespan
  as
  FPGAs
  can
  be
  updated
  and
  reconfigured
  to
  meet
  evolving
  project
  demands
  and
  technology
  standards. 

FPGA
components

To
achieve
reconfigurability,
FPGAs
are
composed
of
an
array
of
programmable
logic
blocks
interconnected
by
a
programmable
routing
fabric.
The
main
components
of
a
typical
FPGA
are
as
follows:

• 
  Configurable
  logic
  blocks
  (CLBs):
  CLBs
  provide
  compute
  functionality
  and
  may
  contain
  a
  small
  number
  of
  primitive
  logic
  elements,
  such
  as
  logic
  gates,
  small
  look-up
  tables
  (LUTs),
  multiplexors
  and
  flip-flops
  for
  data
  storage. 
• 
  Programmable
  interconnects:
  Made
  up
  of
  wire
  segments
  joined
  by
  electrically
  programmable
  switches,
  these
  linkages
  provide
  routing
  pathways
  between
  the
  various
  FPGA
  resources,
  allowing
  for
  different
  configurations
  and
  the
  creation
  of
  custom
  digital
  circuits. 
• 
  I/O
  Blocks
  (IOBs):
  The
  interface
  between
  an
  FPGA
  and
  other
  external
  devices
  is
  enabled
  by
  input
  output
  (I/O)
  blocks,
  which
  allow
  the
  FPGA
  to
  receive
  data
  from
  and
  control
  peripherals 

FPGA
use
cases

Versatile
by
nature,
FPGAs
are
common
among
a
wide
variety
of
industries
and
applications:

• 
  Aerospace
  and
  defense:
  Offering
  high-speed
  parallel
  processing
  valuable
  for
  data
  acquisition,
  FPGAs
  are
  a
  preferred
  choice
  for
  radar
  systems,
  image
  processing
  and
  secure
  communications. 
• 
  Industrial
  control
  systems
  (ICS):
  Industrial
  control
  systems
  used
  to
  monitor
  infrastructure—like
  power
  grids,
  oil
  refineries
  and
  water
  treatment
  plants—use
  FPGAs
  that
  can
  be
  easily
  optimized
  to
  meet
  the
  unique
  needs
  of
  various
  industries.
  In
  these
  critical
  industries,
  FPGAs
  can
  be
  used
  to
  implement
  various
  automations
  and
  hardware-based
  encryption
  features
  for
  efficient
  cybersecurity.
• 
  ASIC
  development:
  FPGAs
  are
  often
  used
  in
  the
  prototyping
  of
  new
  ASIC
  chips. 
• 
  Automotive:
  Advanced
  signal
  processing
  also
  makes
  FPGAs
  well-suited
  for
  automotive
  applications,
  including
  advanced
  driver
  assistance
  systems
  (ADAS),
  sensor
  fusion
  and
  GPS.
• 
  Data
  centers:
  FPGAs
  add
  value
  to
  
  data
  centers
  by
  optimizing
  high-bandwidth,
  low-latency
  servers,
  networking
  and
  storage
  infrastructure.

FPGA
features

• 
  Processing
  core:
  Configurable
  logic
  blocks
• 
  Memory:
  External
  memory
  interface 
• 
  Peripherals:
  Configurable
  I/O
  blocks
• 
  Programming:
  Hardware
  description
  language
  (VHDL,
  Verilog) 
• 
  Reconfigurability:
  Highly
  reconfigurable,
  reprogrammable
  logic

What
is
a
microcontroller?

Microcontrollers
are
a
type
of
compact,
ready-made
ASIC
containing
a
processor
core
(or
cores),
memory
(RAM),
and
erasable
programmable
read-only
memory
(EPROM)
for
storing
the
custom
programs
that
run
on
the
microcontroller.
Known
as
a
“system-on-a-chip
(SoC)”
solution,
microcontrollers
are
essentially
small
computers
integrated
into
a
single
piece
of
hardware
that
can
be
used
independently
or
in
larger
embedded
systems. 

Consumer-grade
microcontrollers,
such
as
the
Arduino
Starter
Kit
or
Microchip
Technology
PIC,
can
be
configured
using
assembly
language
or
common
programming
languages
(C,
C++),
and
they
are
favored
by
hobbyists
and
educators
for
their
cost-effective
accessibility.
Microcontrollers
are
also
capable
of
handling
more
complex
and
critical
tasks
and
are
common
in
industrial
applications.
However,
decreased
processing
power
and
memory
resources
can
limit
the
microcontroller’s
efficacy
in
more
demanding
applications. 

Microcontroller
benefits

Despite
their
limitations,
microcontrollers
offer
many
advantages,
including
the
following:

• 
  Compact
  design:
  Microcontrollers
  integrate
  all
  necessary
  components
  onto
  a
  small,
  single
  chip
  offering
  a
  small
  footprint
  valuable
  in
  applications
  where
  size
  and
  weight
  are
  a
  priority. 
• 
  Energy
  efficiency:
  Designed
  to
  operate
  on
  low
  power,
  microcontrollers
  are
  well
  suited
  for
  battery-powered
  devices
  and
  other
  applications
  where
  power
  consumption
  is
  a
  concern.
• 
  Cost-effective:
  Microcontrollers
  offer
  a
  complete
  SoC
  solution
  that
  reduces
  the
  need
  for
  additional
  peripherals
  and
  components.
  Low-cost,
  general-purpose
  microcontrollers
  can
  greatly
  reduce
  overall
  project
  expenses. 
• 
  Flexibility:
  Although
  not
  as
  versatile
  as
  FPGAs,
  microcontrollers
  are
  programmable
  for
  a
  wide
  range
  of
  various
  applications.
  While
  they
  cannot
  be
  reprogrammed
  on
  the
  hardware
  level,
  microcontrollers
  can
  be
  easily
  reconfigured,
  updated
  and
  optimized
  on
  a
  software
  level. 

Microcontroller
components

When
reprogrammability
is
not
a
priority,
self-contained
microcontrollers
offer
a
compact
and
capable
alternative.
The
following
are
the
key
components
of
a
microcontroller: 

• 
  Central
  processing
  unit
  (CPU):
  Colloquially
  referred
  to
  as
  the
  “brain,”
  the
  
  central
  processing
  unit
  (CPU)
  serves
  as
  the
  core
  component
  responsible
  for
  executing
  instructions
  and
  controlling
  operations.  
• 
  Memory:
  Microcontrollers
  contain
  both
  volatile
  memory
  (RAM),
  which
  stores
  temporary
  data
  that
  may
  be
  lost
  if
  the
  system
  loses
  power,
  and
  non-volatile
  memory
  (ROM,
  FLASH)
  for
  storing
  the
  microcontroller’s
  programming
  code.
• 
  Peripherals:
  Depending
  on
  the
  intended
  application,
  a
  microcontroller
  may
  contain
  various
  peripheral
  components,
  such
  as
  input/output
  (I/O)
  interfaces
  like
  timers,
  counters,
  analog-to-digital
  converters
  (ADCs)
  and
  communication
  protocols
  (UART,
  SPI,
  I2C).

Microcontroller
use
cases

Unlike
FPGAs,
small,
affordable,
and
non-volatile
microcontrollers
are
ubiquitous
in
modern
electronics,
frequently
deployed
for
specific
tasks,
including
the
following:

• 
  Automotive
  systems:
  Microcontrollers
  are
  used
  in
  engine
  control,
  airbag
  deployment
  and
  in-car
  infotainment
  systems.  
• 
  Consumer
  electronics:
  Microcontrollers
  are
  critical
  to
  smartphones,
  smart
  TVs
  and
  other
  home
  appliances,
  especially
  devices
  that
  integrate
  into
  the
  
  Internet
  of
  Things
  (IoT).
• 
  Industrial
  automation:
  Microcontrollers
  are
  well-suited
  to
  industrial
  applications,
  such
  as
  controlling
  machinery,
  monitoring
  systems
  and
  process
  automation. 
• 
  Medical
  devices:
  Microcontrollers
  are
  often
  deployed
  in
  life-saving
  devices,
  such
  as
  pacemakers,
  blood
  glucose
  monitors
  and
  diagnostic
  tools. 

Microcontroller
features

• 
  Processing
  core:
  Fixed
  CPU
• 
  Memory:
  Integrated
  RAM
  and
  ROM/Flash 
• 
  Peripherals:
  Built-in
  I/O
  interfaces
  for
• 
  Programming:
  Software
  (C,
  Assembly) 
• 
  Reconfigurability:
  Limited,
  firmware
  updates

Key
differences
between
FPGAs
and
microcontrollers

When
comparing
FPGAs
and
microcontrollers,
it
is
important
to
consider
a
number
of
key
differences,
including
hardware
architecture,
processing
capabilities,
power
consumption,
and
developer
requirements. 

• 
  Hardware
  structure
  • 
    FPGA:
    Highly
    configurable
    programmable
    logic
    blocks
    and
    interconnects,
    allowing
    for
    reprogrammable
    and
    custom
    digital
    circuits. 
  • 
    Microcontroller:
    Fixed
    architecture
    with
    predefined
    components
    (CPU,
    memory,
    peripherals)
    integrated
    into
    a
    single
    chip. 
• 
  Processing
  capabilities
  • 
    FPGA:
    Advanced
    parallel
    processing
    enables
    multiple
    simultaneous
    operations.
  • 
    Microcontroller:
    Designed
    for
    sequential
    processing,
    microcontrollers
    can
    only
    execute
    instructions
    one
    at
    a
    time.
• 
  Power
  consumption
  • 
    FPGA:
    Typically
    consumes
    more
    power
    than
    microcontrollers.
  • 
    Microcontroller:
    Optimized
    for
    low
    power
    consumption,
    suitable
    for
    battery-powered
    applications.
• 
  Programming
  • 
    FPGA:
    Require
    specialized
    knowledge
    in
    hardware
    description
    languages
    to
    configure
    and
    debug.
  • 
    Microcontroller:
    Can
    be
    programmed
    using
    software
    development
    languages
    including
    Javascript,
    Python,
    C,
    C++
    and
    assembly
    languages. 
• 
  Cost
  • 
    FPGA:
    Offering
    increased
    power,
    but
    requiring
    advanced
    skills,
    FPGA
    hardware
    is
    often
    more
    expensive
    with
    the
    additional
    cost
    of
    higher
    power
    consumption
    and
    specialized
    programmer
    talent. 
  • 
    Microcontroller:
    Generally,
    a
    more
    cost-effective
    solution
    with
    off-the-shelf
    availability,
    lower
    power
    consumption
    and
    support
    for
    more
    accessible
    programming
    languages.
• 
  Versatility
  • 
    FPGA:
    The
    FPGA
    is
    far
    more
    flexible
    than
    the
    microcontroller,
    allowing
    for
    customization
    on
    the
    hardware
    level.
  • 
    Microcontroller:
    While
    suitable
    for
    a
    broad
    range
    of
    applications,
    microcontrollers
    offer
    only
    superficial
    customization
    compared
    to
    FPGAs.

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