 Applications of PICs
 Advantages/disadvantages
 Digital and analogue control
 Loops, sub-routines, scanning, counting and feedback
 Interrupts
 Problems with interfacing to external devices
 Structure of microprocessors
 Applications of microprocessors in manufacturing
 Programmable Integrated Circuit/Programmable Interface






Controller
Capable of storing instructions in the form of a programme
Can switch output devices on and off in sequence in
response to input signals
Can be programmed and erased up to 100,000 times
Require a supply voltage of 3 to 5.5V
Available as 8, 14, 18, 28 and 40 pin DIL packages
Applications include alarm systems, medical equipment,
vending machines, traffic lights, cash machines, petrol
pumps…..
Advantages
 One PIC can replace a
wide variety of separate
electronic components
or circuits
Advantages
 One PIC can replace a
wide variety of separate
electronic components
or circuits
 Increase d product
reliability through the
use of less components
Advantages
 One PIC can replace a
wide variety of separate
electronic components
or circuits
 Increase d product
reliability through the
use of less components
 Reduced stock levels
Advantages
 One PIC can replace a wide
variety of separate
electronic components or
circuits
 Increase d product
reliability through the use
of less components
 Reduced stock levels
 Simplified product
assembly and smaller end
products
Advantages
 One PIC can replace a wide




variety of separate electronic
components or circuits
Increase d product reliability
through the use of less
components
Reduced stock levels
Simplified product assembly
and smaller end products
Greater product flexibility,
adaptability resulting in rapid
product changes
Advantages
 One PIC can replace a wide




variety of separate electronic
components or circuits
Increase d product reliability
through the use of less
components
Reduced stock levels
Simplified product assembly
and smaller end products
Greater product flexibility,
adaptability resulting in rapid
product changes
Disadvantages
Advantages
Disadvantages
 One PIC can replace a wide
 Knowledge of programming




variety of separate electronic
components or circuits
Increase d product reliability
through the use of less
components
Reduced stock levels
Simplified product assembly
and smaller end products
Greater product flexibility,
adaptability resulting in rapid
product changes
required
Advantages
Disadvantages
 One PIC can replace a wide
 Knowledge of programming




variety of separate electronic
components or circuits
Increase d product reliability
through the use of less
components
Reduced stock levels
Simplified product assembly
and smaller end products
Greater product flexibility,
adaptability resulting in rapid
product changes
required
 PICs have a low power output
and so require interfacing
circuitry to drive higher
current devices
For traditional electronics
this would require a variety
of components designed
through a circuit diagram
Microcontroller
diagrams
System diagrams can
still be used to
develop designs, but
INPUT
PROCESS
OUTPUT
the process element
would be replaced
with lines of
programme rather
INPUT
PIC
MICROCONTROLLER
OUTPUT
than a list of
components
Although still requiring a
circuit, processing would be
programmed with all previous
components being replaced by
a single PIC
Inside a PIC
Like all computers, a
PIC micro controller
CPU
has a Central
Processing Unit,
Random Access
Memory, Read Only
RAM
Memory, a clock and
IO
Input/Output ports.
The key difference is
that all of these are
ROM
built into one IC,
rather than a variety
of individual ICs
FLASH
One Time
Programmable (OTP)
 Most common form
 Can be programmed
 Can be erased up to
only once
 More suited to mass
produced products
100,000 times
 Reprogrammed by
simply downloading the
new programme to the
IC
 Offer flexibility to
manufactures
Terminator
Subroutine
Decision
Input/Output
Process
Programming can be via a flow chart
sequence or BASIC programming
language
Intel Museum - How Microprocessors Work
#1
How Do Microprocessors Work??