Flowcharting

1
Flowcharting
October 28, 1998 ECET2210/01
2
Purposes

• For documentation needs
• To assist understanding of structure
• Divides large tasks into small steps
• Shows how overall program works

3
Flowchart Symbols

• terminal symbol
• Used at the beginning and end of the program.
  When used at the beginning of the program, the
  word START is written inside it. Likewise, when
  it is used at the end of a program, the word STOP
  is written inside it.

4
Flowchart Symbols

• process box
• It represents some task or tasks that the program
  does or performs. It is executed regardless of
  conditions when arrived at and does not make a
  decision based on other parameters.

5
Flowchart Symbols

• Input/Output box
• Used to represent data that either enters or
  exits the microcontroller. For example, data
  entered from a keypad or switch as inputs or data
  displayed on TIL311s, LEDs, LCDs, etc.

6
Flowchart Symbols

• Decision box
• This box contains a question to be answered
  either yes or no (1 or 0)
• There are two possible exit paths marked
  appropriately yes or no. These two exits
  indicate that the program forces one action or
  the other

7
Flowchart Symbols

• On page connector
• This circle indicates that the flowchart
  continues elsewhere on the same page
• A one letter label is used inside the circle at
  both connecting points of this on page connector.
  (ie. the same label is used to connect one to
  another)

8
Flowchart Symbols

• Off page connector
• This indicates that the flowchart continues
  elsewhere on another page.
• A one letter label is used inside the label at
  both connecting points of this off page
  connector. (ie. the same label is used to connect
  one to another)

9
Flowchart Symbols

• Subroutine box
• This box is used to declare the name of a
  subroutine to be executed which is placed inside
  the box. The details of the Subroutine may be
  found on another page of the flowchart.

10
Flowchart Order
Normal flow on a flowchart is from top to bottom.
Vertical lines connect the boxes to each other.
Arrows emphasize the flow and are absolutely
necessary when altering the normal up to downward
flow. Note Flowcharts are not just used for
assembly language programming!
11
START
Initialize Ports
Receive Input
from Port One
Convert from
0-127 to 0-99
NO
Turn on Fan
YES
YES
Calculate C
NO
HEX to BCD Conversion
Is tens
YES
Blank MSD
digit 0?
NO
Output to P3
STOP
12
(No Transcript)