04-07-2013, 03:23 PM
Modeling and Specification of Embedded Systems
[attachment=56423]
Introduction
Describing embedded system’s processing
behavior
Can be extremely difficult
Complexity increasing with increasing IC capacity
Past: washing machines, small games, etc.
Hundreds of lines of code
Today: TV set-top boxes, Cell phone, etc.
Millions of lines of code
Desired behavior often not fully understood in beginning
Many implementation bugs due to description
mistakes/omissions
English (or other natural language) common
starting point
Precise description difficult to impossible
Operation of bicycles and other human-powered vehicles
A person operating a bicycle shall keep at least one hand on the handlebars at all times.
No person riding upon any bicycle shall attach the same or himself to any motor vehicle upon a roadway.
No bicycle shall be used to carry more persons at one time than the number for which it is designed or equipped.
A signal of intention to turn right or left when required shall be given continuously during not less than the last one hundred feet traveled by the bicycle before turning and shall be given while the bicycle is stopped waiting to turn. A signal by hand and arm need not be given continuously if the hand is needed in the control or operation of the bicycle.
Any person riding a bicycle shall ride in the right-hand lane. When being overtaken by another vehicle, such person shall ride as close to the right-hand side as practicable. Where a paved shoulder suitable for bicycle riding is present, persons operating bicycles shall ride on the paved shoulder. These provisions shall apply, except under any of the following situations: (a) When overtaking and passing another bicycle or vehicle proceeding in the same direction; (b) When preparing for a left turn at an intersection or into a private road or driveway; © When reasonably necessary to avoid hazardous conditions, including, but not limited to, fixed or moving objects, parked or moving vehicles, pedestrians, animals, or surface hazards.
(a) Persons operating bicycles on roadways shall ride single file; except that riding no more than two abreast is permitted in the following circumstances: (i)When riding two abreast will not impede the normal and reasonable movement of traffic; or (ii)When riding on paths or parts of roadways set aside for the exclusive use of bicycles.
State machine vs. sequential program model
Different thought process used with each model
State machine:
Encourages designer to think of all possible states and transitions among states based on all possible input conditions
Sequential program model:
Designed to transform data through series of instructions that may be iterated and conditionally executed
State machine description excels in many cases
More natural means of computing in those cases
Not due to graphical representation (state diagram)
Would still have same benefits if textual language used (i.e., state table)
Besides, sequential program model could use graphical representation (i.e., flowchart)
[attachment=56423]
Introduction
Describing embedded system’s processing
behavior
Can be extremely difficult
Complexity increasing with increasing IC capacity
Past: washing machines, small games, etc.
Hundreds of lines of code
Today: TV set-top boxes, Cell phone, etc.
Millions of lines of code
Desired behavior often not fully understood in beginning
Many implementation bugs due to description
mistakes/omissions
English (or other natural language) common
starting point
Precise description difficult to impossible
Operation of bicycles and other human-powered vehicles
A person operating a bicycle shall keep at least one hand on the handlebars at all times.
No person riding upon any bicycle shall attach the same or himself to any motor vehicle upon a roadway.
No bicycle shall be used to carry more persons at one time than the number for which it is designed or equipped.
A signal of intention to turn right or left when required shall be given continuously during not less than the last one hundred feet traveled by the bicycle before turning and shall be given while the bicycle is stopped waiting to turn. A signal by hand and arm need not be given continuously if the hand is needed in the control or operation of the bicycle.
Any person riding a bicycle shall ride in the right-hand lane. When being overtaken by another vehicle, such person shall ride as close to the right-hand side as practicable. Where a paved shoulder suitable for bicycle riding is present, persons operating bicycles shall ride on the paved shoulder. These provisions shall apply, except under any of the following situations: (a) When overtaking and passing another bicycle or vehicle proceeding in the same direction; (b) When preparing for a left turn at an intersection or into a private road or driveway; © When reasonably necessary to avoid hazardous conditions, including, but not limited to, fixed or moving objects, parked or moving vehicles, pedestrians, animals, or surface hazards.
(a) Persons operating bicycles on roadways shall ride single file; except that riding no more than two abreast is permitted in the following circumstances: (i)When riding two abreast will not impede the normal and reasonable movement of traffic; or (ii)When riding on paths or parts of roadways set aside for the exclusive use of bicycles.
State machine vs. sequential program model
Different thought process used with each model
State machine:
Encourages designer to think of all possible states and transitions among states based on all possible input conditions
Sequential program model:
Designed to transform data through series of instructions that may be iterated and conditionally executed
State machine description excels in many cases
More natural means of computing in those cases
Not due to graphical representation (state diagram)
Would still have same benefits if textual language used (i.e., state table)
Besides, sequential program model could use graphical representation (i.e., flowchart)