1. Embedded System Design Processtqvinh/Lectures/ESD/ESD-Ch2_2016.pdf · 1. Embedded System Design Process • Several models can be applied for embedded system design – The waterfall
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8/12/2016
Chapter 2 1
ĐẠI HỌC QUỐC GIA TP.HỒ CHÍ MINHTRƯỜNG ĐẠI HỌC BÁCH KHOA
KHOA ĐIỆN-ĐIỆN TỬ BỘ MÔN KỸ THUẬT ĐIỆN TỬ
11
Embedded System Design
Chapter 2: Develop a project of embedded system design
1. Design Process
2. Design Issues
3. Technology selection
4. Project plan
Bộ môn Kỹ Thuật Điện Tử - ĐHBK
1. Embedded System Design Process
• Several models can be applied for embedded system design– The waterfall model: in which there is a process for developing a
system in steps, where results of one step flow into the next step.
– The spiral model: in which there is a process for developing a system in steps, and throughout the various steps, feedback is obtained and incorporated back into the process.
– Consecutive refinement model
• Most followed and simple model for building an Embedded System is Waterfall model
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1. Embedded System Design Process
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Requirement definition
System specification
System partitioning
SW development
•Application SW•Compilers•Operating
Interface design
•SW driver•HW interface•User interface
HW design
•HW architecture•HW synthesis•Physical design
Integration and testing Reused components
Customers
System
architects
SW developer HW designer
CAD tools
Meet requirement?
No
YesDelivery and maintenance Chapter 2
Bộ môn Kỹ Thuật Điện Tử - ĐHBK
1.1. System Specification
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1. Product Specification
2. Engineering Specification
3. Hardware Specification
4. Software Specification
5. Test Specification
Describe how the product will be.
Describe what board, subsystem, and
firmware will be used.
Describe how the board will be
implemented and how it works.
Describe how the software will be
implemented.
Describe how the system will be tested.
Documents for System Specification
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1.1. System Specification1. Product Specification:
– What the system is to do
– What the user interface is
– What the real world I/O consists of
– What the external interface to other system is (if any)
– What are the constraints? (speed, stability, low power, cost )
• Example: Oven temperature control system
– Functions: control the heater and the fan of an oven
– I/O: temperature sensor, heater port, fan port
– User interface: LCD display, keypad
– External interface: UART
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1.1. System Specification
2. Engineering Specification:
– What kind of hardware will be used
– What are the requirements for hardware and software
• Example: Oven temperature control system
– 8051 microcontroller, LM35 sensor, LCD 16x2-B, ADC0809, RS232 IC
– Requirements• PID control algorithm
• real-time processing
• Display current temperature value
• able to set operating temperature value
• Transfer data to computer through UART
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1.1. System Specification
3. Hardware Specification:
– The requirements from engineering documents
– How the hardware implements the functionality
– The software interfaces to the hardware
• Example: Oven temperature control system
– PIC Microcontroller 12MHz, sensor LM35, LCD 16x2-B, Keypad 16, ADC0809, FET IRF260 for heater/fan control
– Microcontroller reads temperature value from LM35 through ADC, display this value to LCD, and then control heater and fan based on PID control algorithm
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1.1. System Specification
4. Software Specification:
– The requirements from engineering specification
– Interface to other software
– How the software implements the requirements
• Example: Oven temperature control system
– Temperature control algorithm
– Software functions: • void LCD_display(String str)
• int PID_control(int temp, int data[])
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1.1. System Specification
5. Test Specification:
– The device, equipment, environment for testing
– Prototype
– Testing process
• Example: Oven temperature control system
– Voltage meter, temperature meter
– Prototype: bread board
– Testing process:• calibrate temperature sensor
• check LCD, keypad
• check output port (heater, fan)
• verify PID control algorithm
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1.1. System Specification
• Group discussion
– Write a specification document for your own class project
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1.2. System partitioning• System partitioning: divide the system into three
parts:
– Hardware (HW): microcontrollers, memories, peripherals,
– Software (SW): OS, program, application software
– Interface: SW driver, HW interface, user interface
• Alternative way: divide the system into HW and SW
– which functions should be performed in hardware, and which in software?
– the more functions in software, the lower will be the product cost
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1.2. System partitioning• System partitioning examples: Oven temperature control system
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No. Functions Hardware Software
1 Measure temperature - Sensor LM35- AD converter
-ADC reading function-Calculate temperature value from the sensor input value
2 Display temperature value - LCD 1602 - LCD control function- Display function
3 Heating - Heater -Heater control function
4 Change the heating level - Button - Button reading function- Heating level setup function
5 Change heating time - Button - Timer function
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1.2. System partitioning
• Group discussion
– Apply system partitioning for your own class project
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2. Embedded System Design Issues• Design issues are problems that make
it difficult to design an embeddedsystem
1. Constraint issues
– cost may matter more than speed
– long life cycle
– Reliability/safety
– Low-power
– Size / weight
Examples: Portable heart-beat monitor– Long life cycle (10 years)
– Reliability (accuracy 99%)
– Low-power (5 using days)
– Light weight (<1kg)
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2. Embedded System Design Issues1. Constraints
Examples for smart home system
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No. Constraints Note
1 Low price (< 1.000.000 dong) Correct
2 Ability to detect smoke and fire Wrong
3 Low power (100mW when idle, 3W when active) Correct
4 Response time for control < 1ms ?
5 Support remote control by smartphones ?
6 Easy to install ?
Constraints are limitations or restrictions of some parameters of the system
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2. Embedded System Design Issues2. Functional issues
– safety-critical applications
– damage to life, health, economy
– affect to environment, society, politics
Example:
• Message LED for a shop– Display message for customers
– Malfunctions result in small damage
• Message LED for a stock market– Display stock data
– Malfunctions could damage to economy
• Battery charger– ?
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2. Embedded System Design Issues2. Functional issues
Examples for battery charger
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No. Issues Note
1 Battery can be over-heat, it need to be detected by a sensor
Correct
2 Display a charging current and battery status Wrong
3 The system must have a fuse for protection of over current
?
4 Support 3 charging modes ?
5 Apply efficient algorithm for fast charging and increase battery life cycle
?
Functional issues are problems which can affect to life, health, economy, environment, society, politics, ethics.
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2. Embedded System Design Issues3. Real-time issues
– Determine whether the system is hard/soft/non real-time
– Determine the time constraint (delay)
Example
• Door entry alarm– Non/soft real-time system: delay < 1-2s
• Video recorder– Soft real-time system: delay < 1ms
• Car airbag system– ?
• Weather temperature monitoring– ?
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2. Embedded System Design Issues4. Concurrent issues
– System and environment run concurrently
– multi-functions
– interface with other systems
– May need a scheduler to manage concurrent tasks
Examples: Weather temperature monitoring
Multi-functions:
– Read temperature values from the sensor
– Write data to memory
– Display data on LCD
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2. Embedded System Design Issues5. Reactive issues
– Continuous / discontinuous interaction
• Power on demand
– Turn ON when using
– Ex: MP3 player, Tivi system
• Always ON, once started run forever
– Continuous interaction with their environment
– Termination is a bad behavior => watchdog timer
– Ex: Camera surveillance system, data acquisition system
– Response to external periodic/non-periodic events
• Events are periodic: the system needs a scheduler to capture the events
• Events are non-periodic: the system needs to estimate miss event cases
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2. Embedded System Design Issues
• Group discussion
– Discuss about design issues of your own class project
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3. Technology Selection
• Technology
– A manner of accomplishing a task, especially using technical processes, methods, or knowledge
• Three key technologies for embedded systems
– Processor technologies: general-purpose, application-specific, single-purpose
– IC technologies: Full-custom, semi-custom, PLD
– Design technologies: Compilation/synthesis, libraries/IP, test/verification
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3. Technology Selection• Processor selection
– number of IO pins required
– interface required
– memory requirements
– number of interrupts required
– real-time considerations
– development environment
– processing speed required
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General-purpose
processor
Single-purpose
processor
Application-specific
processor
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Processor technology• “Processor” not equal to general-purpose processor
Application-specific
Registers
CustomALU
DatapathController
Program memory
Assembly code for:
total = 0for i =1 to …
Control logic and State register
Datamemory
IR PC
Single-purpose (“hardware”)
DatapathController
Controllogic
State register
Datamemory
index
total
+
IR PC
Registerfile
GeneralALU
DatapathController
Program memory
Assembly code for:
total = 0for i =1 to …
Control logic and State register
Datamemory
General-purpose (“software”)
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IC technology
• The manner in which a digital (gate-level) implementation is mapped onto an IC
– IC: Integrated circuit, or “chip”
– IC technologies differ in their customization to a design
– IC’s consist of numerous layers (perhaps 10 or more)• IC technologies differ with respect to who builds each layer and
when
source drainchannel
oxide
gate
Silicon substrate
IC package IC
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Design technology
• Compilation/synthesis:
– C Compilers: CCS C, mikro C, Keil C, Code Composer Studio,
• Libraries/IP
– Stellarisware, Tivaware, STM32 Library,
– OS: Embedded Linux, RTOS
• Test/verification
– Development kits
– Simulation tools: Proteus, Orcad, PSIM
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4. Project plan
• Build a team
• Build a plan
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Build a team
• Important points about teams
– Teams bring together complementary skills and experiences
– Teams establish communication to support real-time problem solving
– Teams develop decisions by consensus rather than by authority
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Team Contract
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TEAM CONTRACT
Team name: BK1 Date: 26 Aug. 2014
Team member Roles Signature
Nguyễn Văn A Leader, system engineer
Trần Văn B Hardware design
Nguyễn Thị C Software design
Tasks Responsible member
1. Develop system architecture Nguyễn Văn A
2. Design hardware Trần Văn B
3. Develop software Nguyễn Thị C
4. Integrate and test All
Team meeting 9AM, Wednesday, weekly
Team rules 1. Participate in all team meetings2. Listen carefully to all comments at meetings3. Complete all assigned tasks before deadlines4. Focus on results rather than excuses after.
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Build a plan
• Project planning activities
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Identify the task
Develop teams
Develop schedule
Estimate time
Plan tasks
Approve plan
Refine plan
Proceed plan
Cancel plan
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Project plan example (1)Project planning
Team name BK_DEE
Product name Home security system
Main features -Fire alarm-Door alarm-Send warning to home owner
Estimated Time 3 months (8 hours / a day)Start: 20 Aug. 2014 End: 20 Nov. 2014
Estimated Cost Components : 300,000 VNĐTools : 100,000 VNĐMaterials : 100,000 VNĐ
Total : 500,000 VNĐ
Team members Student 1: leaderStudent 2: hardware designStudent 3: software design
Schedule
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Project plan example (2)Project planning
Schedule Month 1 Month2 Month 3
1. Design system architecture
2. Design hardware part
2.1. Design central control board
2.2. Design interface
2.3. Implement hardware board
3. Develop software part
3.1. Develop control algorithm
3.2. Develop driver, user interface
3.3. Implement software program
4. Integrate and test
4.1. Simulate operations
4.2. Verify system
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Class assignment• Design a embedded system for washing machine
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No. Specification Describe
1 Product specification
-Washing process: soak, wash, rinse, spin-Mode: manual, fuzzy-Constraints
2 Engineering specification
-Inputs:-Outputs:-Use interface:
3 Hardware specification
-Microcontroller:-Sensors:-Actuators:
4 Software specification
-Functions:-Control algorithm:
5 Test specification
-Platform:-Test process:
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Group discussion
1. Consider the project car’s door mechanism
Write system specification for this project
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Group discussion
2. Consider the project car door mechanism
Write team contract and plan for the project
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