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What are the advantages of 'digital' computers compared to analog ones?
What are the main components of a digital computer?
Memory, Datapath, Control unit, Input/Output
Embedded systems are reconfigurable.
False
DSP stands for Digital __________ Processor.
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What are the fundamental parameters in the comparison between microcontrollers and DSP?
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Which characteristics determine the level of performance required for a microprocessor?
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Microcontrollers and DSPs have an operating system that manages multiple concurrent processes.
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The computation time can be estimated by the equation ߔ = ߔ௫ଵ/߇
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Which method can be used to increase the speed of a processor?
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What is a key characteristic of a DSP in terms of power consumption?
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What is a common use of DSPs in the creation of algorithms?
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What is a key feature of a DSP that allows for efficient management of peripherals?
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What is the primary difference between a DSP and a microcontroller?
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What is the term used to describe real-time control processors?
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What is a factor that affects the cost of electronic devices?
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What is a characteristic of recent DSPs?
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What is an important factor to consider when comparing the cost of DSPs and microcontrollers?
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What is a characteristic of microcontrollers?
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What is the main difference between analog and digital devices?
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What is a characteristic of embedded systems?
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What is an example of a digital device?
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What is a characteristic of DSP?
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What is a characteristic of microcomputer/microcontroller?
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What is the primary function of the datapath unit in a digital computer?
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What is the role of the control unit in the operation flow of a digital computer?
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What type of interface is provided by the Input/Output unit in a digital computer?
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What is the Central Processing Unit (CPU) composed of?
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What is stored in the memory of a digital computer?
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What is the advantage of digital computers in terms of noise robustness?
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What is the role of the processor bus in a computer architecture?
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What is the limitation of the question 'Is the Personal Computer the only digital computer?'?
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What is the top-down approach in microcontrollers based on?
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What is the main benefit of using abstraction layers in microcontrollers?
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What is the process of dividing a complex system into smaller subsystems called?
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What translates instructions into processor commands?
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What is the purpose of the set of instructions and registers available to the processor?
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What is the result of decomposing complex systems into simpler subsystems?
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What is the ultimate goal of the top-down approach?
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What is the relationship between abstraction layers and the complexity of a system?
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What is the primary factor that determines the cost of developing an application?
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What is the key parameter in applications involving signal-processing and/or real-time control activities?
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How can the speed of a processor be increased?
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What is the limitation of reducing the processor clock period?
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What is the purpose of benchmarking in evaluating processor performance?
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What is the characteristic of a good DSP benchmark program?
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What is the limitation of using MIPS as a performance index?
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What is the difference between DMIPS and MIPS?
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What is the primary advantage of using kernel benchmarking for DSPs?
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Why is the computation time required by a program dependent on the processor architecture?
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Study Notes
Digital Systems Basics
- A digital computer is preferred over an analog computer due to its advantages:
- Noise robustness
- Degradation robustness
- Reconfigurability
The Digital Computer
- A digital computer consists of:
- Memory: stores programs, inputs and outputs, and intermediate values
- Datapath: performs arithmetic operations and data processing
- Control unit: supervises the flow of information between units
- Input/Output: digital-to-analog interface for input devices (e.g., keyboard, mouse) and output devices (e.g., screen, printer)
Operation Flow
- The control unit retrieves the next instruction from memory
- It asks memory and inputs for needed parameters
- It asks the datapath to perform the necessary operations
- It moves the results to memory and output devices
Computer Architecture
- A computer architecture consists of:
- Separate control unit and datapath
- Connections between units (e.g., processor bus, input/output bus)
- Other parts include:
- External cache
- Random access memory
- Input/output devices (e.g., keyboard, LCD)
Embedded Systems
- Embedded systems are small, less powerful computers used in devices such as:
- Microcontrollers
- Digital signal processors (DSPs)
- They are not reconfigurable and have:
- Limited or no human interface devices
- No mass storage
Abstraction Layers
- Abstraction layers are used to simplify complex systems by:
- Decomposing the system into subsystems
- Breaking down the subsystems into smaller components
- Connecting the simple parts to form the complete system
- This approach has advantages, including:
- Easy to update
- Easy to improve upper layers
Microcontrollers and DSP
- A microcontroller is a microprocessor optimized for carrying out control, timing, and supervision tasks
- It has on-chip memory and peripherals, and is used in various applications, including:
- Home appliances
- Mobile phones
- Industrial automation
- A digital signal processor (DSP) is a microprocessor optimized for real-time digital signal processing
- It has high computing power and is used in applications such as:
- Audio and video signal processing
- Data compression and encryption
DSP vs µC
- Microcontrollers (µC) were traditionally used for control functions, while digital signal processors (DSPs) were used for signal processing functions
- However, the distinction between the two is becoming less clear, as modern DSPs often incorporate peripherals typical of µCs, and some µCs have computing powers similar to those of DSPs
- The choice between the two ultimately depends on cost and performance considerations### Microcontrollers Basics
Effective Support
- Effective support from the manufacturer of the device used is crucial, including:
- Function libraries
- Drivers
- Technical support
- Support forums
Performance Comparison
- Fundamental parameters in comparing microcontrollers and DSPs are:
- Cost
- Performance
- Performance is determined by:
- Needed peripherals and their specifications (e.g. 8, 10, or 12-bit A/D converter)
- Operating conditions (e.g. maximum permissible power consumption, temperature)
- Computing power required (e.g. real-time control, signal processing)
Computation Time
- Computation time is a key parameter in applications involving signal-processing and/or real-time control activities
- Estimating computation time requires:
- Processor clock period
- Number of cycles required by the most commonly used instructions in the program
- Number of instructions (for each type) required by the program
- The clock period and number of cycles required by the instructions can be obtained from the processor datasheet
- The number of instructions required by a program depends on the architecture (ISA) of the processor
Computation Time Estimate
- The computation time can be estimated using the equation:
- T = ∑ (n_i * c_i) / f
- Where T is the computation time, n_i is the number of instructions of class i, c_i is the average number of cycles for an instruction of class i, and f is the processor clock frequency
- Under the hypothesis that the program is not interrupted by other programs and memory-related delays are not taken into account
Increasing Speed
- It is possible to increase the speed by:
- Reducing the processor clock period
- Reducing the total number of instructions
- Reducing the number of cycles needed by the instructions
- Reducing the processor clock period:
- Causes an increase in power dissipated by the processor
- Can be limited by reducing the supply voltage
- Demands processors with low supply voltages (< 1 V)
- Reducing the total number of instructions:
- Depends on the architecture
- Leads towards architectures with complex instructions (CISC) compared to architectures with simpler and fewer instructions (RISC)
- Reducing the number of cycles needed by the instructions:
- Requires more complex hardware/circuit organization
- Can be achieved through wired control instead of micro-programmed control
- Reduces the duration of the operation through greater parallelism and pipeline use
Performance Comparison
- Performance evaluation of general-purpose processors uses benchmarking (sample programs)
- Benchmarking is also applied to DSPs, but with specific algorithms for signal-processing applications (e.g. FFT, FIR filters, IIR)
- Processor benchmarking is inapplicable to DSPs because it evaluates the compiler-processor together rather than the processor alone
- For DSPs, kernel benchmarking is used instead
DSP Benchmarking
- Characteristics of a good DSP benchmark program:
- Relevance: it must be a typical application of a DSP
- Ease of unambiguous definition: it must be clear which specific algorithm for implementing an operation it uses
- Simplicity
- Optimizability: it must be able to be optimized for each DSP under test
Performance Indices
- Common performance indices:
- MIPS: millions of instructions per second
- DMIPS: millions of instructions per second for a specific benchmark algorithm (Dhrystone)
- FLOPS: millions of floating-point operations per second
- These indices are highly unreliable and do not allow comparisons between devices from different families
- MIPS:
- Maximum number of instructions that a CPU can perform in a unit of time
- The number of instructions required by a certain algorithm depends on the CPU architecture (and the quality of the compiler)
- DMIPS:
- Number of instructions that a processor can execute per unit of time during the execution of a specific algorithm (Dhrystone benchmark)
- Conceived in 1984 to compare the performance of general-purpose processors
- Sometimes normalized to the clock frequency, expressing the speed in DMIPS/MHz
- FLOPS:
- Maximum number of floating-point operations per unit of time
- Applicable only to processors with floating-point arithmetic
- None of the indices mentioned consider essential aspects for the performance of a CPU, such as memory access speed and quality of instructions.
Digital Computer Basics
- A digital computer can be defined as a machine that can perform operations using 0s and 1s.
- "Digital" advantages include: • Noise robustness • Degradation robustness • Reconfigurable
Digital Computer Components
- Memory stores: • Programs (list of commands) • Inputs and outputs • Intermediate values
- Datapath performs: • Arithmetic operations • Data processing
- Control unit supervises: • Information flow between units
- Input/Output (I/O) is a digital-analog interface, comprising: • Input devices (keyboard, mouse, scanner, touch) • Output devices (screen, printer, LED, sound) • Mixed devices (drives, ETH, WiFi)
Operation Flow
- Control unit retrieves the next instruction from memory
- Control unit asks memory and inputs for needed parameters
- Control unit asks datapath to perform operations
- Control unit moves results to memory and outputs
Computer Architecture
- Separate control unit and datapath
- Connections include: • Processor bus • Input/output bus • Bus interface (communications between parts)
- Other parts include: • External cache • Random access memory (RAM)
Embedded Systems
- Microcomputer/microcontroller: smaller, less powerful computers
- DSP (Digital Signal Processor): special-purpose computers for signal processing
- Embedded systems are not reconfigurable, with limited or no Human Interface Devices (HID)
- Embedded systems have no mass storage
Analog and Digital Systems
- Analog systems include: • Thermistor • Sensors • Knob • Loudspeaker • Lighting • Motor • Dial • WiFi
- Digital systems include: • Button • Keypad • Switch • LED • Lighting • Motor • Control • Relays
Abstraction Layers
- Top-down approach: • Divide and conquer • Start with a complex system and decompose it into subsystems • Connect the simple parts
Microcontrollers and DSP
- A microcontroller is a small computer on a single integrated circuit (IC)
- A DSP is a microprocessor optimized for digital signal processing
- DSPs have: • High computing power • Low cost • Low power consumption
- DSPs are used in: • Audio and video encoding/decoding • Data compression/decompression • Data encryption/decryption • Audio and video mixing • Sound synthesis
DSP vs Microcontroller
- The main difference between DSPs and microcontrollers is: • Computing power • Cost • Performance
- Microcontrollers are used for control functions, while DSPs are used for signal processing
- The distinction between DSPs and microcontrollers is becoming less clear
Computation Time
- Computation time is a key parameter in applications involving signal processing and/or real-time control
- Computation time can be estimated using: • Processor clock period • Number of cycles required by instructions • Number of instructions required by the program
- Computation time can be increased by: • Reducing the processor clock period • Reducing the number of instructions • Reducing the number of cycles required by instructions
Performance Comparison
- Benchmarking: evaluating the performance of a processor using sample programs
- Performance indices: • MIPS (millions of instructions per second) • DMIPS (millions of instructions per second for a specific benchmark algorithm) • FLOPS (millions of floating-point operations per second)
- These indices are unreliable and do not allow comparisons between devices from different families
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Description
Test your knowledge of digital systems, including advantages of digital computers and components of a digital computer.
