Embedded Systems Structure pdf

Amr Ali Abdel- Naby@2010Embedded Systems Structure Embedded Systems Structure Amr Ali Abdel-Naby Embedded Systems Developer amraldo@hotmail.com +2-012-3600-207 Amr Ali Abdel-Naby@2010 Embedded Systems Structure Outline • Composition of Embedded Systems • Processor • System Bus • Memory Devices • Peripherals Amr Ali Abdel-Naby@2010 Embedded Systems Structure Part I: Embedded Systems Structure • Composition of Embedded Systems • Processor • System Bus • Memory Devices • Peripherals Amr Ali Abdel-Naby@2010 Embedded Systems Structure What is an Embedded System? • A system composed of HW + SW to perform a dedicated function. • On average, a human being meets 100s of embedded systems daily Amr Ali Abdel-Naby@2010 Embedded Systems Structure Embedded System Components Processor Memory Devices I/O Devices Application SW Operating System Device Drivers H W SW Amr Ali Abdel-Naby@2010 Embedded Systems Structure Part I: Embedded Systems Structure • Composition of Embedded Systems • Processor • System Bus • Memory Devices • Peripherals Amr Ali Abdel-Naby@2010 Embedded Systems Structure The Processor • The core of a digital system • AKA CPU • Performs arithmetic, control, data, and I/O operations • A small IC that embeds everything a CPU needs is called a microprocessor. • Nowadays, this IC is called a SOC Amr Ali Abdel-Naby@2010 Embedded Systems Structure The Processor Structure • Registers • ALU: Arithmetic Logic Unit • CU: Control Unit • Internal Bus CU ALU Registers Internal Bus Amr Ali Abdel-Naby@2010 Embedded Systems Structure Registers • Temporal storage inside the CPU o Flip-flops + latches • General purpose register o Carry out program or data processing • Control register o Controls the program or the processor o Program Counter (PC), … • Status/flag register o Shows the current state of the processor Amr Ali Abdel-Naby@2010 Embedded Systems Structure ALU • Arithmetic operations o +, -, … • Logical operators o AND, OR, … • Writes operation results to the status register or the flag register o Carry occurrence, overflow occurrence, … [...]... performance Embedded Systems Structure Part I: Embedded Systems Structure • • • • • Composition of Embedded Systems Processor System Bus Memory Devices Peripherals Amr Ali Abdel-Naby@2010 Embedded Systems Structure System Bus Architectures • Von-Neumann CPU • Harvard CPU Instruction/Data Memory Instruction Memory Data Memory Amr Ali Abdel-Naby@2010 Embedded Systems Structure Part I: Embedded Systems Structure. .. physical address • Memory protection CPU Virtual Address Amr Ali Abdel-Naby@2010 MMU Physical Address Embedded Systems Structure Main Memory Part I: Embedded Systems Structure • • • • • Composition of Embedded Systems Processor System Bus Memory Devices Peripherals Amr Ali Abdel-Naby@2010 Embedded Systems Structure I/O Device • Exchanges information with CPU • Includes digital and non-digital signals •... readability Amr Ali Abdel-Naby@2010 Embedded Systems Structure C/Cs of Assembly Language • Pros Better readability and understanding compared to machine code o Easier to debug and maintain compared to machine code o • Cons Knowledge of processor internal structure and HW is necessary o Different assembly for different processors o Amr Ali Abdel-Naby@2010 Embedded Systems Structure Assembler and Assemble... Abdel-Naby@2010 Device Signals I/O Controller Embedded Systems Structure I/O Device I/O Device Address Allocation • Allocation is necessary to control each I/O device • I/O mapped I/O o o Exclusive I/O address space Widely used in PC world • Memory mapped I/O o o Uses unused regions of normal memory addresses Widely used in embedded world Amr Ali Abdel-Naby@2010 Embedded Systems Structure I/O Resource Management... machine code Amr Ali Abdel-Naby@2010 Embedded Systems Structure Instruction • Instruction = Op Code + Operand o o Op Code is an action taken by a processor Operand is the target the Op Code should take action to ADD A,B,C Op Code: ADD Operands: A, B, C Symantec: Add register B and register C and put result in register A Amr Ali Abdel-Naby@2010 Embedded Systems Structure Types of Processors • Complex... Execute 2 Fetch 3 Amr Ali Abdel-Naby@2010 Execute 2 Execute 3 Embedded Systems Structure Fetch 3 Execute 3 Various Processors • i386 o o Long history PCs • ARM o o Simple Cell phones and PDAs • PowerPC o Networking capabilities • M68K o Network devices and portable terminals • MIPS o High speed network devices Amr Ali Abdel-Naby@2010 Embedded Systems Structure MCU, MPU, and SoC • System on Chip (SoC) o o... Abdel-Naby@2010 Embedded Systems Structure Cache Memory System CPU 400 MHZ Main Memory 10 MHZ CPU + Cache 400 MHZ BUS 66 MHZ BUS 66 MHZ System performance is lowered due to slow bus and memory regardless of high speed CPU Amr Ali Abdel-Naby@2010 Main Memory 10 MHZ Improved performance by accompanying CPU with a high speed memory to store frequently accessed instructions/data Embedded Systems Structure Read... complete line o Amr Ali Abdel-Naby@2010 Embedded Systems Structure Write Operation with a Cache • Write Through o A CPU write to a specific address writes to both the external memory and the cache • Write Back o A CPU write to a specific address writes only to the cache and postpones the writing to external memory at a later time Amr Ali Abdel-Naby@2010 Embedded Systems Structure Memory Management Unit •... integrated on a single chip  SW + HW • MCU, MPU o Another naming of an SoC  Depends on vendor Amr Ali Abdel-Naby@2010 Embedded Systems Structure Program • A list of acceptable processor instructions • Designed to achieve a specific result Amr Ali Abdel-Naby@2010 Embedded Systems Structure Machine Code and Assembly Language • Machine code o o o 1’s and 0’s only Understood by processor only Inconvenient... Abdel-Naby@2010 Embedded Systems Structure Instruction Processor Bus • A bus is a path that connects the various devices of a system • Internal bus o Between registers and ALU • External bus o o o o Between I/O devices, memories, and CPU Data bus: transfers data Address bus: transfers address information Control bus: transfers control signals Amr Ali Abdel-Naby@2010 Embedded Systems Structure Pipeline . Abdel- Naby@201 0Embedded Systems Structure Embedded Systems Structure Amr Ali Abdel-Naby Embedded Systems Developer amraldo@hotmail.com +2-012-3600-207 Amr Ali Abdel-Naby@2010 Embedded Systems Structure Outline • Composition. of Embedded Systems • Processor • System Bus • Memory Devices • Peripherals Amr Ali Abdel-Naby@2010 Embedded Systems Structure Part I: Embedded Systems Structure • Composition of Embedded Systems • Processor • System. Structure Part I: Embedded Systems Structure • Composition of Embedded Systems • Processor • System Bus • Memory Devices • Peripherals Amr Ali Abdel-Naby@2010 Embedded Systems Structure The Processor • The