Embedded software enggineering: Advanced harware fundamentals

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Getting to know the hardware, understanding the big picture, draw your own data flow diagram, examine the landscape,... As the main contents of the lecture "Embedded software engineering: Advanced hardware fundamentals ". Each of your content and references for additional lectures will serve the needs of learning and research.

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Nội dung Text: Embedded software enggineering: Advanced harware fundamentals

Embedded Software Engineering Advanced Hardware Fundamentals Graduate Course ESE Lecturers: Dr. Nguyen Ngoc Binh Dr. Le Quang Minh
Getting to Know the Hardware • How to familiarize with a new board? • How to create a header file with the board’s important features? • How to write software code to initialize a newboard? ESE 2
Understanding the Big Picture • Understand the general operation of the system first • Read all documentations • Before picking up the board should answer: • What is the overall purpose of the board? • How does data flow through it? ESE 3
Draw your own dataflow diagram ESE 4
Examine the landscape • Put yourself in the processor’s SHOES! • What does the processor’s world look like? • The processor has a lot of compatriots! – Memories: Storage and retrieval of data / code – Peripherals: Coordinate interaction with outside world (I/O), or specific hardware func • Examples: serial ports, timers • Address Spaces (Address Book of processor) – Memory Space – I/O Space ESE 5
Memory Map for Arcom Board ESE 6
Header File • Describes most important features of a board • Abstract interface to hardware • Refer to devices by name, instead of addresses – Makes software more portable • If 128 KB RAM is moved, – just change header file only, and – recompile program (no need to change program code) ESE 7
Header File: Memory Map ESE 8
Pointers v/s Address • C/C++ compilers for 80x86 use 32-bit pointers • Intel’s 80188EB processor: – 20-bit address space – 16-bit internal registers • TWO 16-bit registers are required: – a segment register (base address) – an offset register (offset address) • Physical Address 12345h: ESE 9
I/O Map Repeat the memory map exercise to create an I/O map! ESE 10
How to Communicate? • Two basic communication techniques: – polling – interrupts • Processor issues some commands to device • Processor waits for device to complete action • Timer: 1000  0 (countdown) ESE 11
Polling: “are we there yet?” do { // Play games, read, listen to music, etc. … // Poll to see if we’re there yet. status = areWeThereYet(); } while (status == NO); ESE 12
Interrupts Asynchronous signal from peripheral to CPU • Processor issues commands • Processor does other things • Device interrupts processor • Processor suspends its work • Processor executes interrupt service routine (ISR) • Processor returns to the interrupted work ESE 13
Interrupts • Not all automatic! • Programmer must: – write ISR – install ISR – enable its execution when interrupt occurs • Initially, a significant challenge!!! • Code is better structured! • Overhead: save registers in memory, disable lower-priority interrupts, transfer control, etc. ESE 14
Interrupt Map • Each processor has a few interrupts • Each interrupt has: – an interrupt pin on CPU – an ISR • Must map interrupt pin with ISR • Interrupt Vector Table – Array of pointers to functions, – Located at some known memory address ESE 15
Interrupt Map for Arcom Board ESE 16
Interrupt Map: Header File ESE 17
Get to Know the Processor • Read databooks of processors! • Three types of processors: – Microprocessors: powerful, general-purpose, Eg: Motorola’s 68k, Intel’s 80x86 – Microcontrollers: less powerful, systemspecific, Eg: 8051, Motorola’s 68HCxx, Intel’s 386EX – Digital Signal Processors (DSP): fast calculations of discrete-time signals, Eg: TI’s TMS320Cxx, Motorola’s 5600x ESE 18
Intel’s 80188EB Processor • Microcontroller version of 80186 • On-chip peripherals: – Interrupt control unit – 2 programmable I/O ports – 3 timer/counters – 2 serial ports – DRAM controller – Chip-select unit • 80188 controls them via internal buses ESE 19
Peripheral Control Block (PCB) • Located in I/O space at address FF00h • Control and status registers for each on-chip peripheral are located at fixed offsets from the PCB base address • Include those offsets in your HEADER file ESE 20