EE 22442 - Embedded Systems Fall 2015 Chapter One Tiny computers, hidden control EE 22442 - Embedded Systems Fall 2015 Belal H. Sababha, Ph.D. Assistant Professor of Electrical & Computer Engineering Computer Engineering Department King Abdullah II Faculty of Engineering Princess Sumaya University for Technology Amman, 11941, Jordan Phone: +962-6-535-9949 ext. 466 Email: b.sababha@psut.edu.jo Web: http://www.psut.edu.jo/sites/bsababha

What is an embedded system? A system whose principal function is not computational, but which is controlled by a computer embedded within it. Tire Pressure Sender

Embedded Systems An embedded system is a computer designed to perform a dedicated function. An embedded system performs one or a few predefined tasks, with very specific requirements. Embedded systems are often mass-produced and benefitting from economic scale. Software written for embedded systems is often called firmware.

Number System Issue Computer hardware uses binary numbers to perform all operations. To display numbers produced by the computer, both the octal and hexadecimal numbers have been used to shorten the representation. Human beings are used to decimal number system. Conversion is often needed to convert numbers between the internal (binary) and external (decimal) representations. It is common for mixed use of different number bases. A prefix is used to indicate the base of a number. Modulus Math Computers perform modulus math because it uses a limited number of bits (e.g., 8, 16, or 32 bits) to represent numbers.

Some computer essentials What is a computer? Software Hardware

Software Computer programs are known as software A program is a sequence of instructions Machine instruction : A sequence of binary digits which can be executed by the processor Hard to understand, enter, debug, and maintain for human being

Assembly language Defined by assembly instructions An assembly instruction is a mnemonic representation of a machine instruction Assembly programs must be translated into machine instructions before it can be executed -- translated by an assembler Programmers need to work on the program logic at a very low level and cannot achieve high productivity. Instruction sets the Complex Instruction Set Computer the Reduced Instruction Set Computer

High-level language Syntax of a high-level language is similar to English A translator (called compiler) is required to translate the program written in a high-level language: There are two types of compilers: native compiler and cross compiler. A cross compiler executes in one environment and generates code for another. A "native compiler" generates code for its own execution environment A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is run. Cross compiler tools are used to generate executables for embedded system or multiple platforms. It is used to compile for a platform upon which it is not feasible to do the compiling, like microcontrollers that don't support an operating system. 2. High-level languages allow the user to work on the program logic at higher level and achieve higher productivity. Source code A program written in assembly or high-level language Object code The output of an assembler or compiler

Elements of a computer

The Processor A processor consists of arithmetic logic unit (ALU), control unit, and registers. The ALU can perform many different operations. An ALU that can perform 4 operations is shown in the following Figure:

Control Unit The control unit decodes machine codes and performs the operations specified by the machine code. A machine instruction has several fields. A mandated field is the opcode field. Instruction execution is timed by a clock signal. The frequency of the clock signal used in an 8-bit or 16-bit microcontroller is from a few mega hertz to several hundred mega Hertz The control unit uses a program counter to keep track of the address of the instruction to be executed next. The fetched instruction is placed in the instruction register when is decoded, and executed. Program instructions are normally stored in sequential locations in memory. The processor may not execute instructions in sequential due to the need to execute instructions based on the condition or the need to repeat a certain group of instructions. The processor uses conditional and unconditional branch (or jump) instructions to change the program flow.

Registers A register is a storage location inside the CPU. A register is used to hold data or address during the execution of an instruction. A register, very close to the ALU, provides fast access to operands for program execution. Some processors provide a dedicated register (often called an accumulator) as one of the operands of most of the instructions. Freescale HCS12, Microchip PIC18, Intel 8051 microcontrollers use this approach. Other processors provide many general-purpose registers in the CPU that can be used as operands of instructions. Atmel AVR and AVR32, Microchip PIC24 and PIC32, Freescale Coldfire use this approach.

Microprocessor A processor implemented in a single integrated circuit (IC). The first microprocessor, Intel 4004, was introduced in 1968. The Intel 8008, the first 8-bit microprocessor from Intel, was introduced in 1972. A microprocessor requires peripheral ICs to interface with I/O devices. A microprocessor does not have peripheral functions such as timers, A/D converters, D/A converters, parallel I/O ports, and memory. The designer need to add peripheral ICs and memory devices to the microprocessor in order to build a product. + High Performance + Choice of Peripherals and Memory Configurations - Expensive - Power Consumption (Heat) - Size

Microcontroller Vs. Microprocessor A microcontroller incorporates the processor and one or more of the following peripheral functions and memory in one very large scale integrated circuit (VLSI): Memory Timer functions Serial communication interface such as UART, I2C, SPI, CAN, and Ethernet A/D converter D/A converter Direct memory access Parallel I/O ports Memory component interface Software debug support Microcontroller

Dimming a Light using a microprocessor

Dimming a light using a microcontroller

Memory Technologies & Types Magnetic Memory Magnetic drums, magnetic tapes, and magnetic disks are the three major magnetic memory devices that have been invented. Only magnetic disks are still being widely used today Hard disks are rarely used in an embedded system Optical Memory Compact disk (CD) and digital video disc (DVD) are two major optical memory devices. CD was introduced in 1982. CD has two versions: CD-R and CD-RW. The capacity of a 12-inch CD is 700 MB. A 12-inch DVD has the capacity of 4.7 GB DVD has two versions: DVD-R and DVD-RW versions. Semiconductor Memory Semiconductor memory can be classified on the basis of volatility and read-writability. On the basis of volatility, semiconductor memory is divided into volatile and non-volatile memory. On the basis of read-writability, semiconductor memory is divided into random-access memory (RAM) and read-only memory (ROM). RAM: DRAM, SRAM, MRAM, FRAM, ROM: MROM, PROM, EPROM, EEPROM, Flash Memory

Organizing memory

Inside Microcontrollers

Microcontroller families

Microcontroller packaging and appearance

Microchip and the PIC microcontroller Background : General Instruments, Peripheral Interface Controller ,PIC 1650 and 1655 late 1970s, RISC, 30 instructions, Microchip, 8-bit PIC 8-bit microcontrollers today Characteristics that all have in common. Lowcost, Self-contained, Pipelined, RISC, Harvard structure, Single accumulator (the Working, or W, register), Fixed reset vector.

Comparison of 8-bit PIC families 10, 12, 16, 18 : series C: CMOS F: Flash A: Technology Upgrade

An introduction to PIC microcontrollers using the Baseline Series

The architecture of the 12F508