Embedded Systems Lesson 4 (Embedded Processors) PDF

Embedded Systems Lesson 4 2. I/O ports (Embedded Processors) 3. RAM: contains temporary data INTRODUCTION 4. ROM: contains program and...

Embedded Systems Lesson 4 2. I/O ports (Embedded Processors) 3. RAM: contains temporary data INTRODUCTION 4. ROM: contains program and constant data – the firmware, use Basic characteristics of an embedded Flash memory instead of true system: ROM to hold the firmware o system built to perform its duty, 5. Timers completely or partially independent of human 6. Serial interface: often a USART intervention 7. EEPROM: contains “permanent” o designed to perform a few tasks data in the most efficient way 8. Analog-to-digital converter o interacts with physical elements 9. Digital to analog converter in our environment o an embedded system is designed to be more compact, energy PROCESSORS efficient, and inexpensive first microprocessor was developed by o exhibit single tasking and INTEL Corporation in 1971 in the brand multitasking capabilities name of INTEL 4004 o contain processing cores that are o 4-bit microprocessor designed typically either microcontrollers or with large scale integration (LSI) digital signal processors (DSP) technology being dedicated to handle a particular o number of instructions of INTEL task 4004 was 45 can be optimize it to reduce the size and o fabricated by P-MOS technology cost and increase the reliability and performance o rate of execution 50 KIPS (Kilo instruction per second) range from portable devices to large stationary installations other 4-bit microprocessors complexity varies from low, with a single o PPS- 4 by Rockwell international microcontroller chip, to very high with o T 3472 by Toshiba multiple units, peripherals and networks o TMS-1000 by Texas instruments more and more of the stuff that was once “peripheral logic” has been integrated on the same chip as the CPU 1972 INTEL produced the first 8-bit microprocessor INTEL 8008 Important parts of an embedded o address an expanded memory processor are mentioned below size of 16 Kilobytes and 48 instructions 1. CPU  1973 INTEL-Corporation produced RISC microprocessors available in the INTEL 8080 market o fabricated by NMOS technology o PowerPC 601.603, 604 etc. o ten times faster than 8008 o Intel’s PA8000 microprocessor (500 KIPS) o DEC’s Alpha21064 o memory capacity of INTEL 8080 o SUN’s SPARC etc. is 64 KB CISC microprocessors In 1975 INTEL produced INTEL 8085 o Intel’s 486, Pentium o execution rate is 769.23KIPS o Pentium Pro o own internal clock generator and internal system controller o Pentium II o can execute 246 instructions o Celeron 1978 when INTEL introduced a 16-bit o Pentium III microprocessor INTEL 8086 after one year, INTEL Corporation released 8088 o Pentium IV o can address one Megabyte of o Motorola 68000 etc. memory location Intel introduced 80186 microprocessors o execution speed of 8086 o not at all popular for general microprocessor is 2.5 million purpose computers instructions per second (MIPs) o used for only industrial control o popular to use in microcomputer applications Intel produced microprocessor 80286 o speed of execution increased by o 24-line address bus, can provide using instruction queue or cache address for 16 MB memory o number of instructions of this o clock speed is 8 MHz microprocessor is about 20,000, o execution rate 4 MIPS known as complex instruction set computers (CISC) 1986 INTEL Corporation introduced 32 bits processor 80386 o have more internal registers o 32-bit data bus and 32 bit o 16-bit registers help to write memory address bus program efficiently o memory capacity of this CISC microprocessor causes reduction processor is 4 GB (Gigabyte) in computing speed of microprocessors o suitable for graphic user interface reduced instruction set computer (RISC) (GUI) and Computer Aided microprocessor is developed to increase Design (CAD) computing speed using hardwired control unit o includes hardware circuitry for memory management assignment  1989 INTEL Corporation introduced o three integer units and one 80486 microprocessors floating point unit o incorporates 80386 like o clock frequency of Pentium pro- microprocessor, 80387 like microprocessor is 166 MHz numeric coprocessor and 8 KB o 64-bit data bus cache memory in the same integrated circuit package o 64GB main memory o clock speed of 50 MHz to 66 MHz o 16 KBL1 cache and 256 KB L2 cache employs three execution o instruction execution rate is 50 engines MIPS o 36-bit address bus for 64 GB o expandable16 KB cache memory memory system o tripled clock version increases the speed 120 MH Embedded Systems Lesson 5 o has 32-line address bus (Embedded Processors) 1993 INTEL Corporation introduced 64- bit Pentium (P5) microprocessor using General Purpose Processors super scalar technology designed to solve problems in a large o execution rate of this processor is variety of applications 110 MIPS manufacturer can invest more for o clock frequency is100MHz improving the design with advanced features o Double clocked version of Pentium processor design tools are provided by the manufacturer in such processors o operates at 133 MHz microprocessor is a clock driven o cache memory of this processor semiconductor device is increased to 16 KB Microprocessors consists of following three o 64-bit data bus building blocks: o memory size of Pentium 1. Arithmetic and Logic Unit (ALU): processor is 4 GB o constructed with logic gates o executes two instructions simultaneously per clock period o used for mathematical computation and logical decision o JUMP prediction technology is included 2. Register Array: o includes internal floating-point o consist of memory elements coprocessor in the same fabricated in microprocessor. integrated circuit package o microprocessors are named Pentium pro-microprocessor (P6) was according to its register size also introduced by INTEL o store data temporarily during o contains 21 million transistors execution of the program  o program counter (PC), holds the 4. Direct memory access (DMA) control address of the next program unit instruction 5. Memory o Instruction registers (IR) to hold 6. CPU the fetched instruction 7. Timer unit. 3. Control Unit (CU): o provides control signal to different segments of microprocessor Characteristics of Embedded Microprocessors o controls the timing of operation of electronic circuits of does not require any human interaction, microprocessor. no need of human supervisor o consists of circuitry for retrieving relies on the stored programs and data program instructions and moving being sent to control its behavior data through the data-path according to those instructions interact with their environments through an interrupt system interrupts are signals sent from devices Embedded Microprocessor that let the processor know that they need to use the processor VLSI chips that are incorporated into products processor then enters its interrupt program and decodes the source to take microprocessors that are used in the correct action electronic devices programs are stored in memory designed to perform a certain task and the user seldom has to interact with it does not possess a large amounts of available memory Two areas of embedded control applications: programs run by embedded microprocessors are usually short 1. Event control or real-time control use a variety of other devices which are 2. Data control built onto the chip as well microcontrollers are used for event control or real-time control they sometimes need to accept input embedded microprocessors are used for from the device through the analog to data control digital converter Embedded controllers require following analog to digital converter is used to building blocks: convert incoming analog signal into data 1. Data processing unit form that the processor can recognize 2. Data formatting unit digital to analog converter allows the processor to send signal to the device it 3. I/O control unit is controlling  most common types of timers is the ARCHITECTURE OF INTEL 80186/80188 Programmable Interval Timer (PIT) MICROPROCESSORS counts down from some prefixed value Difference between 80186 and 80188: to zero, sends an interrupt to the processor 1. 80186 microprocessors have 16-bit data bus, while 80188 contains an 8-bit data useful to restart the device to be bus controlled 2. 80186 microprocessors have 6-byte pre- time processing unit (TPU), a timer, fetch queue but Intel 80188 more sophisticated in performance microprocessor has 4 byte queue. can detect input events and generate output events Embedded Microprocessor Systems main function is to monitor and control some real-world event Steps to design an embedded microprocessor system: 1. Product requirement definitions 2. Functionality description 3. Processor selection 4. Hardware design 5. Firmware design. 6. Integration steps are not necessarily serial building hardware, writing code, and both contain additional reserved debugging the system are necessary interrupt vectors and some powerful built state transition diagrams in addition to in I/O features flow charts for design consideration are preferred Special features: state and dataflow diagrams are to be made 1. DMA controller unit debugging hardware and software is o transfers data between I/O and important to consider so that debug memory facilities can easily be added 2. three programmable timers o 16-bit timer/counters  o 2 of the timers are used for Embedded Systems Lesson 6 following purposes (Embedded Processors) ▪ Counting external events MICROCONTROLLER ▪ provide waveforms from a highly integrated chip that contains a either an external clock or CPU, ROM/EPROM, RAM and I/O ports a CPU clock designed for a very specific task to ▪ interrupt CPU after control a particular system specified number of events parts can be simplified and reduced, o third timer counts CPU clock cuts down on costs cycles sometimes called embedded o can also be used to interrupt CPU microcontrollers after selected clock cycle has a CPU in addition to a fixed amount o provides a DMA request pulse to of RAM, ROM, I/O ports, and a timer all the DMA unit on a single chip 3. Programmable interrupt controller used to read data, perform limited o provides interrupt requests calculations on that data, and control the between internal and external devices based on those calculations sources Special Characteristics of Microcontrollers: o interrupt, method of creating a 1. embedded inside a device so that they temporary halt during program can control its actions execution 2. dedicated to one task and run a specific ▪ allows peripheral devices program which is stored in the ROM to access the microprocessor 3. low-power devices ▪ microprocessor responds 4. has a dedicated input device and often ISR (Interrupt Service has a small LED or LCD display for Routine), a short program output, takes input and controls the to instruct the device by sending signals to different microprocessor on how to components in it handle the interrupt 5. often small and low-cost device, o 2 interrupt controller chips 8259A components may be chosen to minimize can also be cascaded with the size integrated interrupt controller of 80186 6. actual processor used to implement can vary widely o interrupt controller performs the function of master controller Additional Circuits of Microcontrollers 1. Analog to Digital Converters (ADC): This electronic circuit is added to convert external signals to digital signals  2. Counter arrays: A few counter circuits temporary variables will use the are added to microcontroller for pulse available memory in SRAM generation. MCU has various modules such as 3. Watchdog Timers (WDT): This timer is Timer/Counter, ADC (Analog-to-Digital used to reset the microcontroller if Converter), DAC (Digital-to-Analog program execution hangs up Converter), USART (Universal Synchronous Asynchronous Receiver 4. Pulse Width Modulation (PWM) Transmitter), SPI (Serial Peripheral circuit: PWM circuit is used for speed Interface), Analog comparator, control of DC Motors Arduino can be programmed using the 5. Universal Synchronous and Arduino IDE Asynchronous Receiver AVR uses a Harvard architecture – with 6. Transmitter (USART) circuit: This separate memories and buses for circuit is used for serial data transfer program and data 7. Phase Locked Loop (PLL) circuit: instructions in the program memory are This circuit is used for synchronous executed with a single level pipelining communication program memory is in-system 8. External bus controllers: This circuit is reprogrammable flash memory used for controlling the bus system to connect static (RAM/ROM) and dynamic (SDRAM) memories. Registers and Pointers register is nothing but a flip-flop ATmega328P Architecture (Memory storage element) an Advanced Virtual RISC (AVR) there are pointers to store the addresses microcontroller of the memory locations, supports 8-bit data processing peripherals etc., the last 6 registers are used as pointers has 32KB internal flash memory has 1KB Electrically Erasable Programmable Read-Only Memory (EEPROM) if the electric supply supplied is removed it can store the data has 2KB Static Random Access Memory (SRAM) code will be compiled into a binary file and will be stored in the flash memory (non-volatile) AVR CPU executes the instruction from the flash memory one-by-one