bi directional only one device at a time can have its outputs enabled this

# Bi directional only one device at a time can have its

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¨ bi-directional ¨ only one device at a time can have its outputs enabled, ¨ this requires the devices to have three-state output
Microprocessor-Based System - Expanded System 1. Note the directions of busses 2. What is the width of the address bus? 3. What is the value of the Address but to access the first register of the R/WM? You must know how to draw it! Remember: 111 1111 1111 = 7FF = 2^11-1 = 2047 2^11=2K=2048 2^11 Requires 11 bits
2K Registers or bytes of memory 000 What? How many bits 001 2K Registers or bytes of memory 800 801 How much memory do we have? What? How many bits Example
2K (2^11 = 2048) Registers or bytes of memory 000 2^11 -1=7FF Requires 11 bits 001 2K (2^11 = 2048) Registers or bytes of memory 800 FFF Requires 12 bits For a total of 4095 bytes 801 Total of 4K bytes of memory: 2^12 (FFF) à 12 bits ; last values 2^12-1 = 4096-1 Example
1G bytes of memory 000 2^30 -1=3FFF FFFF Next number: 4000 0000 (in Hex) 001 Example 8 bits 30 bits!
800 FFF Example of an 8-bit MPU RAM 2K ROM 2K A15 A0 D7 D0 8-bit
So what are microcontrollers?
What is a Microcontroller? n A microcontroller is a small computer on a single integrated circuit containing ¨ processor core, ¨ memory, ¨ programmable input/output peripherals n Used for specific (embedded) applications
Embedded controllers n Used to control smart machines n Examples: printers, auto braking systems n Also called microcontrollers or microcontroller units (MCU)
Embedded controllers Software Characteristics n No operating systems n Execute a single program, tailored exactly to the controller hardware n Assembly language (vs. High-level language) ¨ Not transportable, machine specific ¨ Programmer need to know CPU architecture ¨ Speed ¨ Program size ¨ Uniqueness
Microcontroller Unit (MCU) Block Diagram n An integrated electronic computing and logic device that includes three major components on a single chip (System- on-Chip (SOC)) ¨ Microprocessor ¨ Memory ¨ I/O ports n Includes support devices ¨ Timers ¨ A/D converter ¨ Serial I/O ¨ Parallel Slave Port n All components connected by common communication lines called the system bus.
First Microcontrollers n IBM started using Intel processors in its PC ¨ Intel started its 8042 and 8048 (8-bit microcontroller) – using in printers n Apple Macintosh used Motorola n 1980 Intel abandoned microcontroller business n By 1989 Microchip was a major player in designing microcontrollers ¨ PIC: Peripheral Interface Controller
Different Microcontrollers (MCU) A more complete list is here: What is the difference? 8/16/24/32 bits Architecture Package Capability Memory Software (IDE)/cloud ADC (10-12 bit)
MCU Architecture n RISC ¨ Reduced instruction set computer ¨ Simple operations ¨ Simple addressing modes ¨ Longer compiled program but faster to execute ¨ Uses pipelining ¨ Most embedded system n CISC ¨ Complex instruction set computer ¨ More complex instructions (closer to high-level language support) ¨ x86 standard (Intel, AMD, etc.), but even in the mainframe territory CISC is dominant via the IBM/390 chip Bench marks: How to compare MCUs together MIPS: Million Instructions / second (Useful when the compilers are the same)

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