Class Notes

History and Overview of Embedded Systems

Sources

  1. Class lecture
  2. Lecture Slides

Introduction

  • An embedded system is hardware combined with a software with either fixed or programmable capability. It is embedded because it is often found inside a product, like in cars, trains, elevators, etc.
    • hardware - components that controller monitors and controls
    • software - programs that command the controller what to monitor and how to control
  • It is a microprocessor or microcontroller that can be designed to perform a specific function or be made to be a part of a larger system.
  • An embedded computer system is a programmable computer that is not general-purpose.1

History

DateKey Event
1960The Apollo Guidance System was the first to utilize an embedded system
1965The Minuteman Missile Guidance System used a computer called the D-17B
1968The Volkswagen 1600 was released and it was the first vehicle to use an embedded system
1971- Texas Instruments engineers, Gary Boone and Michael Cochran, made the first microcontroller/microcomputer

- September 17: the TMS1802NC, a single-chip microcontroller, was used for a four-function calculator.
1987The release of the first embedded OS, VxWorks
1996The release of Microsoft’s Windows embedded CE
late 1990sThe release of the first embedded Linux system
2013$140 billion achieved by the embedded market

Characteristics of an Embedded System

  • Designed for a specific task (as opposed to general tasks such as playing video games, editing documents, etc.)
  • Connected with peripherals to connect with input and output devices
  • Runs in real-time
  • Minimal user interface
  • Limited memory (no secondary memory), less power consumption, and low cost
  • All of them have chips—either microprocessor or microcontroller—with code that governs the system.

Typical Embedded System Structure

  1. Sensor2
  2. Microcontroller
    1. ADC
    2. Memory3
    3. FGPA and ASIC (Application-Specific Integrated Circuit)
    4. CPU (or Microprocessor)4
    5. DAC
  3. Actuator5

Microprocessor Vs Microcontroller

MicroprocessorMicrocontroller
Functional blocks: register, ALU, timing, and control unitsFunctional blocks: RAM, timer, parallel I/O, ADC, and ADC
Uses external memoryData and code is inside the microcontroller
For general-purpose computer systemsFor application-specific dedicated systems
For multitaskingSingle-task oriented
Freedom in choosing the number of memory or I/O ports neededMemory or I/O is fixed and tailored to a specific task
Heavy and high costLightweight and low cost
More space and power neededLess space and power needed

Microcontrollers

  • They are single chip computers made to read input devices, process data, and control output devices.
  • They execute only a single application
  • They run on a single integrated circuit, consisting of a CPU, RAM, ROM, and I/O ports

Prominent Microcontroller Manufacturers

ManufacturerDescription
Microchip Technology- Microchip Technology was widely known for their 8-bit, 16-bit, and 32-bit PIC microcontrollers

- PIC microcontrollers were popular because they were easy to use, were widely available, and offered countless of support resources.
Atmel- They are currently acquired by Microchip

- They were known for their 8-bit microcontrollers, the AVR family. These were flexible and did not consume much power.
Cypress Semiconductor- They are currently acquired by Infineon Technologies

- They were known for microcontrollers which included the PSoC (Programmable System-on-Chip) family. These microcontrollers were highly customizable and flexible due to their integrated programmable analog and digital blocks
Espressif SystemsThey offered the ESP8266 and ESP32, which were popular because they were Wi-Fi and Bluetooth modules and SoCs that had built-in wireless connectivity (ideal for IoT applications)
Freescale SemiconductorThey offered the ColdFire and Kinetis microcontroller families. These were used for applications including automotive to industrial control.

Applications of Microcontrollers

Microcontrollers are embedded in devices for control. They are involved in the following areas:

  • Educational robotics
  • Research robots
  • Helpful robots
  • High-tech and aerospace use
  • Process control and technical education
  • Government/Peripherals office automation
  • Industrial control
  • Communications/Telecommunications networking
  • Automotive/Transportation systems and equipment
  • Consumer electronics/entertainment multimedia
  • Electronic instruments/ATE/design and test equipment

Types of Microprocessors

  1. Microcontroller, which includes I/O devices and on-board memory
  2. Digital Signal Processor (DSP), which are microprocessors tailored for digital signal processing
    • Requires external memory
    • Contains Multiply-Accumulate (MACs) units
  3. Typical embedded word sizes: 8-bit, 16-bit, 32-bit

Automotive Embedded Systems

  • High-end cars may have 100 microprocessors, whereas low-end ones use 20+.
    • 4-bit microcontroller checks seat belt
    • 16/32-bit microprocessor controls engine
  • BMW 850i brake and stability control system is comprised of the two:
    • Anti-lock brake system (ABS) - pumps brakes to minimize skidding
    • Automatic stability control (ASC+T) - controls engine for improving stability

Footnotes

  1. For this reason, PCs are not considered embedded computer systems despite being an essential component for producing embedded computing systems. On the other hand, a fax machine or clock made using a microprocessor is considered an embedded computing system. ↩

  2. It is connected to the actuator through the Electromechanical Backup and Safety ↩

  3. It communicates with a component outside of the microcontroller: software ↩

  4. It has parts that it communicates with outside of the microcontroller, particularly the human interface, diagnostic tools, and auxiliary systems (for power and cooling) ↩

  5. It is connected to the sensors through the external environment ↩

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