Archive for July, 2016

Introduction to Embedded Systems

Written by Rush PCB Inc on . Posted in PCB, PCB Manufacturing

Embedded Systems

We are all familiar with the concept of a computer. Modern computers are able to perform a wide variety of tasks, and have input from their users in the form of a keyboard, touch screen or mouse. When a computer system is designed to function as a component within a larger system it is called an embedded system.

 

Effectively, an embedded system could be considered to be a computer in its own right, but with pre-set programing that allows it to complete specific tasks, and with very little opportunity for input from users. While there is minimal opportunity to interact with the embedded system, it still requires hardware to operate, and software to drive the system. The larger system could be mechanical or electrical. There may be real-time computing constraints to the system. The result of using an embedded system in this manner is that larger systems can be controlled in a regular manner, allowing common daily use. Nearly all microprocessors are manufactured to be part of larger embedded systems.

 

Embedded systems may be as simple as a single chip, or can be complex, with multiple units. Complex embedded systems may include peripheral devices and networks, mounted within a fixed structure.

 

We use embedded systems on a daily basis without realizing it. A simple example is the computer that controls an elevator. User input is from a button. The elevator has a program to start the engine, move the elevator car to the relevant floor, open the door, and await further instructions.  Another example is a set-top decoder for digital television. As users, our interaction is limited to choosing channels. The computer takes the digital signal, and transforms it into a format that will produce a picture on the television screen.

 

When programmers talk about real-time computing, they indicate that the embedded system must perform its designated task to maintain the flow of information to the larger system and keep the system operating. In our examples, if the elevator needed to calculate factors before moving the car, people would become frustrated. Similarly, if the set-top box needed to stop accepting new signals while it transformed or decoded the signals already received, we would have stop-start television viewing. Other everyday examples of embedded systems include MP3 players, digital cameras, or assembly line controllers in factories.

 

Embedded systems are based on either microprocessors or microcontrollers. A microprocessor uses external chips and peripheral interfaces, while a microcontroller uses a CPU and has integrated memory or peripheral interfaces. Irrespective of whether the embedded system is based on a microprocessor or a microcontroller, the system may be general purpose, specialized, or customer designed for specific applications.

 

Design engineers can optimize embedded systems to reduce the size, and the associated cost because there are few direct interfaces required. There are a range of properties that accompany embedded systems. They tend to be smaller than general-purpose computers. They are likely to have lower levels of power consumption, low unit costs to manufacture, and a small size. As they are designed for a specific purpose, they are generally more challenging to interact with and program.

 

Microelectronics – An introduction

Written by Rush PCB Inc on . Posted in PCB, PCB Assembly and component, PCB Manufacturing

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Electronics is a general term for the field of science that involves managing electric currents through circuits. Microelectronics is one of the sub-categories of electronics. Microelectronics specifically relates to manufacture of very small electronic circuits. It also incorporates the study and engineering of the circuits. Fundamentally, the term ‘micro’ relates to the measurement scale of a micrometer (1 x 10-6 meters). Microelectronics relates to electronic components at this scale or smaller.

When standard electronic components are assembled, the options include capacitors, inductors, resistors, diodes, and transistors. The same range of components is available in a microelectronic product. Wiring of microelectronic components can be challenging due to the sizes involved. Techniques have been developed such as wire bonding to help ensure effective circuits are developed, incorporating the components, leads and pads.

The cost of manufacture of microelectronics can be higher than that of standard electronics due to the need for specialized equipment. This is largely as a result of the set-up costs, but once the set-up has been addressed, the ongoing cost of manufacture can be cost effective.

Microelectronics has become a crucial factor in many aspects of our modern society (and economy). Microelectronics has been described as ‘the enabler’ of modern information technology. Microelectronic components are used in a broad range of industries including computers and software, telecommunications and media, commerce, logistics and transportation, natural science and medicine, power generation and distribution, finance, and administration.

As an example of the increase in use of microelectronics, the value of microelectronics in a modern car will be at least 15% of the value of the vehicle. In some well-equipped vehicles, the value of microelectronic components may be 30% of the value of the vehicle. The range of systems in a car that need microelectronic circuits include the electronic ignition, ABS brakes, ESC stability systems, air bag triggers, anti theft systems, travel computers, integrated instrument panels, automatic climate control systems… the list is endless. When a modern car is serviced, the technician will connect the car’s computer system to identify the mechanical performance and address any issues.

Over time, the scale of microelectronics has steadily decreased. According to Moore’s Law, the number of transistors in a dense integrated circuit has doubled approximately every two years. The law was first identified in 1965, and had continued to be valid for the last 50 years. A modern microprocessor chip is about 3 cm2, and holds 100 million transistors. The same device using traditional 3mm3 transistors would require a volume of a cube measuring 1.4m; and that actually wouldn’t account for the space required for the wiring.

With the decrease in scale, ‘parasitic effects’ have become a challenge for engineers. Parasitic capacitance is defined as ‘an unavoidable and usually unwanted capacitance that exists between the parts of an electronic component or circuit simple due to their proximity to each other’. Engineers working in the field of microelectronics must constantly seek new ways of compensating for (or minimizing) parasitic effects.

In summary, microelectronics as a field has become a crucial aspect of our society and our daily lives, from an obvious level such as a cell phone to a complex range of integrated operations in a car.