An Embedded system can be defined as a computer system designed to perform the specific functions.
A specialized computer system that is part of a larger
system or machine. Typically, an embedded system is housed on a
single microprocessor board with the programs stored in ROM. Virtually all
appliances that have a digital interface -watches, microwaves, VCR's, cars --
utilize embedded systems. Some embedded systems include an operating system,
but many are so specialized that the entire logic can be implemented as a
single program.This generally goes
with real-time computing constraints.
Architecture and Programming of 8051
Micro controllers :
Learn in a very quick and easy way to program 8051
micro controller using many practical examples we have provided for you. Despite
its relative old age, 8051 is still the most commonly used micro controller at
present. The blog contains details of its architecture and many
practical examples, both simple and complex, useful program routines,
instructions on handling the programmer for Atmel 51 series, and the guide on
using the development systems for Atmel micro controllers.
Introduction :
It was electricity in the beginning....The people were happy
because they did not know that it was existing all around them and that it
could be utilized. It was fine. And then Faraday came and the stone has started
rolling slowly...
During the time, the first machines using a new sort of
energy appeared accompanied with people who knew something about electricity. A
long time has passed since then and just when civilization got used to this
innovation and stopped paying attention to what a new generation of specialists
were doing, someone came up with an idea that electrons could be a very
convenient toy being closed in a glass pipe. At first sight, it was only a good
idea, but there was no return, electronics was born and the stone continued
rolling down the hill faster and faster...
A new science - new specialists. The blue coats were
replaced with white ones and people who knew something about electronics
appeared on stage. While the rest of the humanity were passively watching in
disbelief what was going on, within plotters two fractions appeared- “software-oriented”
and “hardware-oriented”. A bit younger than their teachers, very enthusiastic
and full of ideas, both of them kept on working but separate ways. While the
first group had a stable development, hardware-oriented people, driven by
success, soon threw caution to the wind and invented transistor.
Up till that moment, the things could be more or less kept
under control, but broad publicity was not aware of seriousness of the
situation and it soon led to a fatal mistake! Being naive in belief that using
cheap tricks could slow down technology development as well as developing of
the world, mass market opened its door to the products of Electronics Industry,
closing a magic circle therefore. Components’ prices fell rapidly becoming
available for use to younger population. The stone was falling freely...
The first integrated circuits and processors have soon
appeared, which enabled for computers to drop down in price. The computers have
started to develop their own production. The prices dropped down again and
Electronics got new adherents. It appeared everywhere. Another circle has been
closed! Ordinary people got hold of computers and computer era has begun...
While this drama was going on, hobbyists and professionals,
protected by anonymity, were working hard on their projects , although split in
two big groups. Then, someone has again remembered: Why should not we make an
universal component? It would be a cheap and universal integrated circuit that
could be programmed and used in any field of electronics, device and wherever
needed. Technology has been developed enough, market exists, why not? So it
happened, body and spirit are united, the circuit is created and called
MICRO CONTROLLER.
What are micro controllers and for what purpose they are used ?
- As all other good things, this powerful component is basically very simple and is obtained by uniting tested and high- quality "ingredients" (components) as per following receipt:
- The simplest computer’s processor is used as a "brain" of the future system.
- Depending on the taste of the producer, it is added : a bit of memory, a few A/D converters, timers, input/output lines etc.
- It is all placed in one of standard packages.
- A simple software that will be able to control it all and about which everyone will be able to learn has been developed.
- Three things have had a crucial impact on such a success of the microcontrollers:
- Powerful and intelligently chosen electronics embedded in the microcontrollers can via input/output devices ( switches, push buttons, sensors, LCD displays, relays…) control various processes and devices such as: industrial automatics, electric current, temperature, engine performance etc.
- A very low price enables them to be embedded in such devices in which, until recent time it was not worth embedding anything. Thanks to that, the world is overwhelmed today with cheap automatic devices and various “intelligent” appliences.
- Prior knowledge is hardly needed for programming. It is sufficient to have any kind of PC (software in use is not demanding at all and it is easy to learn to work on it) and one simple device (programmer) used for “transffering” completed programs into the microcontroller.
- Therefore, if you are infected with a virus called electronics, there is nothing left for you to do but to learn how to control its power and how to direct it at the right course.
- How does microcontroller operate?
- Even though there is a great number of various microcontrollers and even greater number of programs designed for the microcontrollers’ use only, all of them have many things in common. That means that if you learn to handle one of them you will be able to handle them all. A typical scenario on whose basis it all functions is as follows:
- Power supply is turned off and everything is so still…chip is programmed, every thing is in place, nothing indicates what is to come…
- Power supply connectors are connected to the power supply source and every thing starts to happen at high speed! The control logic registers what is going on first. It enables only quartz oscillator to operate. While the first preparations are in progress and parasite capacities are being charged, the first milliseconds go by.
- Power supply connectors are connected to the power supply source and every thing starts to happen at high speed! The control logic registers what is going on first. It enables only quartz oscillator to work. While the first preparations are in progress and parasite capacities are being charged, the first milliseconds go by.
- Voltage level has reached its full value and frequency of oscillator has became stable. The bits are being written to the SFRs, showing the state of all periph erals and all pins are configured as outputs. Everything occurs in harmony to the pulses’ rhythm and the overall electronis starts operating. Since this moment the time is measured in micro and nanoseconds.
- Program Counter is reset to zero address of the program memory. Instruction from that address is sent to instruction decoder where its meaning is recognised and it is executed with immediate effect.
- The value of the Program Counter is being incremented by 1 and the whole process is being repeated...several million times per second.