* Car lock remote key fob.
* TV Remote control.
* Security system.
* Electronic safe.
* Car anti lock braking system.
* Satelite decoder.
* DVD player.
A microcontroller is an all in one electronic integrated circuit with built in processor memory and peripherals that is also re-programmable.
You may not be able to recognize the microcontroller as for cost savings its cheaper to build an ASIC (Application Specific Integrated Circuit). This is a custom chip designed only for the product which is mass produced in milliions making the cost of the device far cheaper than using an individual microcontroller.
Nevertheless each system is based on a microcontroller.
Electronic Circuit design has progressed from individual transistors which are based on silicon to placing thousands and then millions of transistors on a single silicon wafer. The transistors, arranged in the correct configuration, perform different functions such as time delays, boolean logic, memory etc.
7400 series logic
Still available today are the older 74 series devices. These are ICs encased in plastic with connection pins on the outside and each one performs a different well defined function.
By grouping these devices together you can make up circuits by connecting the pins of the device to pins of other devices. About 20 years ago this was the only way of making digital electronic systems and you would typically have racks of circuit boards each with 50 of these devices wired up.
Of course the disadvantage of these racks of circuit boards is that once you have designed the board you can not change it so you had to be absolutely sure that the design was perfect. If it was not then you had to start over - and for a complex system that means spending money on a new circuit board and spending time re-designing it.
With the advance of manufacturing techniques more transistors can be put on the silicon wafer - and if you can get more transistors on a wafer there are two advantages.
1. Increased functionalty.
2. Higher speed.
Smaller transistors means smaller physical problems (capacitance slows down a devcie - so a smaller device has less) and they also use less current. Less current means less power and less power means less heat and less heat means that the device can operate faster.
Given enough transistors you can design a circuit (or Integrated Circuit - ICs) to perform virtually any function you can think and using a special form of transistor (flash memory) means that the device can store information for years - this memory is also re-programmable.
Arduino Battery Charger: A very useful project that lets you charge 'un-rechargeable' alkaline batteries!
The Essential Guide to the 74HC595; What it is and how you can easily use one in any of your projects.
How to use the MCP23017 to increase your I/O by 16 pins (or more) and use its interrupt system.