'''Embedded microprocessors''' are essentially [[microprocessors]] that are used in everyday electronic devices, such as cellular telephones, household appliances, automobiles, or virtually any electronic device you could think aboutof. Unlike [[microprocessors]], which are usually used in [[computer systems]], embedded microprocessors are usually designed to perform a certain task and the user seldom has to interact with it. ▼
Although not seen, embedded micrprocessors are all around us. It is estimated that in 1997, there were about 30 million microprocessor chips built for [[ PCpersonal computer]] use, while there were around 3 billion built for embedded purposes.[[http://www.cheshirehenbury.com/embedded]] ▼▲'''Embedded microprocessors''' are essentially [[microprocessors]] that are used in everyday electronic devices, such as cellular telephones, household appliances, automobiles, or virtually any electronic device you could think about. Unlike [[microprocessors]], which are usually used in [[computer systems]], embedded microprocessors are usually designed to perform a certain task and the user seldom has to interact with it.
▲Although not seen, embedded micrprocessors are all around us. It is estimated that in 1997, there were about 30 million microprocessor chips built for [[PC]] use, while there were around 3 billion built for embedded purposes.[[http://www.cheshirehenbury.com/embedded]]
==Characteristics of Embedded Microprocessors==
Embedded microprocessors, although similar to normal [[microprocessors]], usuallyrequire arelittle neverto controlledno byhuman humansinteraction. If this were the case, then why wouldn't we just hook up a [[computer]] to every electronic device? This would be too cumbersome and would require someone to be with the device all the time to control it. Instead, embedded microprocessors interact with the world without any need for a human "supervisor.". So how does the processor know what to do and when?
===Interrupts===
Embedded microprocessors interact with their environmentenvironments through an [[interrupt]] system. Interrupts are basically electronic signals sent from external devices that let the processor know that they are done retrieving some data, or converting a signal, or whenever they need to use the processor. The processor then enters it'sits interrupt handler (which is usually just another program) and decodes the source of the interrupt to take the correct action.
So, now we know a little about how embedded microprocessors interact with the world. A natural question at this point is where are the programs that the processor executes.
===Programs===
Well, likeLike any [[computer]], the programs are stored in memory. [[PC]]'s have a relatively large memory, and are able to execute large, complicated programs. Since we are dealing with an [[embedded system]], memory is an important issue. Keeping in trend with the miniaturization of electronics, this leaves usthe embedded microprocessor without large amounts of available memory. This isn't too big an issue, however, since the programs run by embedded microprocessors are usually fairly short and straightforward. So these small programs can fit onto memory built onto the chip that the processor is on.
===Other Common Microprocessor Features===
Aside from the memory and interrupt system, embedded processors also use a variety of other devices which are built onto the chip as well. Since embedded processors are usually used to control devices, they sometimes need to accept input from the device they are controlling. This leads us tois the needpurpose forof anthe [[analog to digital converter]]. Since processors are built to interpret and process digital data, i.e. 1's and 0's, they won't be able to do anything with the analog signals that may be being sent to it by a device. So the [[analog to digital converter]] is used to convert the incoming data into a form that the processor can recognize. There is also a [[digital to analog converter]] that allows the processor to send data to the device it is controlling.
In addition to the converters, many embedded microprocessors include a variety of timers as well. One of the most common types of timers is the [[Programmable Interval Timer]], or PIT for short. A PIT just counts down from some value to zero. Once it reaches zero, it sends an interrupt to the processor indicating that it has finished counting. This is useful for things such as thermostats, which periodically test the temperature around them to see if they need to turn the air conditioner on, the heater on, etc.
==Embedded Microprocessors vs. General Microprocessors==
Although embedded microprocessors are similar to regular processors used in [[computers]], there are some differences that will be discussed below.
So, why are embedded microprocessors not the same as normal computing [[microprocessors]]? Essentially, they don't need to be as sophisticated as processors that a [[computer]] might use. [[Computers]] generally do all sorts of computations, yet [[embedded systems]] are generally specific to the type of job they are designed for.
===Speed Issues===
==References==
[[ http://www.cheshirehenbury.com/embedded]]
[[Category:Microprocessors]]
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