I/O Ports of Microprocessors and Microcontrollers....

[Rohit Chatterjee]

One of the differences between mircroprocessors and microcontrollers is that The latter has i/p and o/p ports,while the former doesnt....Now i dont really get this point...What is an i/p or o/p port supposed to do???Does it mean that u can connect a microcontroller directly to a say a segment LED display....but for a microprocessor u hav to go through an interfacing device???Moreover what does this interfacing device actually do???

 

[Papabravo]

Input Ports and Output Ports are "addressable" entities in the processor architecture that allow values to be read or written from or to them. In a single chip device that address decoding and "interfacing" is done internally so that the actual pins can be used as digital inputs, digital outputs, analog inputs, or analog outputs.

In a microprocessor you have to decode the address and route data to or from the processor. That is the purpose of interfacing.

Last question is weather you can connect a device like a 7-segment directly to a processor's pins. You can IF, the processor pins can supply sufficient current to light the segments. Some can, but most cannot.

 

[Rohit Chatterjee]

Suppose we wish to display the data stored in the accumulator by means of the LED display....Can we do it just by connecting the LED display to the microprocessor????Dont we need some interfacing device???Assuming that the microprocessor provides the necessary current....

 

[Nigel Goodwin]

Suppose we wish to display the data stored in the accumulator by means of the LED display....Can we do it just by connecting the LED display to the microprocessor????Dont we need some interfacing device???Assuming that the microprocessor provides the necessary current....

A micro-processor is just one of many components required to make a 'computer' - a micro-controller is a complete 'computer' on a single chip.

Micro-processsors don't have 'ports', they are one of the many external chips required to make a useable computer with it - amongst other things, the port chips have current sinking and sourcing capacity, which the uP doesn't.

 

[Rohit Chatterjee]

Am familiar with some other properties of microprocessors,including the ones u mentioned....its the port stuff which confuses me....

 

[Nigel Goodwin]

Am familiar with some other properties of microprocessors,including the ones u mentioned....its the port stuff which confuses me....

For a micro-processor it has to latch the output signals, and provide current drivers.

Bear in mind a micro-processor essentially only has address and data lines, you use those to select either memory or devices, ports etc.

 

[Rohit Chatterjee]

Hmmm....makes sense...thnx 2 both of u guys....

 

[BrownOut]

I like to think of the I/O's on my microcontroller in terms of the parallel port on my PC. From a structural as well as programming standpoint, they are very similar.

 

[Rohit Chatterjee]

Sorry but i hav absolutely no idea about how a parallel port functions....or a serial port for tht matter....

 

[BrownOut]

This might help. **broken link removed**