Bus is a structure that combines two or more component and interfaces. Any value entered on the BUS id readable by all components that are connected to it.

The units connected using a trascreiver, which is divided into two parts:

•  driver, which serves to drive the lines of the BUS
•  receiver, you need to read the values on BUS

 

Bus is a structure that combines two or more component and interfaces. Any value entered on the BUS id readable by all components that are connected to it.

The units connected using a trascreiver, which is divided into two parts:

•  driver, which serves to drive the lines of the BUS
•  receiver, you need to read the values on BUS

There are several types of bus:

• internal to a single chip
• for the connection of multiple chips on a card
• for connection of multiple boards in a system (backplane)

A BUS is normally divided into three groups of signals:

• data: normally are in a number equal to a multiple of 8
• address: identifies the slave with which the master wishes to communicate
• control: provide status information, timing

There are two categories of BUS:

• synchronous: in them the timing is dictated by a CK
• asynchronous: each process can have its own speed as send each of the control signals

In the synchronous bus is possible to introduce particular signals with the function of WAIT in such a way as not to be too slowed by the presence of memory or other devices much slower than others.

In each instant of time only one device can operate write operations on the BUS (master), and everyone can read simultaneously. So there is an arbitrage, which allows to solve problems related to the write request simultaneously by two different devices. Arbitrage can occur in several ways:

• centralized
• distributed