What is the resident bus mode and what is the bus mode?

or if the components apply to use the bus at the same time, the bus control body should decide on a certain order of priority to ensure that only one high-priority applicant can obtain the right to use the bus at any one time.

There are two types of bus adjudication: centralized adjudication and distributed adjudication.

Centralized adjudication implements the control function of the bus with a special component, which can be located on a device connected to the bus. When a device needs to transmit data to a shared bus, it must make a request before it can issue data when it is licensed. The adjudication part receives a bus usage request signal from each device and sends a bus permission signal to one of the devices.

Distributed adjudication distributes control functions across devices connected to the bus, which is generally fixed and preferred. Each device is assigned a priority number, and the device that makes the bus request sends its own priority number to the request line, forms a synthetic signal with the request signals of other devices, and reads this synthetic ruling signal to determine whether a higher priority device applies for the bus. This allows the highest priority devices to gain access to the bus.

Bus Judgment Control (Bus Adjudication): When multiple devices need to use the bus for communication, a strategy is adopted to select one device to use the bus.

There are two ways of bus adjudication: centralized and distributed.

Centralized: The control logic is made in a dedicated bus controller or bus adjudicator, and a specific adjudication algorithm is used to adjudicate by centralizing all bus requests.

Distributed: There is no dedicated bus controller, and its control logic is scattered across individual components or devices.

The functions of the system bus are logically divided into three parts: the address bus, the data bus, and the control bus. The data transmission bus, bus, and bus connect a set of parallel wires to the main components of the computer, so that electrical impulses can be transmitted between the connected parts.

The control bus contains several control signals that represent routing time-sharing and the system.

1) The CPU controls the external devices through the control bus.

2) The width of the control bus determines the CPU's ability to control external devices.

3) The control bus is the sum of the number of control lines.

Any microprocessor needs to be connected to a certain number of components and peripherals, but if each component and each peripheral device are directly connected to the CPU with a set of lines, the wiring will be complicated or even difficult to implement. In order to simplify the hardware circuit design and simplify the system structure, a group of lines is commonly used, configured with appropriate interface circuits, and connected with various components and peripheral devices, and this group of common connection lines is called a bus. The use of the bus structure facilitates the expansion of components and equipment, especially the development of a unified bus standard makes it easy to realize the interconnection between different devices.

--The bus in the microcomputer generally has an internal bus, a system bus and an external bus. The internal bus is the bus between the peripheral chips and the processor inside the microcomputer, which is used for the interconnection at the chip level; The system bus is the bus between each plug-in board and the system board in the microcomputer, which is used for the interconnection of the plug-in board at the first level; The external bus is the bus between the microcomputer and the external device, the microcomputer is a kind of device, through the bus and other devices for information and data exchange, it is used for the interconnection at the device level.

1) Bus ruling: decide which master device to use the bus;

3) Data transmission stage: data exchange between master and slave devices;

4) End stage: the relevant information is revoked on the bus, and the right to use the bus is relinquished.

The purpose of bus communication control is to solve the problem of how the master and slave devices know the start and end of the transmission, and how the two parties coordinate the data communication.

There are four types of communication: synchronous, asynchronous, semi-synchronous, and detached.

1) Synchronous communication control.

There is a clock signal line in the control line, all devices connected to the bus get the timing signal from this common clock line, and the clock signal of a certain frequency defines the time period at equal intervals, and this fixed time period is a clock cycle, also called the bus cycle.

2) Asynchronous communication mode.

Three lines of control:

datardy: the data is ready, the slave device has prepared the data, and the master device can take the data and send it to the ground data line at the same time;

3) Semi-synchronous communication control.

In order to solve the problem of noise sensitivity in asynchronous communication, clock signals are generally introduced into the asynchronous bus, and timing signals such as ready and answer are valid on the rising edge of the clock, so that the effective time of the signal is limited to the moment when the clock arrives, and is not interfered by signals at other times. This type of communication is called semi-synchronous communication.

4) Separate communication control.

The basic idea: divide a transfer operation transaction into two sub-processes. In the first subprocess, after the master device A obtains the right to use the bus, it sends the requested transaction type (i.e., bus command), address, and other relevant information (such as the number identifying the identity of the master device) to the bus, and records these information from device B.

As soon as the master sends this information, it releases the bus so that it can be used by other devices. In the second sub-process, after receiving the information sent by master control device a from device b, carry out corresponding operations according to the command it requests, when the data required by master control device is prepared, slave device b then requests to use bus, once the right to use is obtained, then slave device b sends the number of master control device a and the data and the like to the bus, so that master control device a can receive data.

Advantage: Increases the total effective bandwidth of the entire system.

Disadvantages: The control is quite complex and overhead.

Bus is a common communication trunk that transmits information between various functional parts of a computer, and it is a transmission harness composed of wires. The bus is an internal structure, it is a common channel for CPU, memory, input and output devices to transmit information, the various components of the host are connected through the bus, and the external equipment is connected to the bus through the corresponding interface circuit, thus forming a computer hardware system.

Classification of buses:

1. Data bus: Transfer data that needs to be processed or stored back and forth between CPU and RAM.

3. Control bus: transmit the signal of the microprocessor control unit to the peripheral equipment.

4. Expansion bus: the bus for data communication between external devices and computer hosts, such as ISA bus and PCI bus.

5. Local bus: an extended bus that replaces higher speed data transmission.

The bus system is a pair of wires with multiple devices, and the devices have address codes to identify! The so-called bus generally refers to a set of transmission lines that transmit information to one or more destination parts in one or more source parts through time-sharing multiplexing. It's a public channel for transferring data from your computer!

What is a bus system and what are the benefits.

Dallas Semiconductor has designed a high-resolution programmable digital temperature sensor, the device receives power from the data line, and because the digital transmission part only uses one microcontroller interface line, the sensor is named 1-wire digital thermometer.

The original 1-wire bus is the data line that can communicate with a digital temperature sensor. The development of first-line bus technology has led to a series of first-line working components, instruments, and first-line buses that can communicate with all first-line components and instruments without restrictions, because each sensor or digital device produced by DALLAS is unique, and each device has a unique digital code.

The first-line bus is one of the most competitive fieldbuses. It has many advantages such as being able to communicate digitally with the computer, large bus load, simple wiring, high precision, stable performance, and low performance, and is an advanced realm of industrial field system design.

The real advantage of the first-line bus is that as a signal source, there is no need to think about how to solve the communication protocol problem; In the vast majority of cases, the number of sensors connected to the bus is irrelevant; In most cases, there is no need for an additional power supply. The development of the first-line bus has constituted a strong impact on the communication protocol barriers between various buses, and its biggest benefit is to make it more convenient for users.

The first-line bus technology is still improving, and new devices and instruments are constantly introduced, and the transmission distance and transmission speed still need to be improved, but in most of the fields, the first-line bus is simple, economical and practical.