What is interface technology?

1. What is an interface? The interface is the connection component between the microprocessor CPU and the external world. It is a transfer station for information exchange between the CPU and the external world. 2. Why do I need to set interfaces between the CPU and peripherals? There are four main reasons for setting interfaces between the CPU and peripherals: (1) signal incompatibility between the CPU and peripherals, including Function Definition, Logic definition, and timing relationship of the signal line (2) the speed of the CPU and peripherals does not match, the CPU speed is fast, and the speed of the peripherals is slow (3) if the interface is not passed, the CPU directly controls the operations of the peripherals, this will make the CPU poor to deal with peripherals, greatly reducing the CPU efficiency (4) if the peripherals are directly controlled by the CPU, the hardware structure of the peripherals will depend on the CPU, it is detrimental to the development of peripherals. 3. What functions should interfaces of a microcomputer provide? The Microcomputer Interface generally has the following functions: (1) the CPU command execution function: the CPU sends the control commands for peripherals to the command register (command port) in the interface circuit, after analysis, the function of controlling peripherals (2) Returning the peripheral status is completed through the Status Register (status port), including the normal working status and fault status (3) data buffering function: the data register (data port) in the interface circuit transfers the data transmitted between the CPU and peripherals (4) device addressing function: the CPU can only exchange data with one peripheral at a time, the address signal sent by the CPU goes through the address decoding circuit in the interface circuit to select the function of I/O device (5) signal conversion: when the signal function definition, logical relationship, level, and working sequence of the CPU and peripherals are incompatible, the interface circuit must complete the signal conversion function (6) data width and data format conversion function: because the CPU processes data in parallel, when the peripherals adopt the serial transmission mode, the interface circuit must complete the conversion between strings and convert the data format. 4. What is the role of Interface Technology in Microcomputer Applications? With the rapid development of computer technology, computer applications become more and more extensive. However, in a microcomputer system, the powerful functions of the microprocessor can be achieved only through external devices, and the information exchange and communication between the peripherals and the microprocessor are implemented through interfaces, interface technology has become a key technology, which directly affects the functions of the Microcomputer System and the promotion and application of the microcomputer. 5. What components does the interface circuit hardware generally consist? The hardware of the interface circuit is generally composed of the following parts: (1) basic logic circuit: including command registers, status registers, and data buffer registers, is the core of the interface circuit (2) port address decoding circuit: implements the device selection function (3) supply circuit: the function module circuit added according to different tasks and functional requirements. 6. What are the components of the Software Control Program of the interface circuit? The software control program of the interface circuit generally includes the following program segments, and each part of the program is mutually infiltrated and integrated: (1) initialization program segment: programming the programmable interface chip (2) transfer Method Processing Program segment: different transfer methods (query, interrupt, DMA) Different program segments (3) Main Control Program segment: program segment for interface task completion (4) program termination and exit program segment: program section for hardware protection in the interface circuit before exiting (5) auxiliary program section: man-machine conversation, menu, etc. 7. what are the forms of interface circuit structure? There are four main types of interface circuit structures: (1) fixed structure: unprogrammable interface circuit, simple structure, single function, fixed (2) semi-fixed structure: an interface circuit consisting of a PAL or GAL device. The function and working mode can be changed by modifying the internal logical expression. However, once the logical expression is burned into the chip, its functions and work methods are fixed. (3) programmable structure: Its functions and work methods can be specified by programming. It is flexible to use and can adapt to a wide range of features. (4) intelligent structure: the chip itself is a microprocessor, and all the management of peripherals is completed by intelligent interfaces, such as I/O processor I0809 or general purpose single chip microcomputer 8. which data transmission methods are available between the CPU and the interface? Where are their applications? The data transmission modes between the CPU and the interface are query, interrupt, and DMA: (1) query mode: Mainly used when the CPU is not busy and the transmission speed is not high. Unconditional transmission is a special case of query. It is mainly used to control simple I/O devices or when the CPU knows the status of peripherals clearly. (2) interrupt mode: it is mainly used when CPU tasks are busy, especially suitable for real-time control and emergency handling (3) DMA mode (Direct Memory Access Mode ): it is mainly used for high-speed peripherals for mass data transmission.