外文翻譯--關(guān)于pc機(jī)與單片機(jī)串行通信設(shè)計(jì)的實(shí)現(xiàn)-wenkub
2023-05-19 07:55:55 本頁(yè)面
【正文】 a fixed direction. (2) serial munication can be divided into two types: synchronous munication and asynchronous munication. 3 Asynchronous munication: a character in a character transfer, each character a a transmission, transmission of a character, begins with a start bit, and then transfer the character itself, ladies and gentlemen, then transfer check, finally ends with a stop bit the transmission of the characters. A transfer of the start bit, characters, ladies and gentlemen, parity, stop bits, constitute a plete set of information, known as the Frame (Frame). Between the frame and the frame can have any spare time. After the start bit is the least significant data. (1) a start bit is located in the character frame at the beginning, only one, for low level logic 0, is used to notify the receiving device, the sender to start sending data. Character on a line without transmission should be kept as 1. Receiving end constantly check the status of a line, such as continuous for later, 1 to a 0, know from a new character, should be ready to receive immediately. (2) data: data bits (D0 D7) j just behind the starting for, usually for 5 to 8, on the basis of data bits were transmitted from low to high order. (3) parity check bits, parity check bits only take up one, and immediately behind the data bits used to represent the serial munication using odd parity or even check, also can use this one (I/O) to determine the nature of this character represents more information in a frame (address/data, etc.). (4) stop bit: located in the character frame in the end, the characterization of the end of the characters, it must be a high level (logic 1). Stop bits can be 1, a, 2 a. On the receiving end after receiving the stop bit, know a character has been transferred, and at the same time to prepare for receiving the next character (as long as to receive a 0 is the new characters of the start bit). If stop, since is not followed by passing the next character, keep on a line as 1. Synchronous munication: synchronous transmission bit group is much larger. It is not independently send each character, each character has its own start and stop bits, but put them together to send together. We call these bined data frames, or frames for short. This design topic research between systems, data transmission and control system and peripherals. Serial port in system and ACTS as a connection between peripheral tasks and in serial munications with RS485 and RS232 serial interface 4 technology most widely used, this topic mainly studies design of RS485 serial port, and in order to meet the RS485 munication standard MAXIM pany has designed a model named MAX488 for this chip, the chip connotation is a drive and a receiver, with low power consumption at the same time, single + 5 v power supply, the drive has overload protection, without external ponents, etc. AT89C2051 MCU when executing mands to failure, can through the chip IMP813 microcontroller reset. It can also be awaken singlechip puter from sleep mode or idle mode. In the present AT89 series singlechip microputer serial port munication technology in the current popular solution is to adopt RS485 interface. It takes one and two bus interface, USES a half duplex munication bus difference level
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