MAT2006 Chapter Notes -Peripheral, Block Diagram, Microcomputer
10 Apr 2023
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The 8251 is a usart (universal synchronous asynchronous receiver transmitter) for serial data communication. As a peripheral device of a microcomputer system, the 8251 receives parallel data from the cpu and transmits serial data after conversion. This device also receives serial data from the outside and transmits parallel data to the cpu after conversion. 4. 3. 1 block diagram of the 8251 usart (universal synchronous asynchronous receiver. The 8251 functional configuration is programmed by software. Operation between the 8251 and a cpu is executed by program control. Table 1 shows the operation between a cpu and the device. There are two types of control word: mode instruction (setting of function, command (setting of operation) Table 1 operation between a cpu and 8251: mode instruction. Mode instruction is used for setting the function of the 8251. "wait for write" at either internal reset or external reset. That is, the writing of a control word after resetting will be recognized as a "mode instruction. "
