(65)--CH2-7-3 Programming UART嵌入式系统原理.ppt

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1、第第2 2章章 单片机原理与应用单片机原理与应用Principles Principles and Applications of and Applications of MicrocontrollerMicrocontrollerChapter 2.7 UART2.7.3 Programming UART(1)Select Baud Rate,using timer1 Timer 1 should work in mode 2(Auto-reload 8-bit timer)TMOD=0 x21;/*-T1:Mode 2;T0:Mode 1*/Chapter 2.7 UART2.7.3 Pr

2、ogramming UART/Initialization of UART/*Baud Rate=(T1 overflow rate)*2SMOD/32T1 overflow rate=(fosc/12)/(256-TH1)So if Baud rate is 1200bps,TH1 will be(fosc=11.0592MHz)256-TH1=(11059200/12)/(1200*32)TH1=232=E8(Hex)*/TH1=0 xe8;/0 xfd;TL1=0 xe8;/1200bps/0 xfd;/*9600bps*/Chapter 2.7 UART2.7.3 Programmin

3、g UART(2)Set UART Working ModeSCON=0 x50;/*-Mode 1(SM0:SM1=01);REN=1*/Chapter 2.7 UART2.7.3 Programming UARTTR1=1;/Start timer1 to generate BAUD rate pulse(3)Making UART to work by start timer 1(4)Write to SBUF for sending SBUF=A;/Sending A(5)Read RI flag to determine the byte received while(RI=0);/

4、waiting for receivec=SBUF;/Receive the byte to variable c RI=0;/Clear the RI flag for next receiving Chapter 2.7 UART2.7 Summary(1)UART interface is used to transfer parallel byte to serial format.(2)Make serial communication very simple.(3)All the programmer has to do is to simply select serial port mode and baud rate.Then read/write the SBUF register.