文章目录

UART

原理图

模式 1

配置：

1 个起始位, 8 位数据, 1 个停止位；使用定时器 2 作为波特率发生器；允许接收、发送请求中断；将接收到的数据直接发回去，并反转P1.1端口的电平。

工程结构：

stc15w204s.h头文件：

声明有关 UART 和定时器 2 的特殊功能寄存器；声明有关 UART 和定时器 2 的特殊功能寄存器的位掩码；以及其他。

#ifndef __STC15W204S_H#define __STC15W204S_H//#include<reg51.h>#define INTERNAL_RC_OSCILLATOR_FREQUENCY_05529600HZ (5529600) /* 5.5296 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_06000000HZ (6000000) /* 6.0000 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_11059200HZ (11059200) /* 11.0592 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_12000000HZ (12000000) /* 12.0000 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_18432000HZ (18432000) /* 18.4320 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_20000000HZ (20000000) /* 20.0000 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_22118400HZ (22118400) /* 22.1184 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_24000000HZ (24000000) /* 24.0000 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_27000000HZ (27000000) /* 27.0000 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_30000000HZ (30000000) /* 30.0000 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_33177600HZ (33177600) /* 33.1776 MHz */#define INTERNAL_RC_OSCILLATOR_FREQUENCY_35000000HZ (35000000) /* 35.0000 MHz */#define SYSTEM_CLOCK (INTERNAL_RC_OSCILLATOR_FREQUENCY_11059200HZ)/*** Interrupt Registers Definition*/sfr IE = 0xA8; /* Interrupt Enable Register */sfr IE2 = 0xAF; /* Interrupt Enable 2 Register *//*** Interrupt Registers Bits Definition*//** IE */#define GLOBAL_IE_EA (0x80)#define UART_IE_ES(0x10) /* Enable UART interrupt request *//** IE2 */#define T2_IE2_ET2(0x04) /* Timer 2 interrupt enable *//*** Power Management Registers Definition*/sfr PCON = 0x87; /* Power Control *//*** UART Registers Definition*/sfr SCON = 0x98; /* Serial Control */sfr SBUF = 0x99; /* Serial Buffer *//*** UART Registers Bits Definition*//** SCON */#define UART_SCON_SM0 (0x80) /* UART - Serial Mode Selection Bit 0 */#define UART_SCON_SM1 (0x40) /* UART - Serial Mode Selection Bit 1 */#define UART_SCON_REN (0x10) /* UART - Receiver Enable */#define UART_SCON_TI (0x02) /* UART - Transmission Completion Interrupt */#define UART_SCON_RI (0x01) /* UART - Reception Completion Interrupt */sbit TI = SCON^1;sbit RI = SCON^0;/*** Timer 2 Registers Definition*/sfr T2L= 0xD7; /* Timer 2 Counter Low Register */sfr T2H= 0xD6; /* Timer 2 Counter High Register */sfr AUXR = 0x8E; /* Auxiliary Register *//*** Timer 2 Registers Bits Definition*//** AUXR */#define T2_AUXR_T2R(0x10) /* Timer 2 - Run Control */#define T2_AUXR_T2CT (0x08) /* Timer 2 - Counter or Timer Selection */#define T2_AUXR_T2x12 (0x04) /* Timer 2 - Speed Control */#define UART_AUXR_S1ST2 (0x01) /* UART - Serial 1 (UART) Select Timer 2 Acts As Baud Rate Generator *//*** Port 1 Registers Definition*/sfr P1 = 0x90; /* Port 1 Register */typedef enum {FALSE = 0,TRUE = !FALSE} boolean;#define enableInterrupts(enable) if(enable) {\IE |= GLOBAL_IE_EA;\} else {\IE &= ~GLOBAL_IE_EA; \} #endif

timer2.h头文件：

#ifndef __STC15W204S_TIMER_2_H#define __STC15W204S_TIMER_2_H#include "stc15w204s.h"typedef enum {TIMER2_PRESCALER_DIVIDED_BY_1 = 0,TIMER2_PRESCALER_DIVIDED_BY_12 = 12} Timer2Prescaler;typedef struct {void (*asTimer)(boolean);void (*setCounter)(unsigned int);void (*setTimer)(unsigned int);unsigned int (*getCounter)();unsigned int (*getTimer)();void (*setPrescaler)(Timer2Prescaler);void (*start)(boolean);void (*enableInterrupt)(boolean);} Timer2;extern Timer2 timer2;/*** First call to this function to initialize* the <code>timer2</code> variable.*/void Timer2Constructor();#endif

timer2.c文件：

#include "timer2.h"Timer2 timer2;/*** If true, timer 2 acts as timer,* otherwise it acts as counter.*/static void asTimer(boolean isTimer) {if(isTimer) {AUXR &= ~T2_AUXR_T2CT;} else {AUXR |= T2_AUXR_T2CT;}}/*** Set the initial value of the counter* or the timer 2.*/static void setCounter(unsigned int counter) {T2H = (counter) >> 8;T2L = (counter) & 0xff;}/*** Return the value of the counter* or the timer 2.*/static unsigned int getCounter() {unsigned int counter;counter = T2H;counter = (counter << 8) | T2L;return counter;}/*** Set the prescaler of the timer 2.*/static void setPrescaler(Timer2Prescaler prescaler) {switch(prescaler) {case TIMER2_PRESCALER_DIVIDED_BY_1:AUXR |= T2_AUXR_T2x12;break;case TIMER2_PRESCALER_DIVIDED_BY_12:AUXR &= ~T2_AUXR_T2x12;break;}}/*** If true, start the timer 2 to run,* othewise, stop.*/static void start(boolean start) {if(start) {AUXR |= T2_AUXR_T2R;} else {AUXR &= ~T2_AUXR_T2R;}}/*** If true, enable timer 2 overflow* interrupt request, othewise, disable.*/static void enableInterrupt(boolean enable) {if (enable) {IE2 |= T2_IE2_ET2;} else {IE2 &= ~T2_IE2_ET2;}}void Timer2Constructor() {timer2.asTimer = &asTimer;timer2.setCounter = &setCounter;timer2.getCounter = &getCounter;timer2.setTimer = &setCounter;timer2.getTimer = &getCounter;timer2.setPrescaler = &setPrescaler;timer2.start = &start;timer2.enableInterrupt = &enableInterrupt;}

uart.h头文件：

#ifndef __STC15W204S_UART_H#define __STC15W204S_UART_H#include "stc15w204s.h"typedef enum {UART_MODE_0 = ((unsigned char)0x00), // NO TEST!UART_MODE_1 = ((unsigned char)0x40),UART_MODE_2 = ((unsigned char)0x80), // NO TEST!UART_MODE_3 = ((unsigned char)0xC0) // NO TEST!} UartMode;typedef enum {// In the STC15W204S SOP16, only Timer 2 is available for UART.UART_BAUD_RATE_GENERATOR_TIMER_2 = ((unsigned char)0x01)} UartBaudRateGenerator;typedef enum {UART_BAUD_RATE_1200= (1200),UART_BAUD_RATE_2400= (2400),UART_BAUD_RATE_4800= (4800),UART_BAUD_RATE_9600= (9600),UART_BAUD_RATE_14400 = (14400),UART_BAUD_RATE_19200 = (19200),UART_BAUD_RATE_28800 = (28800)} UartBaudRate;typedef enum {UART_INTERRUPT_FLAG_TX = ((unsigned char)0x02),UART_INTERRUPT_FLAG_RX = ((unsigned char)0x01)} UartInterruptFlag;typedef struct {void (*setMode)(UartMode);void (*selectBaudRateGenerator)(UartBaudRateGenerator);void (*setBaudRate)(UartBaudRate);void (*enableReceiver)(boolean);void (*clearInterruptFlag)(UartInterruptFlag);void (*enableInterrupt)(boolean);} Uart;extern Uart uart;/*** First call to this function to initialize* the <code>uart</code> variable.*/void UartConstructor();#endif

uart.c文件：

#include "uart.h"Uart uart;/*** Set the mode of the UART.*/static void setMode(UartMode mode) {switch(mode) {case UART_MODE_0:SCON &= ~(UART_SCON_SM0 | UART_SCON_SM1);break;case UART_MODE_1:SCON &= ~UART_SCON_SM0;SCON |= UART_SCON_SM1;break;case UART_MODE_2:SCON |= UART_SCON_SM0;SCON &= ~UART_SCON_SM1;break;case UART_MODE_3:SCON |= (UART_SCON_SM0 | UART_SCON_SM1);break;}}/*** Set the baud rate generator for the UART communication.* Be careful, in the STC15W204S SOP16, Timer 1 is unavailable,* only the Timer 2 can be use as the UART baud rate generator.* So you must configure the Timer 2 for the UART.*/static void selectBaudRateGenerator(UartBaudRateGenerator baudRateGenerator) {switch(baudRateGenerator) {case UART_BAUD_RATE_GENERATOR_TIMER_2:default:AUXR |= UART_AUXR_S1ST2; // FORCE USE!break;}}/*** Set the baud rate of the UART communication.* Be careful, in the STC15W204S SOP16, Timer 1 is unavailable,* only the Timer 2 can be use as the UART baud rate generator.* So you must configure the Timer 2 for the UART.*/static void setBaudRate(UartBaudRate baudRate) {unsigned int counter;if((AUXR & T2_AUXR_T2x12) == T2_AUXR_T2x12) {counter = 65536 - (SYSTEM_CLOCK / baudRate / 4);} else {counter = 65536 - (SYSTEM_CLOCK / baudRate / 12 / 4);}T2H = (counter) >> 8;T2L = (counter) & 0xff;}/*** If true, enable the receiver,* otherwise, disable.*/static void enableReceiver(boolean enable) {if(enable) {SCON |= UART_SCON_REN;} else {SCON &= ~UART_SCON_REN;}}/*** Clears the UART interrupt request flag.*/static void clearInterruptFlag(UartInterruptFlag flag) {switch(flag) {case UART_INTERRUPT_FLAG_TX:SCON &= ~UART_SCON_TI;break;case UART_INTERRUPT_FLAG_RX:SCON &= ~UART_SCON_RI;break;}}/*** If true, enable UART interrupt request,* othewise, disable.*/static void enableInterrupt(boolean enable) {if (enable) {IE |= UART_IE_ES;} else {IE &= ~UART_IE_ES;}}void UartConstructor() {uart.setMode = &setMode;uart.selectBaudRateGenerator = &selectBaudRateGenerator;uart.setBaudRate = &setBaudRate;uart.enableReceiver = &enableReceiver;uart.clearInterruptFlag = &clearInterruptFlag;uart.enableInterrupt = &enableInterrupt;}

main.c文件：

/*** STC15W204S-35I SOP16* UART - Mode 1: 1 start bit, 8 bit data, 1 stop bit*/#include "timer2.h"#include "uart.h"sbit LED = P1^1;void main() {UartConstructor();Timer2Constructor();// Timer 2 use for UART baud rate generatortimer2.asTimer(TRUE);timer2.setPrescaler(TIMER2_PRESCALER_DIVIDED_BY_1);timer2.start(TRUE);uart.setMode(UART_MODE_1);uart.selectBaudRateGenerator(UART_BAUD_RATE_GENERATOR_TIMER_2);uart.setBaudRate(UART_BAUD_RATE_28800);uart.enableReceiver(TRUE);uart.clearInterruptFlag(UART_INTERRUPT_FLAG_TX);uart.clearInterruptFlag(UART_INTERRUPT_FLAG_RX);timer2.enableInterrupt(FALSE);uart.enableInterrupt(TRUE);enableInterrupts(TRUE);while(1) {}}void uartInterruptService() interrupt 4 {unsigned char buffer;if(RI) {RI = 0;buffer = SBUF; // GetSBUF = buffer; // SetLED = !LED;}if(TI) {TI = 0;}}

下载、测试

呃，9600 的通信速度，数据出现丢失！不过可能和硬件有关，因为我使用了杜邦线，可能是导线过长导致的！

参考

宏晶科技 STC - STC15 系列单片机器件手册