STC89c51RC 在11.0592M晶振下设置115200的波特率

使用GPRS模块，模块固定波特率115200， 手头有现成的STC89c51RC，一般51不能达到115200，查找资料使用下面的配置可以实现115200的波特率， 已经测试过OK。


//#include "reg51.h"
#include "intrins.h"
#include "STC89C5xRC.h"

typedef unsigned char BYTE;
typedef unsigned int WORD;

#define FOSC 18432000L //System frequency
#define BAUD 9600 //UART baudrate

/*Define UART parity mode*/
#define NONE_PARITY 0 //None parity
#define ODD_PARITY 1 //Odd parity
#define EVEN_PARITY 2 //Even parity
#define MARK_PARITY 3 //Mark parity
#define SPACE_PARITY 4 //Space parity

#define PARITYBIT EVEN_PARITY //Testing even parity

sbit bit9 = P2^2; //P2.2 show UART data bit9
bit busy;

void SendData(BYTE dat);
void SendString(char *s);


void init()//串口初始化
{
SCON=0x50; //SCON:串行口工作方式1, 8-bit UART,允许串行接收位(REN=1)
TL2=RCAP2L=250;//或253
TH2=RCAP2H=255;
T2CON=0x34;//

EA=1; //开总中断
ES=1; //开串口中断

}

void main()
{
/*
#if (PARITYBIT == NONE_PARITY)
SCON = 0x50; //8-bit variable UART
#elif (PARITYBIT == ODD_PARITY) || (PARITYBIT == EVEN_PARITY) || (PARITYBIT == MARK_PARITY)
SCON = 0xda; //9-bit variable UART, parity bit initial to 1
#elif (PARITYBIT == SPACE_PARITY)
SCON = 0xd2; //9-bit variable UART, parity bit initial to 0
#endif

TMOD = 0x20; //Set Timer1 as 8-bit auto reload mode
TH1 = TL1 = -(FOSC/12/32/BAUD); //Set auto-reload vaule
TR1 = 1; //Timer1 start run
ES = 1; //Enable UART interrupt
EA = 1; //Open master interrupt switch
*/

init();
SendString("STC89-90xxrnUart Test !rn");
while(1);
}

/*----------------------------
UART interrupt service routine
----------------------------*/
void Uart_Isr() interrupt 4 using 1
{
if (RI)
{
RI = 0; //Clear receive interrupt flag
P0 = SBUF; //P0 show UART data
bit9 = RB8; //P2.2 show parity bit
}
if (TI)
{
TI = 0; //Clear transmit interrupt flag
busy = 0; //Clear transmit busy flag
}
}

/*----------------------------
Send a byte data to UART
Input: dat (data to be sent)
Output:None
----------------------------*/
void SendData(BYTE dat)
{
while (busy); //Wait for the completion of the previous data is sent
ACC = dat; //Calculate the even parity bit P (PSW.0)
if (P) //Set the parity bit according to P
{
#if (PARITYBIT == ODD_PARITY)
TB8 = 0; //Set parity bit to 0
#elif (PARITYBIT == EVEN_PARITY)
TB8 = 1; //Set parity bit to 1
#endif
}
else
{
#if (PARITYBIT == ODD_PARITY)
TB8 = 1; //Set parity bit to 1
#elif (PARITYBIT == EVEN_PARITY)
TB8 = 0; //Set parity bit to 0
#endif
}
busy = 1;
SBUF = ACC; //Send data to UART buffer
}

/*----------------------------
Send a string to UART
Input: s (address of string)
Output:None
----------------------------*/
void SendString(char *s)
{
while (*s) //Check the end of the string
{
SendData(*s++); //Send current char and increment string ptr
}
}

================================================
STC89C5xRC.h

/* After is STC additional SFR */

/* sfr AUXR = 0x8e; */
/* sfr AUXR1 = 0xa2; */
/* sfr IPH = 0xb7; */

sfr P4 = 0xe8;
sbit P43 = P4^3;
sbit P42 = P4^2;
sbit P41 = P4^1;
sbit P40 = P4^0;

sfr XICON = 0xc0;

sfr WDT_CONTR = 0xe1;

sfr ISP_DATA = 0xe2;
sfr ISP_ADDRH = 0xe3;
sfr ISP_ADDRL = 0xe4;
sfr ISP_CMD = 0xe5;
sfr ISP_TRIG = 0xe6;
sfr ISP_CONTR = 0xe7;

/* Above is STC additional SFR */

/*--------------------------------------------------------------------------
REG51F.H

Header file for 8xC31/51, 80C51Fx, 80C51Rx+
Copyright (c) 1988-1999 Keil Elektronik GmbH and Keil Software, Inc.
All rights reserved.

Modification according to DataSheet from April 1999
- SFR's AUXR and AUXR1 added for 80C51Rx+ derivatives
--------------------------------------------------------------------------*/

/* BYTE Registers */
sfr P0 = 0x80;
sfr P1 = 0x90;
sfr P2 = 0xA0;
sfr P3 = 0xB0;
sfr PSW = 0xD0;
sfr ACC = 0xE0;
sfr B = 0xF0;
sfr SP = 0x81;
sfr DPL = 0x82;
sfr DPH = 0x83;
sfr PCON = 0x87;
sfr TCON = 0x88;
sfr TMOD = 0x89;
sfr TL0 = 0x8A;
sfr TL1 = 0x8B;
sfr TH0 = 0x8C;
sfr TH1 = 0x8D;
sfr IE = 0xA8;
sfr IP = 0xB8;
sfr SCON = 0x98;
sfr SBUF = 0x99;

/* 80C51Fx/Rx Extensions */
sfr AUXR = 0x8E;
sfr AUXR1 = 0xA2;
sfr SADDR = 0xA9;
sfr IPH = 0xB7;
sfr SADEN = 0xB9;
sfr T2CON = 0xC8;
sfr T2MOD = 0xC9;
sfr RCAP2L = 0xCA;
sfr RCAP2H = 0xCB;
sfr TL2 = 0xCC;
sfr TH2 = 0xCD;

/* PCA SFR
sfr CCON = 0xD8;
sfr CMOD = 0xD9;
sfr CCAPM0 = 0xDA;
sfr CCAPM1 = 0xDB;
sfr CCAPM2 = 0xDC;
sfr CCAPM3 = 0xDD;
sfr CCAPM4 = 0xDE;
sfr CL = 0xE9;
sfr CCAP0L = 0xEA;
sfr CCAP1L = 0xEB;
sfr CCAP2L = 0xEC;
sfr CCAP3L = 0xED;
sfr CCAP4L = 0xEE;
sfr CH = 0xF9;
sfr CCAP0H = 0xFA;
sfr CCAP1H = 0xFB;
sfr CCAP2H = 0xFC;
sfr CCAP3H = 0xFD;
sfr CCAP4H = 0xFE;
*/

/* BIT Registers */
/* PSW */
sbit CY = PSW^7;
sbit AC = PSW^6;
sbit F0 = PSW^5;
sbit RS1 = PSW^4;
sbit RS0 = PSW^3;
sbit OV = PSW^2;
sbit P = PSW^0;

/* TCON */
sbit TF1 = TCON^7;
sbit TR1 = TCON^6;
sbit TF0 = TCON^5;
sbit TR0 = TCON^4;
sbit IE1 = TCON^3;
sbit IT1 = TCON^2;
sbit IE0 = TCON^1;
sbit IT0 = TCON^0;

/* IE */
sbit EA = IE^7;
sbit EC = IE^6;
sbit ET2 = IE^5;
sbit ES = IE^4;
sbit ET1 = IE^3;
sbit EX1 = IE^2;
sbit ET0 = IE^1;
sbit EX0 = IE^0;

/* IP */
/* sbit PPC = IP^6;*/
sbit PT2 = IP^5;
sbit PS = IP^4;
sbit PT1 = IP^3;
sbit PX1 = IP^2;
sbit PT0 = IP^1;
sbit PX0 = IP^0;

/* P3 */
sbit RD = P3^7;
sbit WR = P3^6;
sbit T1 = P3^5;
sbit T0 = P3^4;
sbit INT1 = P3^3;
sbit INT0 = P3^2;
sbit TXD = P3^1;
sbit RXD = P3^0;

/* SCON */
sbit SM0 = SCON^7; // alternatively "FE"
sbit FE = SCON^7;
sbit SM1 = SCON^6;
sbit SM2 = SCON^5;
sbit REN = SCON^4;
sbit TB8 = SCON^3;
sbit RB8 = SCON^2;
sbit TI = SCON^1;
sbit RI = SCON^0;

/* P1 */
/* PCA
sbit CEX4 = P1^7;
sbit CEX3 = P1^6;
sbit CEX2 = P1^5;
sbit CEX1 = P1^4;
sbit CEX0 = P1^3;
sbit ECI = P1^2;
*/

sbit T2EX = P1^1;
sbit T2 = P1^0;

/* T2CON */
sbit TF2 = T2CON^7;
sbit EXF2 = T2CON^6;
sbit RCLK = T2CON^5;
sbit TCLK = T2CON^4;
sbit EXEN2 = T2CON^3;
sbit TR2 = T2CON^2;
sbit C_T2 = T2CON^1;
sbit CP_RL2= T2CON^0;

/* CCON */
/* PCA
sbit CF = CCON^7;
sbit CR = CCON^6;

sbit CCF4 = CCON^4;
sbit CCF3 = CCON^3;
sbit CCF2 = CCON^2;
sbit CCF1 = CCON^1;
sbit CCF0 = CCON^0;
*/
================================================
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STC的URAT在6T模式下工作的问题

测试程序使用小强开发板光盘中的《串口收发 测试程序[深圳伟嵌科技].C》修改，主要是定时器，使用了定时器2作为波特率发生器。
晶振：11.0592M
通过计算可得知
当 TL2=RCAP2L=250; 时
12T模式下波特率57600,6T模式下波特率115200。
当 TL2=RCAP2L=253; 时
12T模式下波特率115200。

使用STC-ISP中的串口调试助手分别测试三种模式
A:6T,TL2=250,波特率115200
B:12T,TL2=250,波特率57600
C:12T,TL2=253,波特率115200

void init()//串口初始化
{
SCON=0x50; //SCON:串行口工作方式1, 8-bit UART,允许串行接收位(REN=1)
TL2=RCAP2L=250;//或253
TH2=RCAP2H=255;
T2CON=0x34;//

EA=1; //开总中断
ES=1; //开串口中断

}

测试结果：
A:会丢失第n*3个字符（n为自然数）
B、C正常，自动发送一千多个字符，一个不落收到
从整个程序分析，流程是串口初始化并延时1ms，进入死循环等待中断。
接收中断发送后，清中断标志，把串口SBUF复制给P0口和中间变量a，把a放入receive数组，再把receive数组的内容逐个送到SBUF让串口发送，很简单很直接，应该没有问题。
又测试了6T,TL2=244,波特率57600的模式，丢第n*5个字符。
所以，应该是STC的串口在6T模式下不能可靠工作，或者不能与其它器件很好地配合。