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分享C8051串口通信为什么会自动发送上一个收到的字符
我用的是C8051，通过串口往单片机里写数据，但是接受第二个字符时会自动发送前面接收到的字符。
接收字符用的是getchar();语句。
求大神帮助！！！
接收字符用的是getchar();语句。
求大神帮助！！！
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kunpeng08 2013-10-15
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没有，短了的话发出去它应该立马就收到字符了的，但是我这个是getchar();运行后才收到上一个发送的字符，而且此时串口调试软件没发东西
dceacho 2013-10-15
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不会是串口的2根线短路了吧
kunpeng08 2013-10-15
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我用的是KEIL软件
kunpeng08 2013-10-15
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while(flag_shakehand!=1)
{
RI0=0;
TI0=1;
getchar();
mode = SBUF0;
if(mode=='S')
{
mode = 'R';
RI0 = 1;
SBUF0 = mode;
TI0 = 0;
printf("%c%c",mode,&mode);
flag_shakehand=1;
break;
}
}
就比方里面的这段代码，if条件里面的代码页不执行，光执行getchar();就会发送数据了，我用的是keil getchar（）函数应该是内部的函数，我看不到里面的代码
kunpeng08 2013-10-15
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void SYSCLK_Init (void)
{
int i; // delay counter
OSCXCN = 0x67; // start external oscillator with
// 22.1184MHz crystal
for (i=0; i < 256; i++) ; // wait for oscillator to start
while (!(OSCXCN & 0x80)) ; // Wait for crystal osc. to settle
OSCICN = 0x88; // select external oscillator as SYSCLK
// source and enable missing clock
// detector
}
//-----------------------------------------------------------------------------
// PORT_Init
//-----------------------------------------------------------------------------
//
// Configure the Crossbar and GPIO ports
//
void PORT_Init (void)
{
XBR0 |= 0x04; // Enable UART0
#ifdef RSPI
XBR0 |= 0x02; // Enable SPI0
#endif
XBR2 |= 0x40; // Enable crossbar
XBR2 &= 0x7f; // Enable weak pull-ups
#ifdef RSPI
P0MDOUT &= ~0x40; // p_0.2 and p_0.3 oc output for SDA and SCL
#else
P0MDOUT &= ~0x0c; // p_0.2 and p_0.3 oc output for SDA and SCL
P0MDOUT &= ~0x20; // p_0.5 oc output for SDO input
#endif
P74OUT = 0xff; //enable P4 P5 P6 P7 as push-pull output
}
//-----------------------------------------------------------------------------
// UART0_Init
//-----------------------------------------------------------------------------
//
// Configure the UART0 using Timer1, for <baudrate> and 8-N-1.
//
void UART0_Init (void)
{
SCON0 = 0x50; // SCON0: mode 1, 8-bit UART, enable RX
TMOD = 0x20; // TMOD: timer 1, mode 2, 8-bit reload
TH1 = -(SYSCLK/BAUDRATE_UART0/16); // set Timer1 reload value for baudrate
TR1 = 1; // start Timer1
CKCON |= 0x10; // Timer1 uses SYSCLK as time base
PCON |= 0x80; // SMOD0 = 1 (disable baud rate divide-by-two)
TI0 = 1; // Indicate TX0 ready
REN0 = 1;
// EA =1;
// ES0 =1;
}
//
//-----------------------------------------------------------------------------
// SPI0_Init
//-----------------------------------------------------------------------------
//
// Configure SPI0 for 8-bit, 2MHz SCK, Master mode, polled operation, data
// sampled on 1st SCK rising edge.
//
void SPI0_Init (void)
{
SPI0CFG = 0xC7; // data sampled on 2nd SCK rising edge
// 8-bit data words
SPI0CN = 0x03; // Master mode; SPI enabled; flags
// cleared
SPI0CKR = SYSCLK/2/150000; // SPI clock <= 2MHz (limited by
// EEPROM spec.)
}
void main()
{
unsigned char ddf_i,code_flag,temp_00,temp_01,temp_04;
unsigned int flag_shakehand,flag_recv,i,y;
code_flag=0;
flag_recv=0;
temp_00=0;
temp_01=0;
temp_04=0;
ddf_i=0;
i=0;
y=0;
flag_shakehand=0;
// SEL=1;
// TRIG=1;
// SACLK=1;
WDTCN = 0xde; // disable watchdog timer
WDTCN = 0xad;
// SARESET=1;
//just for test
//c2codetest();
SYSCLK_Init (); // initialize oscillator
PORT_Init (); // initialize crossbar and GPIO
UART0_Init (); // initialize UART0
SPI0_Init();
//UART1_Init (); // initialize UART1
// transmit example
//sp120set ("appl:sin 5.0 khz,3.0 vpp,-2.0 v\n");
ddf_i=P0MDOUT;
//set P1 hz
P1MDOUT = 0x00; // enable P1 as open-drain outputs
P1 = 0xff;
//set P2 hz
P2MDOUT = 0x00; // enable P2 as open-drain outputs
P2 = 0xff;
//set P3 hz
P3MDOUT = 0x00; // enable P3 as open-drain outputs
P3 = 0xff;
//set P1.7 as digital input
P1MDIN |= 0x01;
//sp120set ("\n");
//sp120set ("\n");
//sp120set ("\n");
//sp120set ("resiter_test_start:\n");
//switch off all relay
P4=0x00;
P5=0x00;
P6=0x00;
P7=0x00;
while(1)
{
// flag_shakehand=1;
while(flag_shakehand!=1)
{
RI0=0;
TI0=1;
getchar();
// scanf("%c",SBUF0);
mode = SBUF0;
if(mode=='S')
{
mode = 'R';
RI0 = 1;
SBUF0 = mode;
TI0 = 0;
// putchar(mode);
printf("%c%c",mode,&mode);
flag_shakehand=1;
break;
}
}
while(flag_shakehand==1)
{
// getchar();
// mode = SBUF0;
// RI0 = 0;
// if(mode=='C')
// {
lsm303_m_test();
flag_shakehand=0;
y=0;
break;
// }
}
while(1)
{
getchar();
mode = SBUF0;
RI0 = 0;
switch(mode)
{
case 0x01:printf("%4f",avg_x);i=1;break;
case 0x02:printf("%4f",avg_y);i=2;break;
case 0x03:printf("%4f",avg_z);i=3;break;
case 0x04:printf("%4d",delt_x);i=4;break;
case 0x05:printf("%4d",delt_y);i=5;break;
case 0x06:printf("%4d",delt_z);i=6;break;
default:i=0;
}
while(i!=0)
{
getchar();
mode = SBUF0;
RI0 = 0;
if(mode=='r')
{
y++;
break;
}
if(mode=='n')
{
switch(i)
{
case 1:printf("%4f",avg_x);break;
case 2:printf("%4f",avg_y);break;
case 3:printf("%4f",avg_z);break;
case 4:printf("%4d",delt_x);break;
case 5:printf("%4d",delt_y);break;
case 6:printf("%4d",delt_z);break;
default:break;
}
}
}
if(y>=6)
break;
}
#if(0==BOARD_TYPE) //for SA9801
sa9801_test();
#elif(1==BOARD_TYPE) //for SD9886
sd9886_test();
#elif(2==BOARD_TYPE) //for SC8113
sc8113i2c();
#elif(3==BOARD_TYPE) //for SD7415 spi
sd7415spi();
#elif(4==BOARD_TYPE) //for SD7415 iic
sd7415i2c();
#elif(5==BOARD_TYPE) //for SC7312 iic
sc7313i2c();
#elif(6==BOARD_TYPE) //for SE33DE iic
se33de_test();
#elif(7==BOARD_TYPE) //for SE4200 spi
se4200spi();
#elif(8==BOARD_TYPE) //for SE4200 iic
se4200iic();
#elif(9==BOARD_TYPE) //for lsm303 iic
// if(mode=='1')
// lsm303_m_test();
// flag_recv=0;
#elif(10==BOARD_TYPE) //for lps331ap iic
lps331ap_test();
#elif(11==BOARD_TYPE) //for lps331ap iic
sc7a30_Rspi_test();
#endif
}
}
woshi_ziyu 2013-10-15
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贴下代码看看
天才2012 2013-10-15
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估计是你的逻辑有问题了！
palleexu 2013-10-15
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看你51的程序里面有没有将接收到的数据返回的语句？
of123 2013-10-15
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看一下底层代码，是否有发送的语句。
