TI官方非常贴心的为我们准备了28335的sci口例程，使用串口芯片232完全没有问题。例程主程序如下：
#include "DSP2833x_Device.h" // DSP2833x Headerfile Include File
#include "DSP2833x_Examples.h" // DSP2833x Examples Include File
// Prototype statements for functions found within this file.
void scic_echoback_init(void);
void scic_fifo_init(void);
void scic_xmit(int a);
void scic_msg(char *msg);
// Global counts used in this example
Uint16 LoopCount;
Uint16 ErrorCount;
void main(void)
{
Uint16 ReceivedChar;
char *msg;
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2833x_SysCtrl.c file.
InitSysCtrl();
// Step 2. Initalize GPIO:
// This example function is found in the DSP2833x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio(); Skipped for this example
// For this example, only init the pins for the SCI-A port.
// This function is found in the DSP2833x_Sci.c file.
InitScicGpio();
InitXintf16Gpio();
// Step 3. Clear all interrupts and initialize PIE vector table:
// Disable CPU interrupts
DINT;
// Initialize PIE control registers to their default state.
// The default state is all PIE interrupts disabled and flags
// are cleared.
// This function is found in the DSP2833x_PieCtrl.c file.
InitPieCtrl();
// Disable CPU interrupts and clear all CPU interrupt flags:
IER = 0x0000;
IFR = 0x0000;
// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
// This will populate the entire table, even if the interrupt
// is not used in this example. This is useful for debug purposes.
// The shell ISR routines are found in DSP2833x_DefaultIsr.c.
// This function is found in DSP2833x_PieVect.c.
InitPieVectTable();
// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP2833x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
// Step 5. User specific code:
LoopCount = 0;
ErrorCount = 0;
scic_fifo_init(); // Initialize the SCI FIFO
scic_echoback_init(); // Initalize SCI for echoback
msg = "\r\n\n\nHello World!\0";
scic_msg(msg);
msg = "\r\nYou will enter a character, and the DSP will echo it back! \n\0";
scic_msg(msg);
for(;;)
{
msg = "\r\nEnter a character: \0";
scic_msg(msg);
// Wait for inc character
while(ScicRegs.SCIFFRX.bit.RXFFST == 0) {} // wait for XRDY =1 for empty state
msg = " You sent: \0";
scic_msg(msg);
// Get all character
do
{
ReceivedChar = ScicRegs.SCIRXBUF.all;
// Echo character back
scic_xmit(ReceivedChar);
}while(ScicRegs.SCIFFRX.bit.RXFFST != 0);
LoopCount++;
}
}
// Test 1,SCIA DLB, 8-bit word, baud rate 0x000F, default, 1 STOP bit, no parity
void scic_echoback_init()
{
// Note: Clocks were turned on to the SCIA peripheral
// in the InitSysCtrl() function
ScicRegs.SCICCR.all =0x0007; // 1 stop bit, No loopback
// No parity,8 char bits,
// async mode, idle-line protocol
ScicRegs.SCICTL1.all =0x0003; // enable TX, RX, internal SCICLK,
// Disable RX ERR, SLEEP, TXWAKE
ScicRegs.SCICTL2.all =0x0003;
ScicRegs.SCICTL2.bit.TXINTENA = 1;
ScicRegs.SCICTL2.bit.RXBKINTENA =1;
#if (CPU_FRQ_150MHZ)
ScicRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 37.5MHz.
ScicRegs.SCILBAUD =0x00E7;
#endif
#if (CPU_FRQ_100MHZ)
ScicRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 20MHz.
ScicRegs.SCILBAUD =0x0044;
#endif
ScicRegs.SCICTL1.all =0x0023; // Relinquish SCI from Reset
}
// Transmit a character from the SCI
void scic_xmit(int a)
{
while (ScicRegs.SCIFFTX.bit.TXFFST != 0) {}
ScicRegs.SCITXBUF=a;
}
void scic_msg(char * msg)
{
int i;
i = 0;
while(msg != '\0')
{
scic_xmit(msg);
i++;
}
}
// Initalize the SCI FIFO
void scic_fifo_init()
{
ScicRegs.SCIFFTX.all=0xE040;
ScicRegs.SCIFFRX.all=0x204f;
ScicRegs.SCIFFCT.all=0x0;
}
//===========================================================================
// No more.
//===========================================================================
这个程序使用在232串口调试时完全没有问题。
现在因为需要改用485通讯。485通讯多了发送和接受使能控制功能。因为使用一问一答方式通讯，所以将485的两个控制口并在一起使用一个IO控制。
修改程序如下：
#include "DSP2833x_Device.h" // DSP2833x Headerfile Include File
#include "DSP2833x_Examples.h" // DSP2833x Examples Include File
#define CON_485 GpioDataRegs.GPCDAT.bit.GPIO70
// Prototype statements for functions found within this file.
void scic_echoback_init(void);
void scic_fifo_init(void);
void scic_xmit(int a);
void scic_msg(char *msg);
// Global counts used in this example
Uint16 LoopCount;
Uint16 ErrorCount;
void main(void)
{
Uint16 ReceivedChar;
char *msg;
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2833x_SysCtrl.c file.
InitSysCtrl();
// Step 2. Initalize GPIO:
// This example function is found in the DSP2833x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio(); Skipped for this example
// For this example, only init the pins for the SCI-A port.
// This function is found in the DSP2833x_Sci.c file.
InitScicGpio();
InitXintf16Gpio();
// Step 3. Clear all interrupts and initialize PIE vector table:
// Disable CPU interrupts
DINT;
// Initialize PIE control registers to their default state.
// The default state is all PIE interrupts disabled and flags
// are cleared.
// This function is found in the DSP2833x_PieCtrl.c file.
InitPieCtrl();
// Disable CPU interrupts and clear all CPU interrupt flags:
IER = 0x0000;
IFR = 0x0000;
// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
// This will populate the entire table, even if the interrupt
// is not used in this example. This is useful for debug purposes.
// The shell ISR routines are found in DSP2833x_DefaultIsr.c.
// This function is found in DSP2833x_PieVect.c.
InitPieVectTable();
// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP2833x_InitPeripherals.c
// InitPeripherals(); // Not required for this example
// Step 5. User specific code:
LoopCount = 0;
ErrorCount = 0;
scic_fifo_init(); // Initialize the SCI FIFO
scic_echoback_init(); // Initalize SCI for echoback
msg = "\r\n\n\nHello World!\0";
scic_msg(msg);
msg = "\r\nYou will enter a character, and the DSP will echo it back! \n\0";
scic_msg(msg);
for(;;)
{
msg = "\r\nEnter a character: \0";
scic_msg(msg);
// Wait for inc character
while(ScicRegs.SCIFFRX.bit.RXFFST == 0) {} // wait for XRDY =1 for empty state
msg = " You sent: \0";
scic_msg(msg);
// Get all character
do
{
ReceivedChar = ScicRegs.SCIRXBUF.all;
// Echo character back
scic_xmit(ReceivedChar);
}while(ScicRegs.SCIFFRX.bit.RXFFST != 0);
LoopCount++;
}
}
// Test 1,SCIA DLB, 8-bit word, baud rate 0x000F, default, 1 STOP bit, no parity
void scic_echoback_init()
{
// Note: Clocks were turned on to the SCIA peripheral
// in the InitSysCtrl() function
ScicRegs.SCICCR.all =0x0007; // 1 stop bit, No loopback
// No parity,8 char bits,
// async mode, idle-line protocol
ScicRegs.SCICTL1.all =0x0003; // enable TX, RX, internal SCICLK,
// Disable RX ERR, SLEEP, TXWAKE
ScicRegs.SCICTL2.all =0x0003;
ScicRegs.SCICTL2.bit.TXINTENA = 1;
ScicRegs.SCICTL2.bit.RXBKINTENA =1;
#if (CPU_FRQ_150MHZ)
ScicRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 37.5MHz.
ScicRegs.SCILBAUD =0x00E7;
#endif
#if (CPU_FRQ_100MHZ)
ScicRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 20MHz.
ScicRegs.SCILBAUD =0x0044;
#endif
ScicRegs.SCICTL1.all =0x0023; // Relinquish SCI from Reset
}
// Transmit a character from the SCI
void scic_xmit(int a)
{
while (ScicRegs.SCIFFTX.bit.TXFFST != 0) {}
ScicRegs.SCITXBUF=a;
}
void scic_msg(char * msg)
{
int i;
CON_485=1;//打开发送功能 使能发送485引脚 i = 0;
while(msg != '\0')
{
scic_xmit(msg);
i++;
}
CON_485=0;//关闭发送功能，使能接受功能}
// Initalize the SCI FIFO
void scic_fifo_init()
{
ScicRegs.SCIFFTX.all=0xE040;
ScicRegs.SCIFFRX.all=0x204f;
ScicRegs.SCIFFCT.all=0x0;
EALLOW;
GpioCtrlRegs.GPCMUX1.bit.GPIO70 = 0; //485_CON
GpioCtrlRegs.GPCDIR.bit.GPIO70 = 1;
EDIS;
}
//===========================================================================
// No more.
//===========================================================================
只是增加了485的控制功能，但是现在出现SCIRXST中的PE、BRKDT、RXERROR都置1的错误。
发送功能正常。当把上面蓝色的字CON_485=1注释掉以后，接受就正常了，但是这时因为没有使能发送所以又无法发送了。
这是哪里的原因呢？
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