TMS320F280049C: Using sci's fifo to send serial data is normal, but the reception is abnormal

Hi Team,

#include "driverlib.h"
#include "device.h"
 
#ifdef _FLASH
// These are defined by the linker (see device linker command file)
extern uint16_t RamfuncsLoadStart;
extern uint16_t RamfuncsLoadSize;
extern uint16_t RamfuncsRunStart;
#endif
 
//
// Defines
//
// Define AUTOBAUD to use the autobaud lock feature
//#define AUTOBAUD
 
//
// Globals
//
uint16_t counter = 0;
unsigned char *msg;
//
// Function Prototypes
//
__interrupt void sciaTxISR(void);
__interrupt void sciaRxISR(void);
 
//
// Main
//
void main(void)
{
    //
    // Configure PLL, disable WD, enable peripheral clocks.
    //
    Device_init();
 
    //
    // Disable pin locks and enable internal pullups.
    //
    Device_initGPIO();
 
    //
    // GPIO28 is the SCI Rx pin.
    //
    GPIO_setMasterCore(DEVICE_GPIO_PIN_SCIRXDA, GPIO_CORE_CPU1);            //选择指定GPIO28引脚，主核心为CPU1
    GPIO_setPinConfig(DEVICE_GPIO_CFG_SCIRXDA);                             //GPIO28配置为SCI的 RX接收引脚
    GPIO_setDirectionMode(DEVICE_GPIO_PIN_SCIRXDA, GPIO_DIR_MODE_IN);       //GPIO28引脚 设置为输入
    GPIO_setPadConfig(DEVICE_GPIO_PIN_SCIRXDA, GPIO_PIN_TYPE_STD);          //GPIO28引脚引脚类型 为浮动输入
    GPIO_setQualificationMode(DEVICE_GPIO_PIN_SCIRXDA, GPIO_QUAL_ASYNC);    //GPIO28参数条件模式 为关闭同步
 
    //
    // GPIO29 is the SCI Tx pin.
    //
    GPIO_setMasterCore(DEVICE_GPIO_PIN_SCITXDA, GPIO_CORE_CPU1);            //选择指定GPIO29引脚，主核心为CPU1
    GPIO_setPinConfig(DEVICE_GPIO_CFG_SCITXDA);                             //GPIO29配置为SCI的 TX发送引脚
    GPIO_setDirectionMode(DEVICE_GPIO_PIN_SCITXDA, GPIO_DIR_MODE_OUT);      //GPIO29引脚 设置为输出
    GPIO_setPadConfig(DEVICE_GPIO_PIN_SCITXDA, GPIO_PIN_TYPE_STD);          //GPIO29引脚引脚类型 为推挽输出
    GPIO_setQualificationMode(DEVICE_GPIO_PIN_SCITXDA, GPIO_QUAL_ASYNC);    //GPIO29参数条件模式 为关闭同步
 
 
    //
    // Disable global interrupts.
    //
    DINT; //禁用全局中断
 
    //
    // Initialize interrupt controller and vector table.
    //
    Interrupt_initModule();                                                  //初始化PIE并清除PIE寄存器
    Interrupt_initVectorTable();                                             //用指向shell中断的指针初始化PIE向量表ISR服务程序
    IER = 0x0000;                                                            //中断使能寄存器 置0
    IFR = 0x0000;                                                            //中断标志寄存器 置0
 
 
    //
    // Map the ISR to the wake interrupt.
    //
    Interrupt_register(INT_SCIA_TX, sciaTxISR);//将中断函数与中断向量表映射
    Interrupt_register(INT_SCIA_RX, sciaRxISR);
 
    //
    // Initialize SCIA and its FIFO.
    //
    SCI_performSoftwareReset(SCIA_BASE);//软件重置初始化SCIA
 
    //
    // Configure SCIA for echoback.
    //
    SCI_setConfig(SCIA_BASE, 25000000, 9600, (SCI_CONFIG_WLEN_8 |
                                             SCI_CONFIG_STOP_ONE |
                                             SCI_CONFIG_PAR_NONE));//初始化
    SCI_resetChannels(SCIA_BASE);//通道重置
    SCI_clearInterruptStatus(SCIA_BASE, SCI_INT_TXFF | SCI_INT_RXFF);//清除接收、发送中断寄存器标志位
    SCI_enableFIFO(SCIA_BASE);//使能FIFO
    SCI_enableModule(SCIA_BASE);//使能接收、发送、重启SCI
    SCI_performSoftwareReset(SCIA_BASE);//软件重置SCIA
 
 
    //
    // Set the transmit FIFO level to 0 and the receive FIFO level to 2.
    // Enable the TXFF and RXFF interrupts.
    //
    SCI_setFIFOInterruptLevel(SCIA_BASE, SCI_FIFO_TX0, SCI_FIFO_RX3);//FIFO深度设置
    SCI_enableInterrupt(SCIA_BASE, SCI_INT_TXFF | SCI_INT_RXFF);//使能接收、发送中断寄存器标志位
 
    //
    // Send starting message.
    //
    msg = "\r\n\n\nHello World!\0";
    SCI_writeCharArray(SCIA_BASE, (uint16_t*)msg, 17);
    msg = "\r\nYou will enter a character, and the DSP will echo it back!\0";
    SCI_writeCharArray(SCIA_BASE, (uint16_t*)msg, 61);
 
    //
    // Clear the SCI interrupts before enabling them.
    //
    SCI_clearInterruptStatus(SCIA_BASE, SCI_INT_TXFF | SCI_INT_RXFF);//清除接收、发送中断寄存器标志位
 
    //
    // Enable the interrupts in the PIE: Group 9 interrupts 1 & 2.
    //
    Interrupt_enable(INT_SCIA_RX);//使能外设中断RX、TX
    Interrupt_enable(INT_SCIA_TX);
    Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP9);//9号中断向量组的9.1、9.2号
 
    //
    // Enable global interrupts.
    //
    EINT;
 
    for(;;)
    {
    }
}
 
//
// sciaTxISR - Disable the TXFF interrupt and print message asking
//             for two characters.
 
__interrupt void
sciaTxISR(void)
{
    //
    // Disable the TXRDY interrupt.
    //
    SCI_disableInterrupt(SCIA_BASE, SCI_INT_TXFF);
 
 
    msg = "\r\nEnter two characters: \0";
    SCI_writeCharArray(SCIA_BASE, (uint16_t*)msg, 25);
    //
    // Acknowledge the PIE interrupt.
    //
    Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP9);
}
//
// sciaRxISR - Read two characters from the RXBUF and echo them back.
//
__interrupt void
sciaRxISR(void)
{
    uint16_t receivedChar1, receivedChar2, receivedChar3;//receivedChar4;
    //
    // Enable the TXFF interrupt again.
    //
    SCI_enableInterrupt(SCIA_BASE, SCI_INT_TXFF);
    //
    // Read two characters from the FIFO.                      //读取三次sci
    //
    receivedChar1 = SCI_readCharBlockingFIFO(SCIA_BASE);
    receivedChar2 = SCI_readCharBlockingFIFO(SCIA_BASE);
    receivedChar3 = SCI_readCharBlockingFIFO(SCIA_BASE);
    //
    // Echo back the two characters.
    //
    msg = "  You sent: \0";
    SCI_writeCharArray(SCIA_BASE, (uint16_t*)msg, 13);
    SCI_writeCharBlockingFIFO(SCIA_BASE, receivedChar1);         //发送三次读取到的数据
    SCI_writeCharBlockingFIFO(SCIA_BASE, receivedChar2);
    SCI_writeCharBlockingFIFO(SCIA_BASE, receivedChar3);
    //
    // Clear the SCI RXFF interrupt and acknowledge the PIE interrupt.
    //
    SCI_clearInterruptStatus(SCIA_BASE, SCI_INT_RXFF);
    Interrupt_clearACKGroup(INTERRUPT_ACK_GROUP9);
    counter++;
}
//
// End of File
//

1. The above is referring to the demo to send and receive FIFO data through SCIA. It can only be sent, but no data can be received. What is the reason?

2. How does FIFO transmission realize 485 flow control?

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Thanks & Regards

Yale