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TMS320F28335项目开发记录10_28335之SCI模块

2019-07-13 15:43发布

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28335之SCI模块

1.介绍

    TMS320F28335内部有三个SCI模块，SCIA、SCIB、SCIC。     每一个SCI模块都有一个接收器和发送器，SCI的接收器和发送器各有一个16级的FIFO(First In First Out先入先出)队列，它们都还有自己独立的使能位和中断位；可以工作在半双工或全双工模式；     串行通信的三种方式：      

2.SCI深入

    A. GPIO的管脚对应如下:   SCIA对应GPIO28/29和GPIO35/36两组可选；   SCIB有四组管脚可以选择，分别是 O9/11,GPIO14/15,GPIO18/19,GPIO22/23；   SCIC对应的是GPIO62/63。          在编程初始化时，需要先将对应的GPIO管脚配置为SCI模式，才能使得这些管脚具有SCI功能；              B. SCI通信中带有格式信息的数据字符叫帧，下面是典型的数据帧格式         C. 下面单独介绍一下SCI波特率设置寄存器SCIHBAUD和SCILBAUD，0-15是高字节与低字节连在一起，构成16位波特率设置寄存器BRR。
    BRR = SCIHBAUD + SCILBAUD     如果1<= BRR <=65535，那么SCI波特率=LSPCLK / ( (BRR+1) * 8 )，由此，可以带入你需要的波特率，既可以得到BRR的值；     如果BRR = 0，那么SCI波特率=LSPCLK/ 16
   D. SCI模块发送和接受数据的原理：

3.SCI串口编程

   A.先初始化IO管脚 (以SCI-A为例，SCI-B、SCI-C的初始化方法一样，就是照着改对应的管脚就行) void InitSciaGpio() //初始化SCIA的GPIO管脚为例子 { EALLOW; //根据硬件设计决定采用GPIO28/29和GPIO35/36中的哪一组。这里以35/36为例 //定义管脚为上拉 GpioCtrlRegs.GPBPUD.bit.GPIO36 = 0; GpioCtrlRegs.GPBPUD.bit.GPIO35 = 0; //定义管脚为异步输入 GpioCtrlRegs.GPBQSEL1.bit.GPIO36 = 3; //配置管脚为SCI功能管脚 GpioCtrlRegs.GPBMUX1.bit.GPIO36 = 1; GpioCtrlRegs.GPBMUX1.bit.GPIO35 = 1; EDIS; }    B.SCI初始化配置 void scia_init() { SciaRegs.SCICCR.all =0x0007; // 1 stop bit, No loopback // No parity,8 char bits, // async mode, idle-line protocol SciaRegs.SCICTL1.all =0x0003; // enable TX, RX, internal SCICLK, // Disable RX ERR, SLEEP, TXWAKE SciaRegs.SCICTL2.bit.TXINTENA =1; //发送中断使能 SciaRegs.SCICTL2.bit.RXBKINTENA =1;//接收中断使能 SciaRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 37.5MHz. SciaRegs.SCILBAUD =0x00E7; SciaRegs.SCICTL1.all =0x0023; // Relinquish SCI from Reset }    C.接着进行中断的配置 EALLOW; // This is needed to write to EALLOW protected registers PieVectTable.SCIRXINTA = &sciaRxIsr; PieVectTable.SCITXINTA = &sciaTxIsr; PieVectTable.SCIRXINTB = &scibRxIsr; PieVectTable.SCITXINTB = &scibTxIsr; EDIS; // This is needed to disable write to EALLOW protected registers     D.上面是将SCIA和SCIB的中断服务程序连到PIE的中断表中，发生中断就会跑到你的ISR去了，下面是开中断： PieCtrlRegs.PIECTRL.bit.ENPIE = 1; // Enable the PIE block PieCtrlRegs.PIEIER9.bit.INTx1=1; // PIE Group 9, int1 PieCtrlRegs.PIEIER9.bit.INTx2=1; // PIE Group 9, INT2 PieCtrlRegs.PIEIER9.bit.INTx3=1; // PIE Group 9, INT3 PieCtrlRegs.PIEIER9.bit.INTx4=1; // PIE Group 9, INT4 IER = 0x100; // Enable CPU INT EINT;     这样串口基本就OK了。
上面的配置是配置典型的串口中断程序； 下面是一个SCI例程： /* * Serial.c * * Created on: 2014-12-8 * Author: SCOTT */ #include "DSP2833x_Device.h" // DSP2833x Headerfile Include File #include "DSP2833x_Examples.h" // CPU_FRQ_100MHZ is in it! void scib_fifo_init() { ScibRegs.SCIFFTX.all = 0xe040; ScibRegs.SCIFFRX.all = 0x204f; ScibRegs.SCIFFCT.all = 0x0; } /* void scib_echoback_init() { ScibRegs.SCICCR.all = 0x0007; // one stop bit,8 data bit,No parity, No Lookback ScibRegs.SCICTL1.all = 0x0003; // enable TX, RX, internal SCICLK, // Disable RX ERR, SLEEP, TXWAKE ScibRegs.SCICTL2.all =0x0003; ScibRegs.SCICTL2.bit.TXINTENA = 1; // TX interrupt enable ScibRegs.SCICTL2.bit.RXBKINTENA =1; #if (CPU_FRQ_150MHZ) ScibRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 37.5MHz. 150/4 = 37.5MHZ ScibRegs.SCILBAUD =0x00E7; #endif #if (CPU_FRQ_100MHZ) ScibRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 20MHz. ScibRegs.SCILBAUD =0x0044; #endif ScibRegs.SCICTL1.all =0x0023; // Relinquish SCI from Reset } */ void scib_echoback_init() { ScibRegs.SCICCR.all = 0x0007; // one stop bit,8 data bit,No parity, No Lookback ScibRegs.SCICTL1.all = 0x0003; // enable TX, RX, internal SCICLK, // Disable RX ERR, SLEEP, TXWAKE ScibRegs.SCICTL2.all =0x0003; // RX TX Interrupt enable ScibRegs.SCICTL2.bit.TXINTENA = 1; // TX interrupt enable ScibRegs.SCICTL2.bit.RXBKINTENA =1; // RX interrupt enable #if (CPU_FRQ_150MHZ) ScibRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 37.5MHz. 150/4 = 37.5MHZ ScibRegs.SCILBAUD =0x00E7; #endif #if (CPU_FRQ_100MHZ) ScibRegs.SCIHBAUD =0x0001; // 9600 baud @LSPCLK = 20MHz. ScibRegs.SCILBAUD =0x0044; #endif ScibRegs.SCIFFTX.all = 0xC020; ScibRegs.SCIFFRX.all = 0x0021; // Receive FIFO generates interrupt when the FIFO status bits (RXFFST4–0) and FIFO level bits //(RXFFIL4–0) match (i.e., are greater than or equal to). Default value of these bits after reset //–11111. This will avoid frequent interrupts, after reset, as the receive FIFO will be empty mos // t of the time. ScibRegs.SCIFFCT.all = 0x00; ScibRegs.SCIFFTX.bit.TXFIFOXRESET=1; ScibRegs.SCIFFRX.bit.RXFIFORESET=1; ScibRegs.SCICTL1.all =0x0023; // Relinquish SCI from Reset } void scib_xmit(int c) { //while (ScicRegs.SCIFFTX.bit.TXFFST != 0) {} //==0 -> transmit BUF is empty,can receive new data while(ScibRegs.SCICTL2.bit.TXRDY != 1){} //also right,but the way of tool's display is different ScibRegs.SCITXBUF = c; } void scib_msg(char *msg) { int i; i = 0; while('

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