LPC1768的IIS通讯

IIS是飞利浦公司定义的一种用于音频传输的数字总线,LPC1768支持该总线, I2S接口为一条3线串行总线，含有1根数据线、1根时钟线和1根字选择信号线。基本的I2S连接具有一个主机（其总是为主机）和一个从机。LPC1700系列Cortex—M3微控制器的I2S提供了彼此独立的发送和接收通道，每个通道都可作为主机或从机.

使用代码如下

void IISInit(void)

{

    //打开IIS时钟

    LPC_SC->PCONP |= 1<<27;

    LPC_SC->PCLKSEL1 &= ~(0X03<<22);    //时钟选择25M

    //0.4 IIS RX CLK

    LPC_PINCON->PINSEL0 &= ~(0x03u<<8);

    LPC_PINCON->PINSEL0 |= (0x01u<<8);

    //0.5 IIS RX LR

    LPC_PINCON->PINSEL0 &= ~(0x03u<<10);

    LPC_PINCON->PINSEL0 |= (0x01u<<10);

    //0.6 IIS RX DAT

    LPC_PINCON->PINSEL0 &= ~(0x03u<<12);

    LPC_PINCON->PINSEL0 |= (0x01u<<12);

    //0.7 IIS TX CLK

    LPC_PINCON->PINSEL0 &= ~(0x03u<<14);

    LPC_PINCON->PINSEL0 |= (0x01u<<14);

    //0.8 IIS TX LR

    LPC_PINCON->PINSEL0 &= ~(0x03u<<16);

    LPC_PINCON->PINSEL0 |= (0x01u<<16);

    //0.9 IIS TX DAT

    LPC_PINCON->PINSEL0 &= ~(0x03u<<18);

    LPC_PINCON->PINSEL0 |= (0x01u<<18);

    //mclk  IIS TX MCLK

    LPC_PINCON->PINSEL9 &= ~(0x03u<<26);

    LPC_PINCON->PINSEL9 |= (0x01u<<26);

 

    //FS 48K DATALENGTH 16 MONO ON MCLK 256FS

    LPC_I2S->I2STXRATE = 0;

    LPC_I2S->I2STXRATE = (98<<8)| 100;       //X 98 Y 100 MCLK (25000000/2)*0.98 12250000

 

    LPC_I2S->I2SRXRATE = 0;

    LPC_I2S->I2SRXRATE =(98<<8)| 100;        //X 98 Y 100 MCLK (25000000/2)*0.98 12250000

 

    LPC_I2S->I2STXBITRATE = 7;           //BIT_RATE=MCLK/(7+1)=1531250  FS = 1531250/16/2 = 47.85

    LPC_I2S->I2SRXBITRATE = 7;           //BIT_RATE=MCLK/(7+1)=1531250  FS = 1531250/16/2 = 47.85

 

    LPC_I2S->I2STXMODE |= 1<<3; //禁止TCLK输出

    LPC_I2S->I2SRXMODE |= 1<<3; //禁止RCLK输出

 

    //16位数据 立体声 使能fifo 主模式 采样周期32 仅仅发送0

    LPC_I2S->I2SDAO = (1<<0)|(0<<2)|(0<<3)|(0<<4)|(0<<5)|(15<<6)|(0<<15);

    LPC_I2S->I2SDAI = ((16-1)<<6)|(0<<5)|(0<<4)|(0<<3)|(0<<2)|(1<<0);

 

    IIS_Stop();

    LPC_I2S->I2SIRQ = (0<<0)|(0<<1)|(32<<8)|(32<<16);  //32位fifo深度 不使能接受中断,发送中断

    NVIC_EnableIRQ(I2S_IRQn);

    FillBuffer(Buf_L,1000,Buf_R,1000);

}

void IISStart()

{

    LPC_I2S->I2SDAO &=  (~(1<<4)); //复位停止访问fifo使能并开始发送

    LPC_I2S->I2SDAO &=  (~(1<<3)); 

    LPC_I2S->I2SDAO &=  (~(1<<15));

}

 

void IISStartTransData(void)

{

    IISStart();

    LPC_I2S->I2SIRQ |= LPC_I2S->I2SIRQ | (1<<1);

}

 

void I2S_IRQHandler(void)

{

    u32 state=LPC_I2S->I2SSTATE;

    if(state&0x1)

    {

        if( ((state>>16)&0x1f)==0 )

        {  

            s16 datl=Buf_L[current_l++];

            s16 datr=Buf_R[current_r++];

            LPC_I2S->I2STXFIFO = (datr<<16) | (datl & 0xFFFF);

            if(current_l>=len_l)current_l=0;

            if(current_r>=len_r)current_r=0;

        }

    }

}