IIS是飛利浦公司定義的一種用于音頻傳輸?shù)臄?shù)字總線,LPC1768支持該總線, I2S接口為一條3線串行總線，含有1根數(shù)據(jù)線、1根時(shí)鐘線和1根字選擇信號(hào)線?；镜腎2S連接具有一個(gè)主機(jī)（其總是為主機(jī)）和一個(gè)從機(jī)。LPC1700系列Cortex—M3微控制器的I2S提供了彼此獨(dú)立的發(fā)送和接收通道，每個(gè)通道都可作為主機(jī)或從機(jī).

使用代碼如下

void IISInit(void)

{

//打開IIS時(shí)鐘

LPC_SC->PCONP|=1<<27;

LPC_SC->PCLKSEL1&=~(0X03<<22); //時(shí)鐘選擇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輸出

LPC_I2S->I2SRXMODE|=1<<3;//禁止RCLK輸出

//16位數(shù)據(jù) 立體聲 使能fifo 主模式 采樣周期32 僅僅發(fā)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 不使能接受中斷,發(fā)送中斷

NVIC_EnableIRQ(I2S_IRQn);

FillBuffer(Buf_L,1000,Buf_R,1000);

}

void IISStart()

{

LPC_I2S->I2SDAO&=(~(1<<4));//復(fù)位停止訪問fifo使能并開始發(fā)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;

}

}

}