十 ARM9(2440)的IIC-理论知识及程序实例

_iicMode = POLLACK;//发送完后下面等待应答信号ACK

while(1)
{
rIICDS= slvAddr;
_iicStatus = 0x100;
rIICSTAT= 0xf0;//MasTx,Start启动
rIICCON= 0xaf;//Resumes IIC operation. 恢复IIC总线

while(_iicStatus==0x100);//未接收到ACk在此等待

if(!(_iicStatus&0x1))
break;//When ACK is receivedACK收到后跳出循环
}
rIICSTAT = 0xd0;//Stop MasTx condition 停止信号
rIICCON= 0xaf;//Resumes IIC operation.
Delay(1);//Wait until stop condtion is in effect.恢复
//Write is completed.
}

//**********************[ Rd24C080 ] ***********************************
void Rd24C080(U32 slvAddr,U32 addr,U8 *data)//首地址 内部地址 读取的数据存入的地址
{
_iicMode= SETRDADDR;//模式设为SETRDADDR
_iicPt= 0;
_iicData[0]= (U8)addr;//_iicData[0]存内部地址
_iicDataCount = 1;//计数值

rIICDS= slvAddr;//首地址0xa0
rIICSTAT = 0xf0;//MasTx,Start启动
//Clearing the pending bit isnt needed because the pending bit has been cleared.
while(_iicDataCount!=-1);//未读取完成

_iicMode= RDDATA;//完成后进入读取数据模式
_iicPt= 0;
_iicDataCount = 1;

rIICDS= slvAddr;
rIICSTAT= 0xb0;//MasRx,Start设置为主接收模式
rIICCON= 0xaf;//Resumes IIC operation.恢复IIC总线操作
while(_iicDataCount!=-1);//读取未完成

*data = _iicData[1];//1
}

//-------------------------------------------------------------------------
void __irq IicInt(void)
{
U32 iicSt,i;

rSRCPND = BIT_IIC;//Clear pending bit
rINTPND = BIT_IIC;
iicSt= rIICSTAT;//控制状态寄存器

if(iicSt & 0x8){}//When bus arbitration is failed.总线仲裁失败执行空操作
if(iicSt & 0x4){}//When a slave address is matched with IICADD从地址匹配执行空操作
if(iicSt & 0x2){}//When a slave address is 0000000b
if(iicSt & 0x1){}//When ACK isnt received未收到应答信号执行空操作

switch(_iicMode)
{
case POLLACK:
_iicStatus = iicSt;//控制状态寄存器的值赋给_iicStatus
break;

case RDDATA:
if((_iicDataCount--)==0)
{
_iicData[_iicPt++] = rIICDS;

rIICSTAT = 0x90;//Stop MasRx condition
rIICCON= 0xaf;//Resumes IIC operation.
Delay(1);//Wait until stop condtion is in effect.
//Too long time...
//The pending bit will not be set after issuing stop condition.
break;
}
_iicData[_iicPt++] = rIICDS;//The last data has to be read with no ack.

if((_iicDataCount)==0)
rIICCON = 0x2f;//Resumes IIC operation with NOACK.第一次不产生应答信号进行第二次读取并将第二次读取的
///////////////数据存入数组中（第一次和第二次读取的数据实际一样）
else
rIICCON = 0xaf;//Resumes IIC operation with ACK
break;

case WRDATA:
if((_iicDataCount--)==0)//首地址 ，内部地址和数据都发送完毕后
{
rIICSTAT = 0xd0;//Stop MasTx condition 产生停止信号
rIICCON= 0xaf;//Resumes IIC operation.恢复IIC总线
Delay(1);//Wait until stop condtion is in effect.
//The pending bit will not be set after issuing stop condition.
break;
}
rIICDS = _iicData[_iicPt++];//_iicData[0] has dummy.第一次中断后将内部地址addr的值存入IICDS第二次存入要写入的数据
for(i=0;i<10;i++);//for setup time until rising edge of IICSCL//延时

rIICCON = 0xaf;//resumes IIC operation.恢复IIC总线
break;

case SETRDADDR:
//Uart_Printf("[ S%d ]",_iicDataCount);
if((_iicDataCount--)==0)
break;//第二次中断跳出//IIC operation is stopped because of IICCON[4]
rIICDS = _iicData[_iicPt++];//第一次中断将内部地址addr存入移位寄存器
for(i=0;i<10;i++);//For setup time until rising edge of IICSCL
rIICCON = 0xaf;//Resumes IIC operation.
break;

default:
break;
}
}
void Delay(int x)
{
int k, j;
while(x)
{
for (k=0;k<=0xff;k++)
for(j=0;j<=0xff;j++);

x--;
}
}