iic.c

umon bootloader source code, support mips cpu.

#include "iic.h"

void IICDelayLoop()
{
    asm volatile (
    "nop\n"
    "nop\n"
    "nop\n"
    "nop\n"
    "nop\n"
    "nop\n"
    "nop\n"
    "nop");
}

void IICDelay(int cnt)
{
    int i;
    for(i=0; i<10*cnt; i++)
        IICDelayLoop();
}

void IICinit()
{
	  IIC_SDA_OUT();
    IIC_SDA_SET();
    IIC_SCL_OUT();
    IIC_SCL_SET();
}

void IICStart(void)          /* statr the iic bus */
{
	
		IIC_SDA_OUT();
    IIC_SDA_SET();
    IIC_SCL_OUT();
    IIC_SCL_SET();
    IICDelay(IIC_PUSH_DELAY);
	
    IIC_SDA_OUT();    /*does this option necessary ?*/
    IIC_SDA_CLR();
    IICDelay(IIC_PUSH_DELAY);
    IIC_SCL_CLR();
    IICDelay(IIC_PUSH_DELAY);
}
void IICStop(void)           /* stop the iic bus */
{
    IIC_SDA_OUT();
    IIC_SDA_CLR();
    IICDelay(IIC_PUSH_DELAY);
    IIC_SCL_SET();
    IICDelay(IIC_PUSH_DELAY);
    IIC_SDA_SET();
    IICDelay(IIC_PUSH_DELAY);
}


void IICWrite(int buf)       /* write the iic bus */
{
    int i;
    IIC_SDA_OUT();
    buf &= 0xff;
    for(i = 0; i <= 7; i++)
    {
        if((buf & 0x80))
            IIC_SDA_SET();
        else
            IIC_SDA_CLR();
        IICDelay(IIC_PUSH_DELAY);
        IIC_SCL_SET();
        IICDelay(IIC_PUSH_DELAY);
        IIC_SCL_CLR();
        IICDelay(IIC_PUSH_DELAY);
        buf = buf << 1;
    }
}
int IICChkAck(void)         /* chack the acknowledge signel */
{
    int WaitTime;
    IIC_SDA_IN();
    IICDelay(IIC_PUSH_DELAY);
    IIC_SCL_SET();
    IICDelay(IIC_PUSH_DELAY);
    WaitTime = IIC_WAIT_TIME;
    while(IIC_SDA_GET())
    {
        WaitTime--;
        if(WaitTime <= 0)
            break;
    }
    /* to do : read ack signal */
    IIC_SCL_CLR();
    IICDelay(IIC_PUSH_DELAY);
    /* to do : add err deal */
    if(WaitTime != 0)
        return IIC_ACK_SUCCESS;
    printf("iic time out!\n");
    return IIC_ACK_ERROR;
}



int IICWriteByte(int SlaveAddr, int ByteAddr, int data, int mode)
{
    int addr;
    addr = (SlaveAddr & 0x7f) << 1;
    //printf("%d  ", addr);
    IICStart();
    IICWrite(addr);
    if(IICChkAck() != IIC_ACK_SUCCESS)
    {
        IICStop();
        return IIC_ERROR;
    }
    IICWrite(ByteAddr);
    //printf("%d  ", ByteAddr);
    if(IICChkAck() != IIC_ACK_SUCCESS)
    {
        IICStop();
        return IIC_ERROR;
    }
    IICWrite(data);
    //printf("%d\n", data);
    if(IICChkAck() != IIC_ACK_SUCCESS)
    {
        IICStop();
        return IIC_ERROR;
    }
    IICStop();
    return IIC_OK;
}

void ak8817_reset(void)
{
	

	AK8817_RESET_OUT();
	AK8817_RESET_SET();
	
	IICDelay(10);

	  
	
	AK8817_RESET_OUT();
	AK8817_RESET_CLR();
	
	IICDelay(10);

	
	
	AK8817_RESET_OUT();
	AK8817_RESET_SET();
	
	IICDelay(10);
	

}