#include "mlx90614.h"


#define ACK	 0 
#define	NACK 1 
#define SA				0x00 
#define RAM_ACCESS		0x00 
#define EEPROM_ACCESS	0x20 
#define RAM_TOBJ1		0x07 

#define SMBUS_PORT	GPIOB      
#define SMBUS_SCK		GPIO_Pin_10 
#define SMBUS_SDA		GPIO_Pin_11 

#define RCC_APB2Periph_SMBUS_PORT		RCC_APB2Periph_GPIOB

#define SMBUS_SCK_H()	    SMBUS_PORT->BSRR = SMBUS_SCK 
#define SMBUS_SCK_L()	    SMBUS_PORT->BRR = SMBUS_SCK 
#define SMBUS_SDA_H()	    SMBUS_PORT->BSRR = SMBUS_SDA
#define SMBUS_SDA_L()	    SMBUS_PORT->BRR = SMBUS_SDA

#define SMBUS_SDA_PIN()	    SMBUS_PORT->IDR & SMBUS_SDA //??????


void SMBus_StartBit(void)
{
    SMBUS_SDA_H();		// Set SDA line
    SMBus_Delay(5);	    // Wait a few microseconds
    SMBUS_SCK_H();		// Set SCL line
    SMBus_Delay(5);	    // Generate bus free time between Stop
    SMBUS_SDA_L();		// Clear SDA line
    SMBus_Delay(5);	    // Hold time after (Repeated) Start

	
    SMBUS_SCK_L();	    // Clear SCL line
    SMBus_Delay(5);	    // Wait a few microseconds
}

/*******************************************************************************
* Function Name  : SMBus_StopBit
* Description    : Generate STOP condition on SMBus
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
void SMBus_StopBit(void)
{
    SMBUS_SCK_L();		// Clear SCL line
    SMBus_Delay(5);	    // Wait a few microseconds
    SMBUS_SDA_L();		// Clear SDA line
    SMBus_Delay(5);	    // Wait a few microseconds
    SMBUS_SCK_H();		// Set SCL line
    SMBus_Delay(5);	    // Stop condition setup time(Tsu:sto=4.0us min)
    SMBUS_SDA_H();		// Set SDA line?SCK=1?,???SDA?0?1??????(???)
}


u8 SMBus_SendByte(u8 Tx_buffer)
{
    u8	Bit_counter;
    u8	Ack_bit;
    u8	bit_out;

    for(Bit_counter=8; Bit_counter; Bit_counter--)
    {
        if (Tx_buffer&0x80)
        {
            bit_out=1;   // If the current bit of Tx_buffer is 1 set bit_out
        }
        else
        {
            bit_out=0;  // else clear bit_out
        }
        SMBus_SendBit(bit_out);		// Send the current bit on SDA
        Tx_buffer<<=1;				// Get next bit for checking
    }

    Ack_bit=SMBus_ReceiveBit();		// Get acknowledgment bit
    return	Ack_bit;
}


void SMBus_SendBit(u8 bit_out)
{
    if(bit_out==0)
    {
        SMBUS_SDA_L();
    }
    else
    {
        SMBUS_SDA_H();
    }
    SMBus_Delay(2);					// Tsu:dat = 250ns minimum
    SMBUS_SCK_H();					// Set SCL line
    SMBus_Delay(6);					// High Level of Clock Pulse
    SMBUS_SCK_L();					// Clear SCL line
    SMBus_Delay(3);					// Low Level of Clock Pulse
//	SMBUS_SDA_H();				    // Master release SDA line ,
    return;
}


u8 SMBus_ReceiveBit(void)
{
    u8 Ack_bit;

    SMBUS_SDA_H();          //?????????,????
	SMBus_Delay(2);			// High Level of Clock Pulse
    SMBUS_SCK_H();			// Set SCL line
    SMBus_Delay(5);			// High Level of Clock Pulse
    if (SMBUS_SDA_PIN())
    {
        Ack_bit=1;
    }
    else
    {
        Ack_bit=0;
    }
    SMBUS_SCK_L();			// Clear SCL line
    SMBus_Delay(3);			// Low Level of Clock Pulse

    return	Ack_bit;
}


u8 SMBus_ReceiveByte(u8 ack_nack)
{
    u8 	RX_buffer;
    u8	Bit_Counter;

    for(Bit_Counter=8; Bit_Counter; Bit_Counter--)
    {
        if(SMBus_ReceiveBit())			// Get a bit from the SDA line
        {
            RX_buffer <<= 1;			// If the bit is HIGH save 1  in RX_buffer
            RX_buffer |=0x01;
        }
        else
        {
            RX_buffer <<= 1;			// If the bit is LOW save 0 in RX_buffer
            RX_buffer &=0xfe;
        }
    }
    SMBus_SendBit(ack_nack);			// Sends acknowledgment bit
    return RX_buffer;
}


void SMBus_Delay(u16 time)
{
    u16 i, j;
    for (i=0; i<4; i++)
    {
        for (j=0; j<time; j++);
    }
}


void SMBus_Init()
{
    GPIO_InitTypeDef    GPIO_InitStructure;

	RCC_APB2PeriphClockCmd(RCC_APB2Periph_SMBUS_PORT, ENABLE);

    GPIO_InitStructure.GPIO_Pin = SMBUS_SCK | SMBUS_SDA;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_OD;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(SMBUS_PORT, &GPIO_InitStructure);

    SMBUS_SCK_H();
    SMBUS_SDA_H();
}

u16 SMBus_ReadMemory(u8 slaveAddress, u8 command)
{
    u16 data;			
    u8 Pec;				
    u8 DataL=0;			
    u8 DataH=0;
    u8 arr[6];
    u8 PecReg;
    u8 ErrorCounter;

    ErrorCounter=0x00;
	slaveAddress <<= 1;
	
    do
    {
repeat:
        SMBus_StopBit();
        --ErrorCounter;				    //Pre-decrement ErrorCounter
        if(!ErrorCounter) 			    //ErrorCounter=0?
        {
            break;					    //Yes,go out from do-while{}
        }

        SMBus_StartBit();				//Start condition
        if(SMBus_SendByte(slaveAddress))//Send SlaveAddress ???Wr=0????????
        {
            goto	repeat;			    //Repeat comunication again
        }
        if(SMBus_SendByte(command))	    //Send command
        {
            goto	repeat;		    	//Repeat comunication again
        }

        SMBus_StartBit();					//Repeated Start condition
        if(SMBus_SendByte(slaveAddress+1))	//Send SlaveAddress ???Rd=1????????
        {
            goto	repeat;             	//Repeat comunication again
        }

        DataL = SMBus_ReceiveByte(ACK);	//Read low data,master must send ACK
        DataH = SMBus_ReceiveByte(ACK); //Read high data,master must send ACK
        Pec = SMBus_ReceiveByte(NACK);	//Read PEC byte, master must send NACK
        SMBus_StopBit();				//Stop condition

        arr[5] = slaveAddress;		//
        arr[4] = command;			//
        arr[3] = slaveAddress+1;	//Load array arr
        arr[2] = DataL;				//
        arr[1] = DataH;				//
        arr[0] = 0;					//
        PecReg=PEC_Calculation(arr);//Calculate CRC
    }
    while(PecReg != Pec);		//If received and calculated CRC are equal go out from do-while{}

	data = (DataH<<8) | DataL;	//data=DataH:DataL
    return data;
}


u8 PEC_Calculation(u8 pec[])
{
    u8 	crc[6];
    u8	BitPosition=47;
    u8	shift;
    u8	i;
    u8	j;
    u8	temp;

    do
    {
        /*Load pattern value 0x000000000107*/
        crc[5]=0;
        crc[4]=0;
        crc[3]=0;
        crc[2]=0;
        crc[1]=0x01;
        crc[0]=0x07;

        /*Set maximum bit position at 47 ( six bytes byte5...byte0,MSbit=47)*/
        BitPosition=47;

        /*Set shift position at 0*/
        shift=0;

        /*Find first "1" in the transmited message beginning from the MSByte byte5*/
        i=5;
        j=0;
        while((pec[i]&(0x80>>j))==0 && i>0)
        {
            BitPosition--;
            if(j<7)
            {
                j++;
            }
            else
            {
                j=0x00;
                i--;
            }
        }/*End of while */

        /*Get shift value for pattern value*/
        shift=BitPosition-8;

        /*Shift pattern value */
        while(shift)
        {
            for(i=5; i<0xFF; i--)
            {
                if((crc[i-1]&0x80) && (i>0))
                {
                    temp=1;
                }
                else
                {
                    temp=0;
                }
                crc[i]<<=1;
                crc[i]+=temp;
            }/*End of for*/
            shift--;
        }/*End of while*/

        /*Exclusive OR between pec and crc*/
        for(i=0; i<=5; i++)
        {
            pec[i] ^=crc[i];
        }/*End of for*/
    }
    while(BitPosition>8); /*End of do-while*/

    return pec[0];
}


float SMBus_ReadTemp(void)
{   
	float temp;
	temp = SMBus_ReadMemory(SA, RAM_ACCESS|RAM_TOBJ1)*0.02-273.15;
	return temp;
}