/Designs/MRAKOMER2/SW/Ondrejov/teplomer/smb.c
0,0 → 1,261
/************ SMB driver ************/
 
#define SA 0x00 // Slave Address (0 for single slave / 0x5A<<1 default)
#define RAM_Access 0x00 // RAM access command
#define RAM_Tobj1 0x07 // To1 address in the RAM
#define RAM_Tamb 0x06 // Ta address in the RAM
 
 
// High and Low level of clock
#define HIGHLEV 40 // max. 50us
#define LOWLEV 100 // max. 30ms
#define TBUF 20
 
// SMBus control signals
#define SCL PIN_B0
#define SDA PIN_B1
 
#define mSDA_HIGH() output_float(SDA); // SDA float
#define mSDA_LOW() output_low(SDA); // SDA low
#define mSCL_HIGH() output_float(SCL); // SCL float
#define mSCL_LOW() output_low(SCL); // SCL low
 
#define ACK 0
#define NACK 1
 
//**********************************************************************************************
// START CONDITION ON SMBus
//**********************************************************************************************
//Name: START_bit
//Function: Generate START condition on SMBus
//Parameters: No
//Return: No
//Comments: Refer to "System Managment BUS(SMBus) specification Version 2.0"
// or AN"SMBus communication with MLX90614" on the website www.melexis.com
//**********************************************************************************************
void SMB_START_bit(void)
{
// disable_interrupts(GLOBAL);
mSDA_HIGH(); // Set SDA line
delay_us( TBUF ); // Wait a few microseconds
mSCL_HIGH(); // Set SCL line
delay_us( TBUF ); // Generate bus free time between Stop
// and Start condition (Tbuf=4.7us min)
mSDA_LOW(); // Clear SDA line
delay_us( TBUF ); // Hold time after (Repeated) Start Condition.
// After this period, the first clock is generated.
// (Thd:sta=4.0us min)
mSCL_LOW(); // Clear SCL line
// enable_interrupts(GLOBAL);
delay_us( TBUF ); // Wait a few microseconds
}
 
//*********************************************************************************************
// STOP CONDITION ON SMBus
//*********************************************************************************************
//Name: STOPbit
//Function: Generate STOP condition on SMBus
//Parameters: No
//Return: No
//Comments: Refer to "System Managment BUS(SMBus) specification Version 2.0"
// or AN"SMBus communication with MLX90614" on the website www.melexis.com
//*********************************************************************************************
void SMB_STOP_bit(void)
{
// disable_interrupts(GLOBAL);
mSDA_HIGH();
mSCL_LOW(); // Clear SCL line
delay_us( TBUF ); // Wait a few microseconds
mSDA_LOW(); // Clear SDA line
delay_us( TBUF ); // Wait a few microseconds
mSCL_HIGH(); // Set SCL line
delay_us( TBUF ); // Stop condition setup time(Tsu:sto=4.0us min)
mSDA_HIGH(); // Set SDA line
// enable_interrupts(GLOBAL);
}
 
 
void SMB_send_bit(unsigned char bit_out)
{
// disable_interrupts(GLOBAL);
if(bit_out==0) {mSDA_LOW();}
else {mSDA_HIGH();}
delay_us(3);
mSCL_HIGH(); // Set SCL line
delay_us( HIGHLEV ); // High Level of Clock Pulse
mSCL_LOW(); // Clear SCL line
 
//!!! toggle_dome();
delay_us(1);
 
delay_us( LOWLEV ); // Low Level of Clock Pulse
// mSDA_HIGH(); // Master release SDA line ,
// enable_interrupts(GLOBAL);
 
//!!! toggle_dome();
delay_us(1);
return;
}
 
unsigned char SMB_Receive_bit(void)
{
unsigned char Ack_bit;
 
// disable_interrupts(GLOBAL);
mSDA_HIGH(); //_SDA_IO=1; // SDA-input
mSCL_HIGH(); // Set SCL line
delay_us( HIGHLEV ); // High Level of Clock Pulse
if(input(SDA)) Ack_bit=1; // \ Read acknowledgment bit, save it in Ack_bit
else Ack_bit=0; // /
mSCL_LOW(); // Clear SCL line
 
//!!! toggle_dome();
delay_us(1);
 
delay_us( LOWLEV ); // Low Level of Clock Pulse
// enable_interrupts(GLOBAL);
 
//!!! toggle_dome();
delay_us(1);
 
return Ack_bit;
}
 
 
//*********************************************************************************************
// TRANSMIT DATA ON SMBus
//*********************************************************************************************
//Name: TX_byte
//Function: Send a byte on SMBus
//Parameters: TX_buffer ( the byte which will be send on the SMBus )
//Return: Ack_bit ( acknowledgment bit )
//Comments: Sends MSbit first
//*********************************************************************************************
unsigned char SMB_TX_byte(unsigned char Tx_buffer)
{
unsigned char Bit_counter;
unsigned char Ack_bit;
unsigned char 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
 
SMB_send_bit(bit_out); // Send the current bit on SDA
Tx_buffer<<=1; // Get next bit for checking
}
 
Ack_bit=SMB_Receive_bit(); // Get acknowledgment bit
 
return Ack_bit;
}
 
//*********************************************************************************************
// RECEIVE DATA ON SMBus
//*********************************************************************************************
//Name: RX_byte
//Function: Receive a byte on SMBus
//Parameters: ack_nack (ackowlegment bit)
//Return: RX_buffer(Received byte)
//Comments: MSbit is received first
//*********************************************************************************************
unsigned char SMB_RX_byte(unsigned char ack_nack)
{
unsigned char RX_buffer;
unsigned char Bit_Counter;
 
for(Bit_Counter=8; Bit_Counter; Bit_Counter--)
{
if(SMB_Receive_bit()) // Get a bit from the SDA line
{
RX_buffer <<= 1; // If the bit is HIGH save 1 in RX_buffer
RX_buffer |=0b00000001;
}
else
{
RX_buffer <<= 1; // If the bit is LOW save 0 in RX_buffer
RX_buffer &=0b11111110;
}
}
 
SMB_send_bit(ack_nack); // Sends acknowledgment bit
 
return RX_buffer;
}
 
 
unsigned char PEC_calculation(unsigned char pec[]) // CRC calculation
{
unsigned char crc[6];
unsigned char BitPosition=47;
unsigned char shift;
unsigned char i;
unsigned char j;
unsigned char temp;
 
do
{
crc[5]=0; /* Load CRC value 0x000000000107 */
crc[4]=0;
crc[3]=0;
crc[2]=0;
crc[1]=0x01;
crc[0]=0x07;
BitPosition=47; /* Set maximum bit position at 47 */
shift=0;
 
//Find first 1 in the transmited message
i=5; /* Set highest index */
j=0;
while((pec[i]&(0x80>>j))==0 && i>0)
{
BitPosition--;
if(j<7)
{
j++;
}
else
{
j=0x00;
i--;
}
//!!! toggle_dome();
delay_us(1);
 
}
 
shift=BitPosition-8; /*Get shift value for crc value*/
 
 
//Shift crc 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;
}
shift--;
//!!! toggle_dome();
delay_us(1);
 
}
 
//Exclusive OR between pec and crc
for(i=0; i<=5; i++)
{
pec[i] ^=crc[i];
}
} while(BitPosition>8);
 
return pec[0];
}