[thainguyenduong]

mình đang đọc dữ liệu từ con cảm biến MLX90614 bằng PIC18F4620 bằng SMBUS, tuy nhiên bị lỗi khi đọc về toàn là 0xFFFF, ai có biết và kinh nghiệm về phần này có thể cho mình vài tham khảo được không.
đây là code của mình

void I2C1_init(void) // init I2C1 as master
{
TRISCbits.TRISC3 = 1; // LT4100 SCK, Smart battery SCK
TRISCbits.TRISC4 = 1; // LT4100 SDA, Smart battery SDA
//PIE1bits.SSPIE = 1;
SSPCON1 = 0x28; //enable serial port and configure SDA and SCL
SSPSTATbits.SMP = 0; //slew rate disable and configered to input level to I2C (< 100k)
SSPSTATbits.CKE = 1; // Enable input logic thresholds to SMBus compatable
SSPADD = 49; // baud rate fixed to
SSPCON2 = 0x00;
//SSPCON2bits.ACKEN = 1;
}

void I2C1_Idle(void)
{
//while (SSP1STATbits.BF); // Wait for bus Idle (BF - is high while transmission in progress)
while ((SSPCON2 & 0x1F) | (SSPSTATbits.R_W));
}
void I2C1SSPIFWait(void)
{
while (PIR1bits.SSPIF != 1);
PIR1bits.SSPIF = 0;
}
void I2C1_start(void)
{
I2C1_Idle(); // Wait for Bus Idle

SSPCON2bits.SEN = 1;
I2C1SSPIFWait();
}
void I2C1_repeated_start(void)
{
SSPCON2bits.RSEN = 1;
I2C1SSPIFWait();
}
void I2C1_stop(void)
{
SSPCON2bits.PEN = 1; // STOP condition
I2C1SSPIFWait();
}

void I2C1Ack(void)
{
SSPCON2bits.ACKDT = 0; /* Acknowledge data bit, 0 = ACK */
SSPCON2bits.ACKEN = 1; /* Ack data enabled */
while(SSPCON2bits.ACKEN); /* wait for ack data to send on bus */
}

void I2C1Nak(void)
{
SSPCON2bits.ACKDT = 1; /* Acknowledge data bit, 1 = NAK */
SSPCON2bits.ACKEN = 1; /* Ack data enabled */
while(SSPCON2bits.ACKEN); /* wait for ack data to send on bus */
}
void I2C1RecieveEnable(void)
{
SSPCON2bits.RCEN = 1; //enable receive enable bit
I2C1SSPIFWait();
}
//address msb bits. LSB read/write 1/0 bit
void I2C1_byte_write(unsigned char dev_add, unsigned char loc_add, unsigned char loc_dat)
{
I2C1_start(); // SMBus START
SSPBUF = dev_add; // temp_add;//device add + write
I2C1SSPIFWait();
SSPBUF = loc_add; // Storage Address (command)
I2C1SSPIFWait();
SSPBUF = loc_dat; // data
I2C1SSPIFWait();
I2C1_stop(); // SMBus STOP
}

void I2C1_word_write(unsigned char dev_add, unsigned char loc_add, unsigned int loc_dat)
{
unsigned char loc_dat_msb = 0, loc_dat_lsb = 0;
loc_dat_msb = ((loc_dat & 0xFF00) >> 8);
loc_dat_lsb = (loc_dat & 0x00FF);
I2C1_start(); // SMBus START
SSPBUF = dev_add; // device add + write bit
I2C1SSPIFWait();
SSPBUF = loc_add; // Storage Address (command)
I2C1SSPIFWait();
SSPBUF = loc_dat_lsb; // LSB data
I2C1SSPIFWait();
SSPBUF = loc_dat_msb; // MSB data
I2C1SSPIFWait();
I2C1_stop(); // SMBus STOP
}

unsigned char I2C1_byte_read(unsigned char dev_add, unsigned char loc_add)
{
unsigned char read_dat = 0;
unsigned char temp_add = (dev_add | 0x01);
I2C1_start(); // SMBus START
SSPBUF = dev_add; // Slave Address with Write Bit
I2C1SSPIFWait();
//pointing to specific location
SSPBUF = loc_add; //Command Code / add location
I2C1SSPIFWait();
//I2C1_repeated_start();
SSPBUF = temp_add; //Slave Address + Read Bit
I2C1SSPIFWait();

read_dat = SSPBUF; //saving data into some register
// SSPCON2bits.ACKDT = 0; // Send an ack bit
// SSPCON2bits.ACKEN = 1;
// while (SSPCON2bits.ACKEN); // Wait for ack to finish
I2C1_stop(); // SMBus STOP
return (read_dat);
}
unsigned int I2C1_Word_read(unsigned char dev_add, unsigned char loc_add)
{
unsigned int read_dat_msb = 0, read_dat_lsb = 0, read_dat = 0, read_dat_pec = 0;
unsigned char temp_add = (dev_add | 0x01); //((dev_add << 1) | 0x01); //Fz_Mod

I2C1_start(); // SMBus START
SSPBUF = dev_add; // Slave Address with Write Bit
I2C1SSPIFWait();

//pointing to specific location
SSPBUF = loc_add; //Command Code / add location
I2C1SSPIFWait();

I2C1_repeated_start(); // Repeated Start
SSPBUF = temp_add; //Slave Address + Read Bit
I2C1SSPIFWait();
I2C1RecieveEnable(); // Receive Enable


read_dat_lsb = SSPBUF; //saving data into some register


I2C1Ack(); // ACK
I2C1RecieveEnable(); // Receive Enable


read_dat_msb = SSPBUF; //saving data into some register


I2C1Nak(); // ACK
I2C1RecieveEnable(); // Receive Enable

read_dat_pec = SSPBUF;

//I2C1Ack(); // NACK
I2C1_stop(); // SMBus STOP

read_dat_msb = read_dat_msb << 8;
read_dat = read_dat_msb | read_dat_lsb;

return (read_dat);


}