giao tiếp i2c với ds1307, giúp mình giải thích đoạn code này với!
 

phần data=sec1+(sec2<<4);
data=data&0b01111111;
i2c_write(data);
có nghĩa là sao?

sec2<<4; // sec2 dịch trái 4 bit
ví dụ: sec2=0b00001111 , sec2<<4 => sec2=0b11110000

data&0b01111111;//nhân từng bit giữa data và 0b01111111
ví dụ: a=data&0b00000111, data=0b01011010

0b01011010
x
0b00000111
a = 0b00000010

mình tham khảo code như thế này, viết bằng ccs , báo lỗi, mấy bạn giúp mình với, đang làm đồ án cái lịch vạn niên

Bạn cần nêu vắn tắt về nội dung chương trình, đặc biệt là nói rõ về thông báo lỗi. Như vậy mọi người mới giúp được.

Tặng các bạn file thư viện ds1307

////////////////////////////////////////////////////////////////////////////////
/// DS1307.C ///
/// Driver for Real Time Clock ///
/// ///
/// ds1307_init() - Enable oscillator without clearing the seconds register -///
/// used when PIC loses power and DS1307 run from 3V BAT ///
/// - Disable squarewave output ///
/// ///
/// ds1307_set_date_time(day,mth,year,dow,hour,min,sec ) Set the date/time ///
/// ///
/// ds1307_get_date(day,mth,year,dow) Get the date ///
/// ///
/// ds1307_get_time(hr,min,sec) Get the time ///
/// ///
////////////////////////////////////////////////////////////////////////////////

#define RTC_SDA PIN_D5
#define RTC_SCL PIN_D4

#use i2c(master, sda=RTC_SDA, scl=RTC_SCL)

BYTE bin2bcd(BYTE binary_value);
BYTE bcd2bin(BYTE bcd_value);

void ds1307_init(void)
{
BYTE seconds = 0;

i2c_start();
i2c_write(0xD0); // WR to RTC
i2c_write(0x00); // REG 0
i2c_start();
i2c_write(0xD1); // RD from RTC
seconds = bcd2bin(i2c_read(0)); // Read current "seconds" in DS1307
i2c_stop();
seconds &= 0x7F;

delay_us(3);

i2c_start();
i2c_write(0xD0); // WR to RTC
i2c_write(0x00); // REG 0
i2c_write(bin2bcd(seconds)); // Start oscillator with current "seconds value
i2c_start();
i2c_write(0xD0); // WR to RTC
i2c_write(0x07); // Control Register
i2c_write(0x80); // Disable squarewave output pin
i2c_stop();

}

void ds1307_set_date_time(BYTE day, BYTE mth, BYTE year, BYTE dow, BYTE hr, BYTE min, BYTE sec)
{
sec &= 0x7F;
hr &= 0x3F;

i2c_start();
i2c_write(0xD0); // I2C write address
i2c_write(0x00); // Start at REG 0 - Seconds
i2c_write(bin2bcd(sec)); // REG 0
i2c_write(bin2bcd(min)); // REG 1
i2c_write(bin2bcd(hr)); // REG 2
i2c_write(bin2bcd(dow)); // REG 3
i2c_write(bin2bcd(day)); // REG 4
i2c_write(bin2bcd(mth)); // REG 5
i2c_write(bin2bcd(year)); // REG 6
i2c_write(0x80); // REG 7 - Disable squarewave output pin
i2c_stop();
}

void ds1307_get_date(BYTE &day, BYTE &mth, BYTE &year, BYTE &dow)
{
i2c_start();
i2c_write(0xD0);
i2c_write(0x03); // Start at REG 3 - Day of week
i2c_start();
i2c_write(0xD1);
dow = bcd2bin(i2c_read() & 0x7f); // REG 3
day = bcd2bin(i2c_read() & 0x3f); // REG 4
mth = bcd2bin(i2c_read() & 0x1f); // REG 5
year = bcd2bin(i2c_read(0)); // REG 6
i2c_stop();
}

void ds1307_get_time(BYTE &hr, BYTE &min, BYTE &sec)
{
i2c_start();
i2c_write(0xD0);
i2c_write(0x00); // Start at REG 0 - Seconds
i2c_start();
i2c_write(0xD1);
sec = bcd2bin(i2c_read() & 0x7f);
min = bcd2bin(i2c_read() & 0x7f);
hr = bcd2bin(i2c_read(0) & 0x3f);
i2c_stop();

}

BYTE bin2bcd(BYTE binary_value)
{
BYTE temp;
BYTE retval;

temp = binary_value;
retval = 0;

while(1)
{
// Get the tens digit by doing multiple subtraction
// of 10 from the binary value.
if(temp >= 10)
{
temp -= 10;
retval += 0x10;
}
else // Get the ones digit by adding the remainder.
{
retval += temp;
break;
}
}

return(retval);
}


// Input range - 00 to 99.
BYTE bcd2bin(BYTE bcd_value)
{
BYTE temp;

temp = bcd_value;
// Shifting upper digit right by 1 is same as multiplying by 8.
temp >>= 1;
// Isolate the bits for the upper digit.
temp &= 0x78;

// Now return: (Tens * 8) + (Tens * 2) + Ones

return(temp + (temp >> 2) + (bcd_value & 0x0f));
}