karita
08-12-2009, 06:20 PM
Đoạn code như sau, mấy pro cho hỏi 1 số vấn đề sau:
- Biến seconds trong đoạn code void ds1307_init(void) có tác dụng làm gì?
- Khi cần set lại thời gian cho con DS1307 thì mình phải thay đổi biến nào, vì mình nghe nói có thể thay đổi thời gian được khi đã set rồi.
- sec &= 0x7F;
hr &= 0x3F;
2 dòng này có tác dụng gì?
Xin cám ơn đã xem qua, mong nhận được reply sớm.^^!
^^! Đoạn code !^^
int8 dow,day,mth,year;
int8 hr,min,sec;
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(0x01); // 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));
}
- Biến seconds trong đoạn code void ds1307_init(void) có tác dụng làm gì?
- Khi cần set lại thời gian cho con DS1307 thì mình phải thay đổi biến nào, vì mình nghe nói có thể thay đổi thời gian được khi đã set rồi.
- sec &= 0x7F;
hr &= 0x3F;
2 dòng này có tác dụng gì?
Xin cám ơn đã xem qua, mong nhận được reply sớm.^^!
^^! Đoạn code !^^
int8 dow,day,mth,year;
int8 hr,min,sec;
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(0x01); // 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));
}