MAX6900_REG_CENTURY
i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];
bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
.len = sizeof(buf[MAX6900_REG_CENTURY]),
.buf = &buf[MAX6900_REG_CENTURY]