Adafruit 3028 DS3231 RTC Problem

Troubleshooting
4

Finally got to the bottom of the issue. Below is the standard function to read the RTC registers and pack in a DateTime struct/object:

DateTime DS3231::getTime()
{
    Wire.beginTransmission(DS3231_ADDRESS);
    Wire.write((byte)0);	
    Wire.endTransmission();
    Wire.requestFrom(DS3231_ADDRESS, 7);
    uint8_t ss = bcd2bin(Wire.read() & 0x7F);
    uint8_t mm = bcd2bin(Wire.read());
    uint8_t hh = bcd2bin(Wire.read());
    uint8_t dow= Wire.read();
    uint8_t d =  bcd2bin(Wire.read());
    uint8_t m =  bcd2bin(Wire.read());
    uint16_t y = bcd2bin(Wire.read()) + 2000;
    return DateTime (y, m, d, dow, hh, mm, ss);
}

This does not work - we’ll come to why later.

I had added a function to read the temperature on the DS3231 which worked fine.

float DS3231::getTemp()
{
	uint8_t _msb = read_i2c_register(DS3231_ADDRESS, DS3231_REG_TEMPM);
	uint8_t _lsb = read_i2c_register(DS3231_ADDRESS, DS3231_REG_TEMPL);
	return (float)_msb + ((_lsb >> 6) * 0.25f);
}

The obvious difference was the use of the read_i2c_register() function and the reading of one register at a time. I modified the getTime() function to use this function and read register by register - and now it works. Thus, setting the pointer to the first RTC register and requesting 7 bytes (as had been coded) does not work. I would be interested to understand why but for now I need to move on as I have wasted enough time on trying to solve this.

DateTime DS3231::getTime()
{
    uint8_t temp;
    temp = read_i2c_register(DS3231_ADDRESS, DS3231_REG_SEC);
    uint8_t ss = bcd2bin(temp & 0x7F);
    temp = read_i2c_register(DS3231_ADDRESS, DS3231_REG_MIN);
    uint8_t mm = bcd2bin(temp);
    temp = read_i2c_register(DS3231_ADDRESS, DS3231_REG_HOUR);
    uint8_t hh = bcd2bin(temp);
    temp = read_i2c_register(DS3231_ADDRESS, DS3231_REG_DOW);
    uint8_t dow = temp & 0x07;
    temp = read_i2c_register(DS3231_ADDRESS, DS3231_REG_DATE);
    uint8_t d =  bcd2bin(temp);
    temp = read_i2c_register(DS3231_ADDRESS, DS3231_REG_MON);
    uint8_t m =  bcd2bin(temp);
    temp = read_i2c_register(DS3231_ADDRESS, DS3231_REG_YEAR);
    uint16_t y = bcd2bin(temp) + 2000;
    return DateTime (y, m, d, dow, hh, mm, ss);
}
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