DS3232RTC and SD libraries clashing

[nandakrpp]

Hello Jack,

First of all, thanks for DS3232RTC library. It works great on my system that wakes up Arduino Mega 2562 from sleep. I am using INT/SQW pin with the alarm interrupt code mentioned in https://github.com/JChristensen/DS3232RTC/issues/5 without a problem on its own. But the alarm is not triggered since the SD card library was implemented. I was wondering if you have encountered the same problem.

Regards.

[JChristensen]

@nandakrpp, I am not aware of such an issue. It's a bit surprising, with the RTC using the I2C bus and the SD card using the SPI bus, I wouldn't think there would be a lot of opportunity for clashing. Be sure that interrupts are not disabled, else the Wire library will not work. If there is a demonstrable issue with the library, please submit a SSCCE.

[nandakrpp]

@JChristensen, you are absolutely right. The problem is not between RTC's I2C and SD's SPI buses. I found out that the Ardafruit BMP180 (used with BMP085 library), another I2C device on the same bus has caused the problem. A strange thing is that there is also another I2C device on the same bus – TSL2591 that works just fine with the RTC library. Both sensors are initialised and called to read data one after another after the Wire library is started.

void setup()
{
  // initialise Wire library
  // initialise BMP library
  // initialise TSL2591 library
  // initialise RTC and set time for alarm 1 
}

void alarmIsr()
{
  alarmIsrWasCalled = true;
}

void loop()
{
 if (alarmIsrWasCalled)
  {
    if (RTC.alarm(ALARM_1))
    {
      printDateTime( RTC.get() );
      Serial << " --> Alarm 1!" << endl;
    }
    // read BMP sensor
    // read TLS2591 sensor
    // write sensor data to SD card
    alarmIsrWasCalled = false;
  }
  // put MCU to sleep
}

Without initialising BMP, everything works fine together. Any pointer to solve this problem is much appreciated.

Thanks.