SOLVED - DTC Lib - detecting missing temp sensor?

Other Hardware Sensors
1

Is there an elegant way to detect an unplugged sensor using the Dallas Temperature Control library? Multiple calls to getDeviceCount() always return the value from the very first call....subsequent calls do not seem to actually force a recheck. I have been querying each device to see if it answers but it is just a workaround solution and far from ideal. The next step is to mess with the source but I thought I'd put it out there first.

Thanks in advance.

2

Devices are counted in the begin() statement and thereafter you get a cached value.. SO if you call begin again you get a proper recount

relevant snippet of the lib

// initialize the bus
void DallasTemperature::begin(void)
{
  DeviceAddress deviceAddress;

  _wire->reset_search();
  devices = 0; // Reset the number of devices when we enumerate wire devices

  while (_wire->search(deviceAddress))
  {
    if (validAddress(deviceAddress))
    {
      if (!parasite && readPowerSupply(deviceAddress)) parasite = true;

      // ScratchPad scratchPad;

      readScratchPad(deviceAddress, scratchPad);

	  bitResolution = max(bitResolution, getResolution(deviceAddress));

      devices++;
    }
  }
}

// returns the number of devices found on the bus
uint8_t DallasTemperature::getDeviceCount(void)
{
  return devices;
}
3

I should have looked at the code before posting. Thank you for your time.

4

You are welcome,

The strong part of open source like arduino is that you can really look into the code, it might take some time to get used to that :slight_smile: