LSM303 Accelerometer + Compass library integration into ModularSensors

I’m sure the LSM303 could be integrated into ModularSensors. You should also be able to use it along with ModularSensors without actually integrating it. You might not be able to use the “logData” function though – you might have to break it up some.

So, do you have your program somewhere I could look at? Are you turning off the power to the sensor between reading? (Is your I2C port set to switched power?) Are you sure the sensor is powered when you’re trying to read it? Did you try putting a begin() for the LSM303 right before it’s read? In that library it looks like the begin() function sends an activate command which it may need after every power up (or even after every time I2C is disconnected).

You definitely want to update for calculated variables. There’s a big bug in 0.19.6 in the “completeUpdate” function in run inside the “logData” function that will make any calculated variables crash.

After you update, adding the compass as a “calculated” variable should work just as you described. That is, you could call the begin and update to return a float in the calcFxn – and you would not be able to get averages or multiple readings without writing it yourself in the function. The calculated variable function are not called until after all the sensors have completed all measurements and gone to sleep.

You could look at the BME’s code if you want to try and write it as a new sensor. I need to write up better documentation on how to create a new sensor.

If you’re averaging multiple measurements, the first measurement is started stabilizationTime_ms after wake up and the result requested measurementTime_ms later, or as close to that time as the sensor is checked in iterating through all variables. The second measurement is begun in the next loop after the first measurement result is collected, so nearly immediately after the first measurement is completed. The result is requested measurementTime_ms later. Same for all subsequent measurements.

If there was only one sensor with three readings, it would go about like this:

main processsor wakes -> sensor powerUp() -> wait warmUpTime_ms -> sensor wake() -> wait stabilizationTime_ms -> startSingleMeasurement() -> wait measurementTime_ms -> addSingleMeasurementResult() -> startSingleMeasurement() -> wait measurementTime_ms -> addSingleMeasurementResult() -> startSingleMeasurement() -> wait measurementTime_ms -> addSingleMeasurementResult() -> sensor sleep() -> sensor powerDown() -> calculated variables calculated -> data written to SD -> data published to remotes -> mcu goes to sleep.

The reality is a little different if there are multiple sensors because each step takes a non-zero amount of time and the millis() function gets called a lot which in itself wastes processor time, but it shouldn’t be far off the above. If you’re seeing something much different, that’s a problem/bug.

So, right now there’s now way to average readings between multiple wake/sleep sessions. So if you wanted to average 10 readings 1 minute apart, the mcu and sensor would be awake the whole time and murder your battery. You could create two logger instances, one logging at 1 minute and another logging at 10 minutes and only attach a publisher to the longer logging interval, but the data going out would only be from that 1 measurement, not the last 10. You’d want to optimize your loop to do this; DON’T just use logData(). If you look in the definitions for the dataPublishers, there are arguments for a send frequency and offset, but those are just place-holders right now – they’re not actually implemented in any way in the code.

If you’re making a new SDI-12 sensor, you shouldn’t modify the SDI12Sensors.cpp. Create a new cpp/h pair defining a sub-class of SDI-12 sensor. Look at the Decagon5TM as an example – it follows the “normal” SDI12 sensor in everything except “addSingleMeasurementResult” which is defined separately.

You can completely ignore the error “override controls (override/final) only available with -std=c++1 or -std=gnu++11” I’m not sure why it always comes up. I can’t imagine your compiler version isn’t high enough to support it.