Sorry for the delay on this one.
Sampling on the meter works as follows. I capitalize variables that you can set through the app:
For one reading, the meter takes BUFFER_DEPTH readings at SAMPLE_RATE. Then it performs math on them (mean for DC readings, RMS for AC readings). It sends the result to the phone if you’re connected, or to the log if this reading was triggered by the log timer.
The log timer goes off once every LOG_INTERVAL. The settings available through the app are 10minutes, 1minute, 10s, 1s and MAX (0s).
If you set the logging interval to MAX(0), the meter will take readings and write them to the SD card as fast as possible. The actual rate you’ll get depends on the SAMPLE_RATE and BUFFER_DEPTH you set. So if you set 125Hz, 32samples, you’d end up writing to the log at about 4Hz (125/32).
If you want to go faster, try raising the sample rate and lowering the buffer depth. If you set it to 4000Hz, 32 samples, you’d expect to write to the log at about 125Hz (4000/32). The number you actually see in the log might be slightly slower if the SD card becomes a bottleneck, but it should be pretty close (the Mooshimeter doesn’t write very quickly compared to cameras and other peripherals that SD cards are meant for).
I hope this helps, best