Rather than counting pulses over a fixed time interval, the pulse meter sensor measures the time between pulses. The precise manner in which this is done depends on the ``internal_filter_mode`` option. This leads to a higher resolution, especially for low pulse rates, as the pulse counter sensor is limited by the number of pulses within a time interval.
Here's a comparison of the two sensors. The pulse meter is the smoother line. Both are set to an update interval of 10 seconds (using the ``update_interval`` and the ``throttle_average`` option respectively):
One of ``EDGE`` or ``PULSE``. Defaults to ``EDGE``.
- In ``EDGE`` mode, subsequent rising edges are compared and if they fall into an interval lesser than the ``internal filter`` value, the last one is discarded. This is useful if your input signal bounces, but is otherwise clean.
- In ``PULSE`` mode, the rising edge is discarded if any further interrupts are detected before the ``internal_filter`` time has passed. In other words, a high pulse must be at least ``internal_filter`` long to be counted. This is useful if you have a noisy input signal that may have bounces before and/or after the main pulse.
The sensor defaults to units of *pulses/min*, You can change this by using :ref:`sensor-filters`.
For example, if you’re using the pulse meter with a photodiode to count the light pulses on a power meter that has an impulse constant of *10000 pulses / kWh*, you can use the following to output instantaneous usage in *W*:
