Version 2.03 is now available.
There is no real need to update any installation using this library unless you experience large swings in the a.c. line frequency. The previous versions used mains time to calculate the energy over the reporting period: if the frequency is markedly different from the nominal value, this would lead to a corresponding error in the energy value reported. The energy calculation has been changed to use the processor clock, which removes that error. Note that the reporting interval itself is still timed using the mains clock.
The average mains frequency is now available as one of the values reported.
Note for developers: The library can now switch the ADC reference source. Details are included in the documentation. Users of the emonTx, emonPi and Arduino should not experiment with this, as damage to the processor is possible if the wrong setting is used.