3.2 Harmonic Analysis
Harmonic analysis control-related registers are allocated in the HARMONIC_CTRL and FEATURE_CTRL.
The HARMONIC_CTRL.HARMONIC_EN (bit 31) enables or disables harmonic computation. The 0 to 30 bits are used to select the specific harmonics to be computed. Accurate results from the analysis are obtained after a complete integration period has elapsed. Therefore, the application must disregard the results generated during the integration period in which the analysis was enabled or the harmonic selection was modified.
The FEATURE_CTRL register allows the selection of channels enabled for harmonic computation. By default, all channels are enabled.
Warning: Although the control register can enable up to 31
harmonic orders, the frequency response may be limited by the metrology filters or the
input network anti-aliasing filters. With respect to the metrology filters, the accuracy
is better than 0.007% up to 1386 Hz, ensuring an extremely accurate response up to the
21st harmonic order (considering a fundamental frequency of 60 Hz, with a 10%
deviation). However, the response remains relatively flat up to 1650 Hz, with an error
margin of up to 0.05%.
Note: When enabled, the harmonic analysis result is updated every
integration period. The INTEGRATION_IRQ will be generated at the end of the integration
period, and this interrupt can be used to update the harmonic analysis result.