IMO i3C Lite, User Manual, Page: 93 / 167

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12.3.4 Quadrature
Two HSC inputs are consumed for each of the two possible Quadrature counters. For example,
selecting quadrature mode for HSC 1 will use HSC inputs 1 and 2, which correspond to A and B
quadrature signals. Therefore, HSC 1 and 3 may be configured for quadrature input. Alternately, HSC
3 may be configured to reset HSC1 (quadrature) count on a marker input
Quadrature mode works much like the totalizer except the accumulator will automatically increment
or decrement based on the rotation phase of the two inputs. See the following example for more
details. Quadrature inputs are typically used for reporting the value of an encoder.
Two modes are available for quadrature that select whether the accumulator counts up or down when
the phase of input 1 leads input 2.
Check your encoder’s documentation to determine the output form
it uses or try both modes to determine if the encoder counts up when expected.
Using the above waveforms and an HSC input configuration of “Quadrature” - “1 leads 2, count up,”
the accumulator will count up when 1 is rising and 2 is low, 1 is high and 2 is rising, 1 is falling and 2 is
high, and when 1 is low and 2 is falling. This results in 4 counts per revolution. To determine the
number of cycles, the accumulator would have to be divided by 4.
90° phase
shift
1
(leading)
2
(lagging)