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11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
When writing 0 in the QDEN field of the TC_BMR register, the quadrature decoder logic is totally
transparent.
TIOA0 and TIOB0 are to be driven by the 2 dedicated quadrature signals from a rotary sensor
mounted on the shaft of the off-chip motor.
A third signal from the rotary sensor can be processed through pin TIOB1 and is typically dedi-
cated to be driven by an index signal if it is provided by the sensor. This signal is not required to
decode the quadrature signals PHA, PHB.
TCCLKS field of TC_CMR channels must be configured to select XC0 input (i.e. 0x101).
TC0XC0S field has no effect as soon as quadrature decoder is enabled.
Either speed or position/revolution can be measured. Position channel 0 accumulates the edges
of PHA, PHB input signals giving a high accuracy on motor position whereas channel 1 accumu-
lates the index pulses of the sensor, therefore the number of rotations. Concatenation of both
values provides a high level of precision on motion system position.
In speed mode, position cannot be measured but revolution can be measured.
Inputs from the rotary sensor can be filtered prior to down-stream processing. Accommodation
of input polarity, phase definition and other factors are configurable.
Interruptions can be generated on different events.
A compare function (using TC_RC register) is available on channel 0 (speed/position) or chan-
nel 1 (rotation) and can generate an interrupt by means of the CPCS flag in the TC_SR
registers.
Summary of Contents for SAM4S Series
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