TMC4671 Datasheet • IC Version V1.00 | Document Revision V1.04 • 2018-Dec-11
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Figure 23: Flux Ramping
For correct operation of this module a few parameters have to be set. Please try
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4.7.10.3 Encoder Initialization by Hall sensors
The TMC4671 can calculate PHI_E_OFFSET very precisely at a Hall state change for a second encoder
system, when Hall sensors are correctly aligned. Therefore, the function needs to be enabled and calculate
a new offset at the next Hall state change. After disabling of the module, the process can be started again.
This function can also be used as a rough plausibility check during longer operation.
4.7.10.4 Encoder Initialization by N Pulse Detection
After determination of a correct offset, the value can be used again after power cycle. The encoder’s N
pulse can be used as reference for this. For starters the user can drive the motor in open-loop mode or by
using digital Hall sensor signals. After passing the encoder’s N pulse, the ABN encoder is initialized and
can be used for operation.
4.7.11 Velocity Measurement
Servo control comprises position, velocity and current control. The position and the current are measured
by separate sensors. The actual velocity has to be calculated by time discrete differentiation from the
position signal. the user can choose a calculated position from the various encoder interfaces for velocity
measurement by parameter VELOCITY_SELECTION.
The user can switch between two different velocity calculation algorithms with the parameter VELOC-
ITY_METER_SELECTION. Default setting (VELOCITY_METER_SELECTION = 0) is the standard velocity meter,
which calculates the velocity at a sampling rate of about 4369.067 Hz by differentiation. Output value is
displayed in rpm (revolutions per minute). This option is recommended for usage with the standard PI
controller structure.
By choosing the second option (VELOCITY_METER_SELECTION = 1), the sampling frequency is synchronized
to the PWM frequency. This option is recommended for usage with the advanced PI controller structure.
Otherwise, the controller structure might tend to be unstable due to non-matched sampling.
Velocity filters can be applied to reduce noise on velocity signals. Section 4.9 describes filtering opportuni-
ties in detail.
4.7.12 Reference Switches
The TMC4671 is equipped with three input pins for reference switches (REF_SW_L, REF_SW_H and REF_SW_R).
These pins can be used to determine three reference positions. The TMC4671 displays the status of the
reference switches in the register TMC_INPUTS_RAW and is able to store the actual position at rising
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