User Manual

PD28-1-1021 / PD28-3-1021 V1.4 Hardware Manual (Rev. 1.03 / 2018-JAN-25) 9
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3.3 Integrated sensOstep™ encoder
The PD28-1-1021 and PD28-3-1021 PANdrive offer integrated sensOstep™ encoders based on hall sensor
technology. As the name “sensOstep™” already indicates intended use of this type of compact and highly
integrated encoder is step loss detection of motor movements. As soon as the motor has been moved to
a new location the position may be verified using this encoder feedback. In case the stepper motor has
lost one or multiple steps during movement e.g. due to overload / any obstacle encountered during
movement the motor axes will jump for at least one electrical period / 4 full steps. This can be detected
using the integrated encoder. In addition, step losses may be already detected during motor movements
using the “deviation” setting available as part of the TMCL firmware (see TMCM-1021 firmware manual for
more details).
While the encoder offers 10bit (1024 steps) resolution per motor revolution the absolute position
information is less accurate and depends on the displacement of the hall sensor based encoder IC relative
to the magnet and motor axis among other factors. Every PANdrive™ has been tested for maximum
deviation of +/- 5 encoder steps (static performance) relative to commanded microstep target position
during final tests after assembly at our factory. This will ensure more than adequate performance of the
integrated sensOstep™ encoder for step loss detection during motor movements.
Do not disassemble PANdrive™ when using integrated encoder
In order to make proper use of the integrated sensOstep™ encoder (the sensor IC is placed
on the bottom center of the pcb) the TMCM-1021 electronics should not be removed/moved
relative to the motor! Otherwise encoder performance might suffer / not work.
Note: In case the integrated encoder feature is not used, the TMCM-1021 electronics may
be moved or even removed from the motor and placed somewhere else according to
application requirements.
Keep the electronics free of (metal) particles!
The integrated sensOstep™ encoder uses a magnet at the end of the motor axis in order
to monitor position of the motor axis. The magnet naturally attracts especially tiny metal
particles. These particles might be held on the top side of the PCB and even worse – start
moving in accordance with the rotating magnetic field as soon as the motor starts moving.
This might lead to shorts of electronic contacts / wires on the board and totally erratic
behavior of the module! Use compressed air for cleaning the module if necessary
(especially in prototype setups).
In order to prevent shorts and better protect the electronics the TMCM-1021 printed circuit
board is coated after assembly of components since hardware version V1.4.