Datasheet

TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
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Read entire documentation; especially the “Supplemental Directives” on page 224.
 MAIN MANUAL 
The external position register ENC_POS 0x50 is based on internal microsteps. Thus,
every input data angle is transferred to microsteps by a fixed constant value.
TMC4361A is able to automatically calculate this constant.
In order to configure the absolute encoder constant automatically, do as
follows:
Action:
 Set fullstep resolution of the motor in FS_PER_REV ( STEP_CONF register 0x0A).
 Set microstep resolution MSTEP_PER_FS ( STEP_CONF register 0x0A).
 Set encoder resolution in register ENC_IN_RES 0x54 (write access).
Result:
The encoder constant value ENC_CONST (readable at register 0x54) is calculated as
follows:
ENC_CONST = MSTEP_PER_FS · FS_PER_REV / ENC_IN_RES
The external position ENC_POS 0x50 is calculated by multiplying the constant with the
transmitted input angle.
i ENC_CONST consists of 15 digits and 16 decimal places.
i In contrast to incremental ABN encoders, ENC_CONST is always represented as
binary constant.
For some applications it can be useful to define the encoder constant value, which in
this case does not correspond to the number of microsteps per revolution;
e.g. if the encoder is not mounted directly on the motor.
In order to configure the absolute encoder constant manually, do as
follows:
Action:
 Set ENC_IN_RES (31) =1.
 Set required encoder resolution in ENC_IN_RES (30:0) register 0x54.
Result:
ENC_CONST consists of 15 digits and 16 decimal places. The external position
ENC_POS 0x50 is calculated by multiplying the constant with the transmitted input
angle.
Automatic
Constant
Configuration of
Absolute
Encoder
Manual Constant
Configuration of
incremental ABN
Encoder