Datasheet

TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
145/230
© 2015 TRINAMIC Motion Control GmbH & Co. KG, Hamburg, Germany — Terms of delivery and rights
to technical change reserved. Download newest version at: www.trinamic.com .
Read entire documentation; especially the “Supplemental Directives” on page 224.
 MAIN MANUAL 
Incremental ABN Encoder Settings
Incremental ABN encoders increment or decrement the external position counter register
ENC_POS 0x50. This is based on A- and B-signal level transitions.
The external position register ENC_POS 0x50 is based on internal microsteps. Thus,
every AB transition is transferred to microsteps by a fixed constant value. TMC4361A
is able to calculated this constant automatically.
In order to configure the incremental ABN 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 – the number of AB transitions during one revolution - 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
This constant is the number of microsteps through which ENC_POS is incremented or
decremented by one AB transition.
i ENC_CONST consists of 15 digits and 16 decimal places.
i In case 16 bits are not sufficient for a binary representation of the decimal places,
TMC4361A tries to match them to a multiple of 10000 within these 16 decimal
places. Thereby, a perfect match can be achieved in case decimal representation
is preferred to a binary one.
i In case the decimal representation also does not fit completely, the type of the
decimal places of ENC_CONST can be selected manually with ENC_IN_CONF (0).
Set ENC_IN_CONF (0) to 0 for binary representation; or set it to 1 for the decimal
one. Keep in mind that with this approach ENC_POS can slightly differ from the
real position; especially the further away the position moves from 0.
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 incremental ABN encoder constant manually, do
as follows:
Action:
 Set ENC_IN_RES (31) =1.
 Set ENC_IN_CONF (0) to 0 for a binary or to 1 for a decimal representation as
explained in the previous section.
 Set required encoder resolution in ENC_IN_RES (30:0) register 0x54.
Result:
ENC_CONST consists of 15 digits and 16 decimal places. The constant is the number
of microsteps by which ENC_POS is incremented or decremented by one
AB transition.
Automatic
Constant
Configuration of
Incremental ABN
Encoder
Manual Constant
Configuration of
Incremental ABN
Encoder