Datasheet

TMC4361A Datasheet | Document Revision 1.22 • 2017-JAN-12
52/230
© 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 
DIRIN polarity can be assigned. Per default, the negative direction is indicated by
DIRIN = 0.
In order to change this polarity:
Action:
 Set pol_dir_in = 1 ( GENERAL_CONF register 0x00).
Result:
A negative input direction is assigned by DIRIN = 1.
If an external step is not congruent with an internal step, the GEAR_RATIO register
0x12 must be set accordingly. This signed parameter consists of eight bit digits and
24 bits decimal places.
With every external step the assigned GEAR_RATIO value is added to an internal
accumulation register. As soon as an overflow occurs, an internal step is generated
and the remainder will be kept for the next external step.
Any absolute gearing value between 2
-24
and 127 is possible.
NOTE:
 Gearing ratios beyond 1 are more reasonable for the SPI output. The internal
SinLUTable is used that generates multiple steps one after another without
interpolation, if the accumulation register value is above 1. In contrast to a burst
of steps at the STPOUT pin, the SPI output will only forward the new position in
the inner SinLUT where only some values have been skipped if |GEAR_RATIO|>1.
 A negative gearing factor GEAR_RATIO < 0 inverts the interpretation of the input
direction which is determined by DIRIN and pol_dir_in .
It is possible to use the internal ramp generator in combination with the external S/D
interface.
In this case, the external step impulses transferred via STPIN and DIRIN cannot
influence the internal XACTUAL counter directly. Instead, the XTARGET register is
altered by 1 or -1 with every GEAR_RATIO accumulation register overflow.
NOTE:
 Whether XTARGET is increased or decreased is determined similarly to the direct
electronic gearing control. The accumulation register overflow direction indicates
the target alteration. Respectively, the accumulation direction is determined by
the GEAR_RATIO sign, by pol_dir_in, and by DIRIN.
 Consecutive input steps must occur with a distance of minimum 64 clock cycles.
i This feature allows a synchronized motion of different positioning ramps for
different TMC4361A chips with differently configured ramps.
In order to select indirect external control, do as follows:
Action:
 Set sdin_mode ≠ b’00 according to the required external control option.
 Set sd_indirect_control = 1 ( GENERAL_CONF register 0x00).
Result:
As soon as an external step is generated, XTARGET is increased or decreased,
according to the accumulation direction.
Selecting the
Input Direction
Polarity
Description of
Electronic
Gearing
Indirect
External Control