TMC428_06 Datasheet, PDF(23/58 Page) List of Unclassifed Manufacturers – Intelligent Triple Stepper Motor Controller with Serial Peripheral Interfaces

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

TMC428_06 Datasheet, PDF (23/58 Pages) List of Unclassifed Manufacturers – Intelligent Triple Stepper Motor Controller with Serial Peripheral Interfaces

◁

TMC428 DATASHEET (v. 2.02 / April 26th, 2006)

used as automatic stop switches as well. Per default, one reference switch input is assigned

individually to each stepper motor as a left reference switch (see Figure 9-3, page 32). The reference

switch input REF3 can alternatively be assigned as the right reference switch of stepper motor number

one (see Figure 9-4, page 32). In that configuration a left and a right reference switch is assigned to

stepper motor one, a left reference switch is assigned to stepper motor two, and no reference switch is

assigned to stepper motor three. The bit named mot1r in the stepper motor global parameter register

(rrs=1 & address=%111111) selects one of these configurations. With additional hardware, up to six

reference switchesâ a left and a right one assigned to each stepper motor âare supported. The

additional hardware is just a 74HC157, where three of four 2-to-1-multiplexers are used (see Figure

9-5, page 32). The feature of multiplexing is controlled by the bit named refmux in the stepper motor

global parameter register (rrs=1 & address=111111).

A reference switch can be used as an automatic stop switch. The reference switch indicates the

reference position within a given tolerance. The automatic stop function of the switches can be enabled

or disabled. Also a reference tolerance range (see register dx_ref_tolerance, page 27) can be

programmed, to allow motion within the reference switch active range during reference point search.

When a reference switch is triggered, the actual position can be stored automatically. This allows

precise determination of the reference point. This is initiated by writing a dummy value to register

x_latched (see page 27). The read-only status bit lp (latch position waiting) then indicates that the next

active edge at the selected reference switch will trigger latching the position x_actual. The lp bit is

automatically reset after position latching.

left switch

motor

right switch

negative direction

traveller

x1 xleft x2

xtraveler

x3 xright x4

mechanical inaccuracy of switches

(switching hysteresis)

positive direction

dx_ref_tolerance

Figure 8-4: Left switch and right switch for reference search and automatic stop function

ref_conf mnemonic

DISABLE_STOP_L

DISABLE_STOP_R

SOFT_STOP

REF_RnL

function

0 : Stops a motor if velocity is negative (v_actual < 0) and the left reference switch becomes

active.

1 : Left reference switch is disabled as a an automatic stop switch.

0 : Stops a motor if velocity is positive (v_actual > 0) and the right reference switch becomes

active.

1 : Right reference switch is disabled as an automatic stop switch.

0 : Stopping takes place immediately, motion parameter limits are ignored.

1 : Stopping takes place in consideration of motion parameter limits, stops with linear ramp.

0 : The left reference switch controls reference switch functions.

1 : The right (not left) reference switch controls reference switch functions.

0 : This is the power-on default of the lp (latched position waiting) bit.

1 : A write access initialized x_latched to latch the position if the reference switch becomes active.

It is set to â0â after a position is latched.

Table 8-4: Reference switch configuration bits (ref_conf)

Note: Definition of the reference switch by the configuration bit REF_RnL has no effect on the stop

function of the reference switches if DISABLE_STOP_L=â0â respectively DISABLE_STOP_R=â0â. The

▷