Datasheet

TMC8460-BI Datasheet (V1.00 / 2016-Sep-01)
Copyright © 2016 TRINAMIC Motion Control GmbH & Co. KG 130
6.8 MFCIO Step Direction Unit
The MFC is equipped with a step-direction unit. Programming of the step pulse frequency occurs by
writing an accumulation constant to a register. Toggle of the MSB of the accumulation register value
generates an internal step pulse of one internal clock cycle. The direction signal is the MSB of the
accumulation constant. Therefore, the sign of the accumulation constant defines the direction signal
polarity. The step-to-direction timer (STP2DIR) takes care of possible external signal delay paths by
programmable delay of the first step after write of accumulation constant. The pulse stretcher forms
step and direction pulses of programmable length for adaption to external signal paths. The step
direction unit can either run in free running mode just generating step pulses with programmed
frequency. Alternatively, is can generate a defined number of step pulses with programmed frequency.
An interrupt output signal IRQ_TARGET_REACHED indicates the reached target count of step pulses.
Figure 33 - Step Direction Unit Block Diagram
2.1.1 Step Direction Unit Timing
Write to the accumulation constant register starts step pulse generation. The first step pulse occurs
after a time tSTEP1st. Following step pulses come after each tSTEP. The pulse length of the step pulses
is iSTEP_PULSE. On change of direction by writing the accumulation constant with a constant of different
sign, the first step pulse after write occurs after tSTP2DIR.
Figure 34 - Step-Direction Timing