MC9S12HZ128VAL Datasheet, PDF (295/692 Pages) Freescale Semiconductor, Inc – MC9S12HZ256 Data Sheet, Rev. 2.05

10.3.2.1 Return-to-Zero Control Register (RTZCTL)
Chapter 10 Stepper Stall Detector (SSDV1)
7
6
5
4
3
2
R
0
ITG
DCOIL
RCIR
POL
SMS
W
Reset
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 10-2. Return-to-Zero Control Register (RTZCTL)
1
0
STEP
0
0
Read: anytime
Write: anytime
Table 10-3. RTZCTL Field Descriptions
Field
7
ITG
6
DCOIL
5
RCIR
4
POL
2
SMS
1:0
STEP
Description
Integration — During return to zero (RTZE = 1), one of the coils must be recirculated or non-driven determined
by the STEP field. If the ITG bit is set, the coil is non-driven, and if the ITG bit is clear, the coil is being recirculated.
Table 10-4 shows the condition state of each transistor from Figure 10-1 based on the STEP, ITG, DCOIL and
RCIR bits.
Regardless of the RTZE bit value, if the ITG bit is set, one end of the non-driven coil connects to the (non-zero)
reference input and the other end connects to the integrator input of the sigma-delta converter. Regardless of
the RTZE bit value, if the ITG bit is clear, the non-driven coil is in a blanking state, the converter is in a reset state,
and the accumulator is initialized to zero. Table 10-5 shows the condition state of each switch from Figure 10-1
based on the ITG, STEP and POL bits.
0 Blanking
1 Integration
Drive Coil — During return to zero (RTZE=1), one of the coils must be driven determined by the STEP field. If
the DCOIL bit is set, this coil is driven. If the DCOIL bit is clear, this coil is disconnected or drivers turned off.
Table 10-4 shows the condition state of each transistor from Figure 10-1 based on the STEP, ITG, DCOIL and
RCIR bits.
0 Disconnect Coil
1 Drive Coil
Recirculation in Blanking Mode — During return to zero (RTZE = 1), one of the coils is recirculated prior to
integration during the blanking period. This bit determines if the coil is recirculated via VDDM or via VSSM.
Table 10-4 shows the condition state of each transistor from Figure 10-1 based on the STEP, ITG, DCOIL and
RCIR bits.
0 Recirculation on the high side transistors
1 Recirculation on the low side transistors
Polarity — This bit determines which end of the non-driven coil is routed to the sigma-delta converter during
conversion or integration mode. Table 10-5 shows the condition state of each switch from Figure 10-1 based on
the ITG, STEP and POL bits.
Stepper Motor Select — This bit selects one of two possible stepper motors to be used for stall detection. See
top level chip description for the stepper motor assignments to the SSD.
0 Stepper Motor A is selected for stall detection
1 Stepper Motor B is selected for stall detection
Full Step State — This field indicates one of the four possible full step states. Step 0 is considered the east pole
or 0° angle, step 1 is the north Pole or 90° angle, step 2 is the west pole or 180° angle, and step 3 is the south
pole or 270° angle. For each full step state, Table 10-6 shows the current through each of the two coils, and the
coil nodes that are multiplexed to the sigma-delta converter during conversion or integration mode.
MC9S12HZ256 Data Sheet, Rev. 2.05
Freescale Semiconductor
295