S912XHZ512F1VAG Datasheet, PDF (473/978 Pages) Freescale Semiconductor, Inc – Covers MC9S12XHZ384, MC9S12XHZ256

Chapter 12 Stepper Stall Detector (SSDV1) Block Description
12.4.1.3 Conversion
In conversion mode, one of the coils is routed for integration with one end connected to the (non-zero)
reference input and the other end connected to the integrator input of the sigma-delta converter. If RTZ is
enabled (RTZE=1), both coils are disconnected. This mode is not useful for stall detection.
12.4.1.4 Integration
In integration mode, one of the coils is routed for integration with one end connected to the (non-zero)
reference input and the other end connected to the integrator input of the sigma-delta converter. If RTZ is
enabled (RTZE = 1), the other coil is driven. This mode is used to rectify and integrate the back EMF
produced by the coils to detect stepped rotary motion.
DC offset compensation is implemented when using the modulus down counter to monitor integration
time.
12.4.2 Full Step States
During a return to zero (RTZ) event, the stepper motor pointer requires a 90° full motor electrical step with
full amplitude pulses applied to each phase in turn. For counter clockwise rotation (CCW), the STEP value
is incremented 0, 1, 2, 3, 0 and so on, and for a clockwise rotation the STEP value is decremented 3, 2, 1,
0 and so on. Figure 12-10 shows the current level through each coil for each full step in CCW rotation
when DCOIL is set.
SINE COIL
CURRENT
+ Imax
0
_ _Imax
Recirculation
+ Imax
COSINE COIL
CURRENT
0
_ _Imax
0
1
2
3
Figure 12-10. Full Steps (CCW)
Figure 12-11 shows the current flow in the SINx and COSx H-bridges when STEP = 0, DCOIL = 1,
ITG = 0 and RCIR = 0.
MC9S12XHZ512 Data Sheet, Rev. 1.06
Freescale Semiconductor
473