Freescale Semiconductor Demonstration Board for Freescale MC9S12XHY256 Microcontroller DEMO9S12XHY256 DEMO9S12XHY256 用户手册

Freescale Semiconductor

711

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.

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.

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.

 shows the current level through each coil for each full step in CCW rotation

when DCOIL is set.

 shows the current flow in the SINx and COSx H-bridges when STEP = 0, DCOIL = 1,

ITG = 0 and RCIR = 0.

0

1

2

3

0

Imax

+

_

Imax

0

Imax

+

_

Imax

SINE COIL
CURRENT

COSINE COIL
CURRENT

Recirculation