PXD20RM Datasheet, PDF (1460/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

Now the result of the back EMF integration over the time set with the BLNCNTLD register value
can be read from the ITGACC register.
9. End of Measurement
Depending from the result of the measurement the SSD block now can be disabled by clearing the
RTZE bit or another measurement can be started. Any additional measurement should start from
step 2.
42.4.3 Additional Modes of Operation
There are several additional modes how the SSD block can operate with the SM coils. They are aside from
the main use case.
42.4.3.1 Blanking with No Drive
During blanking of one coil (refer to step 3 in Section 42.4.2, Stepper Stall Detection Measurement) the
user can disable the drive of the other coil by not setting the BLNDCL bit. Since the SM has moved in the
integration phase of the previous BIS this means that the SM movement is interrupted during blanking.
This mode is not useful for SSD.
42.4.3.2 Integration with No Drive
If the ITGDCL bit is switched off the driving coil of the SM is not powered during the integration phase,
the SM will not move. Only the -modulator output is integrated with the reference voltage setting
belonging to that step. This mode makes no sense for stall detection, but it can be used for certain
measurements of the analog sub blocks.
42.5 Initialization Information
42.5.1 Analog Block Startup Time
No specific initialization after a hard reset or after leaving one of the power down modes is necessary, but
the user should allow a sufficient startup time of the analog block after hard reset or enabling of the SSD
block to compensate switching transients. The startup time specified for the analog block is 20 s.
42.5.2 Analog Block Polarity Switching Time
If the offset cancellation is used the polarity of the back EMF measurement in the analog block is reverted
during the integration phase. Note that the time for the -modulator to achieve a stable output depends
strongly from the external circuitry, e.g. coil inductance, parasitic capacitance of the leads.
As an initial estimation for typical applications a time of maximum 10 s should be taken into account by
the user.
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PXD20 Microcontroller Reference Manual, Rev. 1