mc9s12hz256v2 Freescale Semiconductor, Inc, mc9s12hz256v2 Datasheet - Page 299

• Manufacturer Part Number: mc9s12hz256v2
• Description: Hcs12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

10.3.2.4
Read: anytime
Write: anytime.
Freescale Semiconductor
l
ACLKS
Reset
MCZIF
AOVIF
FTST
Field
Field
1:0
4
7
0
W
R
MCZIF
Factory Test — This bit is reserved for factory test and reads zero in user mode.
Accumulator Sample Frequency Select — This field sets the accumulator sample frequency by pre-scaling
the bus frequency by a factor of 8, 16, 32, or 64. A faster sample frequency can provide more accurate results
but cause the accumulator to overflow. Best results are achieved with a frequency between 500 kHz and 2 MHz.
Modulus Counter Underflow Interrupt Flag — This flag is set when the modulus down-counter reaches
0x0000. If not masked (MCZIE = 1), a modulus counter underflow interrupt is pending while this flag is set. This
flag is cleared by writing a ‘1’ to the bit. A write of ‘0’ has no effect.
Accumulator Overflow Interrupt Flag — This flag is set when the Integration Accumulator has a positive or
negative overflow. If not masked (AOVIE = 1), an accumulator overflow interrupt is pending while this flag is set.
This flag is cleared by writing a ‘1’ to the bit. A write of ‘0’ has no effect.
Stepper Stall Detector Flag Register (SSDFLG)
0
7
A change in the accumulator sample frequency will not be effective until the
ITG bit is cleared.
= Unimplemented or Reserved
ACLKS
Figure 10-5. Stepper Stall Detector Flag Register (SSDFLG)
0
1
2
3
0
0
6
Table 10-8. SSDCTL Field Descriptions (continued)
Table 10-9. Accumulator Sample Frequency
Table 10-10. SSDFLG Field Descriptions
Frequency
f
f
f
f
BUS
BUS
BUS
Accumulator Sample Frequency = f
MC9S12HZ256 Data Sheet, Rev. 2.05
BUS
0
0
5
/ 16
/ 32
/ 64
/ 8
f
5.00 MHz
2.50 MHz
1.25 MHz
NOTE
BUS
625 kHz
0
0
4
MHz
= 40
Description
Description
f
3.12 MHz
1.56 MHz
781 kHz
391 kHz
BUS
0
0
3
MHz
BUS
= 25
/ (8 x 2
Chapter 10 Stepper Stall Detector (SSDV1)
0
0
2
2.00 MHz
1.00 MHz
f
ACLKS
500 kHz
250 kHz
BUS
MHz
= 16
)
0
0
1
AOVIF
0
0
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