MC68181 Datasheet, PDF (69/119 Pages) Freescale Semiconductor, Inc – Advance Information ROAMING FLEX chip SIGNAL PROCESSOR

Freescale Semiconductor, Inc.
MC68181
Host-to-Decoder Packet Descriptions
decoding is enabled (i.e., the ON bit in the Control Packet is set). The ID of the
Configuration Packet is 1.
Byte
3
2
1
0
Table B-4 Configuration Packet Bit Assignments
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
SME
MOT
COD
MTE
LBP
0
Bit 1
0
OFD₁
SP₁
0
Bit 0
1
OFD₀
SP₀
0
OSCILLATOR FREQUENCY DIFFERENCE (OFD)
These bits describe the maximum difference in the frequency of the 76.8 kHz
oscillator crystal with respect to the frequency of the transmitter. These limits should
be the worst case difference in frequency due to all conditions, including but not
limited to aging, temperature, and manufacturing tolerance. Using a smaller
frequency difference in this packet will result in lower power consumption due to
higher receiver battery save ratios. Note that this value is not the absolute error of the
oscillator frequency provided to the FLEX chip IC. The absolute error of the clock
used by the FLEX transmitter must be taken into account. (If the transmitter tolerance
is ±25 ppm and the 76.8 kHz oscillator tolerance is ±140 ppm, the oscillator frequency
difference is ±165 ppm and OFD should be set to 0.) The value after reset = 0.
Table B-5 on page B-9 summarizes the bit definitions.
Table B-5 OFD Bits Description
OFD₁
OFD₀
Frequency
Difference
0
0
±300 ppm
0
1
±150 ppm
1
0
±75 ppm
1
1
±0 ppm
SIGNAL POLARITY (SP)
These bits set the polarity of EXTS1 and EXTS0 input signals. The value after reset = 0.
The polarity of the EXTS0 and EXTS1 bits will be determined by the receiver design.
MOTOROLA
MC68181 Technical Data Sheet
B-9
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