AvaLAN Wireless AW900mSPI-10 - Manual (Page 21)

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AW900mSPI User’s Manual
b7 b6 b5 b4 b3 b2 b1 b0
Byte 2 BASE7 BASE6 BASE5 BASE4 BASE3 BASE2 BASE1 BASE0
Byte 3 BASE15 BASE14 BASE13 BASE12 BASE11 BASE10 BASE9 BASE8
BASE is a 16-bit integer constant that provides the index offset for establishing the
RF frequency. For the AW900mSPI, this value is 1688.
b7 b6 b5 b4 b3 b2 b1 b0
Byte 4 NUM7 NUM6 NUM5 NUM4 NUM3 NUM2 NUM1 NUM0
Byte 5 DEN7 DEN6 DEN5 DEN4 DEN3 DEN2 DEN1 DEN0
NUM and DEN are 8-bit integer constants used to calculate the frequency value cor-
responding to each index step. For the AW900mSPI, NUM = 25 and DEN = 48.
Frequency in MHz = (Index + BASE) * NUM / DEN
Where Index is an integer value starting with zero. For example, the lowest trans-
mit channel for the AW900mSPI corresponds to an Index of 46:
(46 + 1688) * 25 / 48 = 903.125 MHz
b7 b6 b5 b4 b3 b2 b1 b0
Byte 6 MAX7 MAX6 MAX5 MAX4 MAX3 MAX2 MAX1 MAX0
MAX is an 8-bit integer constant that represents the number of RF channels that
the radio uses. For the AW900mSPI, this value is 12. It is important to save this
number because it tells you how many bytes of data to read next:
b7 b6 b5 b4 b3 b2 b1 b0
Byte 7 MK7 MK6 MK5 MK4 MK3 MK2 MK1 MK0
Byte 8 MK15 MK14 MK13 MK12 MK11 MK10 MK9 MK8
... Repeat MAX times to read all the values
MK is a 16-bit integer that contains the Index value for each RF channel. Bytes 7
and 8 will repeat until MAX values have been read. (For the AW900mSPI, this will
total 24 bytes, Byte7 through Byte30.)
b7 b6 b5 b4 b3 b2 b1 b0
Byte 31 DP7 DP6 DP5 DP4 DP3 DP2 DP1 DP0