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11.5.1 Almanac Full Update
The Almanac data for all the satellites can be updated using the command GnssAlmanacFullUpdate( ) :
Table 11-16: GnssAlmanacFullUpdate
Byte
Data from Host
Data to Host
•
AlmanacFullUpdatePayload: defined as in
Table 11-17: AlmanacFullUpdatePayload
Byte
Field
AlmanacHeader
•
With the AlmanacHeader defined as in
Table 11-18: AlmanacHeader
Byte
Field
•
Each SvAlmanac being a 20 Bytes structure, defined as
Table 11-19: SvAlmanac Format
Byte
Field
It is up to the user to ensure that the list of almanacs and the list of satellites ids are coherent. The Almanac data must be
provided in the same order as satellite ids.
The AlmanacFullUpdatePayload takes 20 Bytes (Header) +128 (number of SV) * 20 Bytes =2580 Bytes.
The maximum number of Bytes that can be send from the host MCU is 1020 Bytes. Therefore, the Almanac Full Update shall
be handled in multiple SPI transactions. For example, the two following approaches are possible:
•
minimum memory overhead:
The AlmanacFullUpdatePayload can be sent in 129 successive SPI transactions of 20 data Bytes each.
•
minimum number of SPI transactions:
The AlmanacFullUpdatePayload can be sent in 2 SPI transactions of 1020 data Bytes each, and a third SPI transaction of
540 Bytes.
LR1110
User Manual
Rev.1.0
UM.LR1110.W.APP
March 2020
0
0x04
Stat1
Table 11-17: AlmanacFullUpdatePayload
(0:19)
(20:39)
SV1 Almanac
Table 11-18:
0
128
0
(1:15)
SV id
Almanac Content
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1
0x0E
Stat2
IrqStatus(31:24)
(40:56)
SV2 Almanac
AlmanacHeader:
(1:2)
AlmanacDate
Global CRC
Table 11-19: SvAlmanac
(16:17)
CA code
2
AlmanacFullUpdatePayload
:
...
(2560:2579)
...
SV128 Almanac
(3:6)
(7:19)
RFU
Format:
18
Modulation bit
Constellation Id
mask
...
...
19
103 of 130
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