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GLOBALSTAR PROPRIETARY AND CONFIDENTIAL INFORMATION
Use or disclosure of data contained on this sheet is subject to the restrictions in the Distribution Statements on the title page of this
document.
06/18/20 Subject to Change without Notice P a g e | 26
4.2.1 Serial Packet Format
Preamble
Fixed pattern 0xAA
Length
Total number of bytes in the serial packet including the preamble
Command
Command type (See Table 5 Serial Packet Type). Responses to
commands carry the same command type as the command that
initiated the answer
Data
Data associated with the command or answer
CRC
16 bit CRC
Figure 4 Serial Packet Format
4.2.2 Serial Packet Command List
For all serial packet commands as described below:
• AA is the Preamble.
• NN is the Length.
• XX is an unspecified byte value
• CLSB is the least significant CRC byte
• CMSB is the most significant CRC byte
• CLSB and CMSB are omitted when using the RAW command. Length must still be specified to include them,
however.
• If an improperly formatted command is received, the ST100 BOARD will return a NAK response:
AA 05 FF A1 CB
4.2.2.1 Send Data (0x00)
The Send Data command requests the ST100 board to send from 1 to 144 data bytes over the Globalstar Simplex
network.
0x00
Leader
Len
Cmd
payload
1
payload
2
payload
3
..
payload
N
CRC1
CRC2
AA
NN
00
XX
XX
XX
XX
XX
CLSB
CMSB
Example Command: AA 0E 00 01 02 03 04 05 06 07 08 09 BE E8
Length
(1 byte)
Preamble
(1 byte)
Command
(1 byte)
Data
(variable length)
CRC
(2 bytes)