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G.FIT User Guide and Specification, Rev 2.0_Alpha.14
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Command/Response
Request/Command
Events
MCU
MCU
MCU
MCU
Command/Response
Request/Command
Events
MCU
MCU
Figure 7-2. Extended serial message types
7.1.1
Commands (0xE2)
Extended serial commands are used to execute specific commands on G.FIT, or to provide information about
the settings/state of G.FIT. When sent by the application MCU they elicit a response from G.FIT. If a message
request is made by the application MCU, then G.FIT will send a comman d message in response.
The structure of a command is identical to that described by Figure 7-1, with the extended message type set
to 2. The specific command to execute is indicated by the second byte of the message ID (sub-message ID).
The payload is specific to each command and may be completely empty. Figure 7-3 shows an extended serial
command.
1 byte
1 byte
1 byte
1 byte
X byte
1 byte
Sync
Length
Message ID
Payload
0xE2
Sub Message ID
Figure 7-3. Extended serial command
7.1.2
Requests (0xE1)
Extended serial requests are used by the application MCU to request information from G.FIT. The information
requested comes to the MCU in the form of a command.