14.0 Integrated Firmware
The LMX9838 includes the full Bluetooth stack up to RF-
Comm to support the following profiles:
•
GAP (Generic Access Profile)
•
SDAP (Service Discovery Application Profile)
•
SPP (Serial Port Profile)
Figure 5 shows the Bluetooth protocol stack with command
interpreter interface. The command interpreter offers a num-
ber of different commands to support the functionality given
by the different profiles. Execution and interface timing is han-
dled by the control application.
The chip has an internal data area in RAM that includes the
parameters shown in Table 11.
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FIGURE 5. LMX9838 Software Implementation
14.1 FEATURES
14.1.1 Operation Modes
On boot-up, the application configures the module following
the parameters in the data area.
Automatic Operation
No Default Connections Stored:
In Automatic Operation the module is connectable and dis-
coverable and automatically answers to service requests.
The command interpreter listens to commands and links can
be set up. The full command list is supported.
If connected by another device, the module sends an event
back to the host, where the RFComm port has been connect-
ed, and switches to transparent mode.
Default Connections Stored:
If default connections were stored on a previous session,
once the LMX9838 is reset, it will attempt to connect each
device stored within the data RAM three times. The host will
be notified about the success of the link setup via a link status
event.
Non-Automatic Operation
In Non-Automatic Operation, the LMX9838 does not check
the default connections section within the Data RAM. If con-
nected by another device, it will NOT switch to transparent
mode and continue to interpret data sent on the UART.
Transparent Mode
The LMX9838 supports transparent data communication from
the UART interface to a bluetooth link.
If activated, the module does not interpret the commands on
the UART which normally are used to configure and control
the module. The packages don’t need to be formatted as de-
scribed in Table 13. Instead all data are directly passed
through the firmware to the active bluetooth link and the re-
mote device.
Transparent mode can only be supported on a point-to-point
connection. To leave Transparent mode, the host must send
a UART_BREAK signal to the module.
Force Master Mode
In Force Master mode tries to act like an access point for
multiple connections. For this it will only accept the link if a
Master/slave role switch is accepted by the connecting de-
vice. After successful link establishment the LMX9838 will be
Master and available for additional incoming links. On the first
incoming link the LMX9838 will switch to transparent depend-
ing on the setting for automatic or command mode. Additional
links will only be possible if the device is not in transparent
mode.
14.1.2 Default Connections
The LMX9838 supports the storage of up to 3 devices within
its NVS. Those connections can either be connected after re-
set or on demand using a specific command.
14.1.3 Event Filter
The LMX9838 uses events or indicators to notify the host
about successful commands or changes at the bluetooth in-
terface. Depending on the application the LMX9838 can be
configured. The following levels are defined:
•
No Events:
– The LMX9838 is not reporting any events. Optimized for
passive cable replacement solutions.
•
Standard LMX9838 events:
– Only necessary events will be reported.
•
All events:
– Additional to the standard all changes at the physical
layer will be reported.
14.1.4 Default Link Policy
Each Bluetooth Link can be configured to support M/S role
switch, Hold Mode, Sniff Mode and Park Mode. The default
link policy defines the standard setting for incoming and out-
going connections.
14.1.5 Audio Support
The LMX9838 offers commands to establish and release syn-
chronous connections (SCO) to support Headset or Hands-
free applications. The firmware supports one active link with
all available package types (HV1, HV2, HV3), routing the au-
dio data between the bluetooth link and the advanced audio
interface. In order to provide the analog data interface, an ex-
ternal audio codec is required. The LMX9838 includes a list
of codecs which can be used.
15
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LMX9838
