BTM410/411
Bluetooth
®
AT Data Module
47
www.lairdtech.com
Laird Technologies
AT COMMAND SET
REFERENCE
11.
Legacy Issues (BT2.0)
There are some special cases if a legacy device (BT2.0 or earlier, e.g.BISM2) requests a connection
to a BTM device (BT2.1).
General bonding does not work if initiated by the legacy device. Instead, the legacy device must
initiate dedicated bonding first (=pairing, BISM2: “AT+BTW<BdAddr>”). After successful pairing, the
connection can be initiated by the legacy device (BISM2: “ATD<BdAddr>”).
12.
Factory Default UART Baud Rate
BTM devices are capable of operating at a very wide range of baud rates. S Registers 520 and 521
allow the baud rate to be set.
As long as the equation BAUDRATE * 0.004096 produces an integer value, then there will be 0%
error in clocking for that baud rate.
So it is possible to set a baud rate that a PC cannot cope with, and in that circumstance it is virtually
impossible to communicate with it.
To cater for this circumstance, the BTM device will come out of reset using 9600,N,8,1 comms
settings for exactly 750 milliseconds and then revert to the communication parameters as per the S
Registers.
If the host sends the string !<BISM>!<cr> where <cr> is the carriage return character within hat
750ms period, then the module will remain at 9600,N,8,1 and will also configure itself using factory
default
S Register values.
If connected to a PC using Ezurio Terminal, the module can be reset to the factory default baud rate
as follows:
Right click in the Ezurio Terminal window Ú Factory Default Ú Via BREAK/CMD @ 9600
(Tested with version 6.7.2 of Ezurio Terminal)
13.
RI dependent Start-up Mode
The UART_RI line can be configured as an input and on power up its state can be used to force the
device into one of two modes, defining discoverability and connectability state. See description for
S Registers 565 to 569 inclusive for more details.
For example, the feature could allow a device to make an outgoing connection if RI is in one state,
and be ready for an incoming connection in the other.
Содержание BTM410
Страница 1: ...1 Version 3 0 ...