BTM410/411
Bluetooth
®
AT Data Module
22
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Laird Technologies
AT COMMAND SET
REFERENCE
2.
IO-Capability (S321)
S-Register 321 defines the IO-capability of the device. The setting is used for IO-capability
negotiations prior to SSP in order to identify whether the IO-capabilities of both devices are
sufficient for MITM protection (if required). Table 3-11 lists possible values.
Table 3-11: IO capabilities
S321 IO-Capability
Comment
0
Display only
The device has the capability to display or communicate a 6
digit decimal number.
1
Display yes no
The device has the capability to display or communicate a 6
digit decimal number and at least two buttons that can be
easily mapped to ‘yes’ and ’no’ or a mechanism whereby the
user can indicate either ‘yes’ or ‘no’ (e.g. pressing a button
within a certain time limit)
2
Keyboard only
The device has a numeric keyboard that can input numbers ‘0’
through ‘9’ and a confirmation. The device has also at least
two buttons that can be easily mapped to ‘yes’ and ’no’ or a
mechanism whereby the user can indicate either ‘yes’ or ‘no’
(e.g. pressing a button within a certain time limit)
3
No input no output
The device does not have the ability to indicate ‘yes’ or ‘no’,
and the device does not have the ability to display or
communicate a 6 digit decimal number.
4
Reject IO-Cap requests
IO-capability requests prior to SSP are rejected.
3.
Force Man-In-The-Middle Protection (MITM, S322)
Protection against MITM-attacks can be enabled by S332. This S-Register only applies if the security
level (S320) is less than 3. In case of security level (S320) = 3, MITM protection is always enabled
and this S 322 is ignored.
A new value written to S322 applies immediately. No power cycle is required.
A link key created with MITM protection is named “authenticated link key”.
A link key created without MITM protection is named “unauthenticated link key”.
4.
Disable Legacy Pairing (S323)
If the remote device is a legacy device (BT2.0 or earlier), legacy pairing with usage of PIN codes will
be initiated. Legacy Pairing can be disabled by S-Register 323 = 1. Then pairing with legacy devices
will always fail.
5.
SSP Timeout (S324)
The SSP timeout [s] is defined by S-Register 324. The timeout must be at least 60s to meet the BT
specification requirements [1]. This time is required to be sufficient for the user to compare or read
and input a 6 digit number. A time of 90 seconds is recommended which is the default value.
Содержание BTM410
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