User's Guide

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LM074 SPP with GAP Central Application v1.1

If IO-type is keyboard only, the LM074 will expect the passkey from the

user and use it internally for the pairing procedure.

When the IO-type is display only, the LM074 will display the passkey and

the user should use the same passkey on the remote device to complete

the pairing procedure.

When IO-type is Display with yes/no confirmation, the LM074 displays

passkey and expects confirmation from the user whether the passkey for

remote device is the same.

When the IO-type is NO-INOUT i.e. no input no output then it depends on

the peer device whether the pairing will be successful or not. If the IO-

type is No-input-no-output, MITM should be off otherwise the LM074 will

never be able to pair with a remote device.

If the LM074 and remote device has IO-type as No-input-no-output and

MITM as off then devices may pair successfully by “just works” pairing

type.

6.2.1 LM074 has settings DPIN=on, MITM=on, IO-

type=Keyboard-only

i. After the LM074 indicates Pairing as “IND*:PAIR,00126f357215”

and the user accepts the Pairing request with

“AT*PAIR=00126f357215, accept”, the LM074 starts the pairing

procedure.

ii. IO-type as Keyboard only indicates that user can provide Passkey

for pairing using AT commands.

iii. The bluetooth stack will use this passkey for completing the

pairing procedure with the remote device.

iv. During the pairing procedure, the LM074 displays the message

“IND*:PASSK=?”. This indicates that the LM074 requires a

Passkey from the user.

v. The user should respond to this with “at*passkey=1234”. i.e. the

passkey for the remote device is 1234. It can be any integer in

range of 32bit value.

vi. After completing the pairing procedure, the LM074 indicates the

status of pairing to the user e.g. “IND*:PAIR=OK,00126f357215”

or “IND*:PAIR=FAIL,00126f357215” .

6.2.2 LM074 has settings DPIN=on, MITM=on, IO-

type=display only

i. After the LM074 shows indication of Pairing

“IND*:PAIR,00126f357215” and user accepts the Pairing request