User guide
S535 20 0..41 Link Supervision Timeout. If units go out of range, then a NO CARRIER
message will be sent to the host after the time specified here
S536 0 0..1 When set to 1, a remote device can ‘capture’ the AT parser of this unit by
it sending this module an escape “!!!” sequence. The inter character timing
is set via S Register 12.
If S Register 507 is >= 2, then reading this register will always return 0
and writing 1 will result in ERROR 33.
S537 X X..X This register is no longer available – see 551,552,553 instead
It only exists in firmware version 1.1.12 to 1.1.47
The functionality it controlled is now defined by registers 551,552 and 553
S538 0 0..1 If 1, then when a successful pairing occurs, it is automatically saved in the
trusted device database – if it has room to store it.
S539 0 0..1 When set to 1, in idle mode (S512=1), UART Rx characters are discarded if
DSR is deasserted.
S540 0 0 48..127 Sets the MTU in L2CAP configuration negotiations. The value of 0 is a
special value which is taken to mean that the current value should remain.
S541 6 -50..6 This sets the power level in dBm when inquiring or paging. Reading this
register returns the value stored in non-volatile memory.
S542 6 -50..6 As per S541, however reading this register returns the current power level
as set in the base band. The read can be different from S541because the
actual power is set using a lookup table and the base band rounds down
to the nearest value in the table.
S543 0 0..1 If this is set to 1, then incoming pairing attempts will be accepted (if a pin
code has been pre-entered using AT+BTK) while in the wait phase of auto
connect cycle initiated by the AT+BTR command. In addition to accepting
pairing attempts, if the pairing is successful, then the new device is
automatically set as the peer address for automatic connections (as if an
explicit AT+BTR command was entered).
See S Register 505 and 530 also
S544 1 0..1 Configure the UART for either low latency or maximum throughput. A
setting of 1 gives maximum throughput.
S551 0x3211 0xFFFF This register specifies in each 4 bit nibble, how the outgoing modem status
bits to the remote peer gets its value. Bluetooth allows for RTR, RTC, DV
and IC bits to be exchanged over an RFCOMM connection.
Nibble 0..3 specifies the source for RTC
4..7 specifies the source for RTR
8..11 specifies the source for DV (i.e. DCD)
12..15 specifies the source for IC (i.e. RI)
Each nibble can take the following value:-
0 Always set to 0
1 Always set to 1
2 If DCD (pin 8 on module connector) is output then always 1
If DCD is input then 1 if DCD is asserted otherwise 0
3 If RI (pin 6) is output then always 0
If RI is input then 1 if RI is asserted otherwise 0
4 If DSR (pin 10) is asserted then 1 otherwise 0
In the event that a nibble specifies DSR as the source of its state, be
aware that if, S Register 507 is anything other than 0, a de-assertion of
DSR will cause the Bluetooth connection to be dropped.
If bits 0..3 and 4..7 are set to 0, then some Bluetooth devices will use that
as a signal to stop sending any data back. For example, Nokia 6310 stops
responding.
If this register is changed while in command and connected mode, then on
going back online using the ATO command, a fresh signal will be sent to
the peer to update the bits.
S552 0x0122 0x0FFF This register specifies in each 4 bit nibble, how the DTR, DCD, RI output
pins are controlled when in a Bluetooth connection
Nibble 0..3 specifies the source for DTR
4..7 specifies the source for DCD
8..11 specifies the source for RI
Each nibble can take the following value:-
0 Do NOT touch the I/O
1 Always deassert
2 Always assert
DSH_50003_v1v3 AT Command Reference 13 of 33