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DSH_BT024-00200_1v4 © Ezurio Ltd 2006
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9.4
Audio Cable (voice)
With a pair of these modules it is possible to replace a mono audio cable with two way traffic. That is, a setup
where a microphone is connected to a speaker at the remote end and vice versa. So this mode effectively
replaces two audio cables.
Assuming the
Bluetooth
address of the master to be <bdaddr_m> and that of the slave to be <bdaddr_s>, the
master module is configured by sending it the following AT commands:
AT&F*
ATS512=1
ATS504=1
ATS530=2000
ATS532=7
AT&W
AT+BTR<bdaddr_s>
And the slave is configured by:
AT&F*
ATS512=4
ATS0=-1
AT&W
AT+BTM<bdaddr_m>
9.5
Modem Control and Status Signals
A serial port has DTR, DSR, RTS, CTS, DCD and RI control lines. RTS and CTS are locally controlled to prevent
local buffer overflow.
The status of DTR, DRS, DCD and RI can be exchanged with the remote peer device. If for example, the
DTR/DSR lines are to be exchanged between the two peers to simulate the performance of a physical cable, then
it is possible to do so. Refer to the description for S Registers 551, 552 and 553 for more details.
Some serial implementations link CTS and RTS to remove the need for handshaking. Ezurio do not recommend
linking CTS and RTS other than for testing and prototyping. If these pins are linked and the host sends data at
the point that the
Bluetooth
Serial Module deasserts its RTS signal, then there is a significant risk that internal
receive buffers will overflow which could lead to an internal processor crash. This will lead to a drop in connection
and may require a power cycle to reset the module.
Ezurio recommend that the correct CTS/RTS handshaking protocol be adhered to for proper operation.
9.6
Oscillator Output
The output from the high performance crystal oscillator (+ 10ppm) can be divided and output on one of the
selected PIO lines, removing the need for a crystal on the customer’s main pcb. The frequencies available are:
•
8 MHz
•
16 MHz
•
24 MHz
•
48 MHz
For more implementation details, please contact Ezurio’s FAE team.