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8.0 Functional Description
(Continued)
8.6.4 Configuring the LMX9830 through transport layer
As described in Section 8.5 "System Power Up" on page 15,
the LMX9830 will check during startup the Options Regis-
ters if an external PROM is available. If the information on
the PROM are incomplete or no PROM is installed the
LMX9830 will boot into the “initialization Mode”.
The mode is confirmed by the “Await Initialization” Event.
The following information are needed to enter Bluetooth
Mode:
■
Bluetooth Device Address (BD_Addr)
■
External clock source (only if 10 - 20 MHz has been
selected)
■
UART Baudrate (only if Auto baudrate detection has
been selected)
In general the following procedure will initialize the
LMX9830:
1. Wait for “Await initialization” Event
- Event will only appear if transport layer speed is set or
after successful baudrate detection.
2. Send “Set Clock and Baudrate” Command only if the
clock speed is not known through hardware configura-
tion
(i.e only if OP3 OP4 OP5 = 0 1 0)
.
3. Send “Write BD_Addr” to Configure Local Bluetooth De-
vice Address.
4. Send “Enter Bluetooth Mode”
- LMX9830 will use configured clock and UART speed
and start the command interface.
NOTE: In case no EEPROM is used, BDAddr, clock source
and Baudrate are only valid until the next power-cycle or
hardware reset.
8.6.5 Auto Baud Rate Detection
The LMX9830 supports an Automatic Baudrate Detection in
case the external clock is different to 12, 13MHz or the
range 10-20 MHz or the baudrate is different to 9.6 kbps,
115.2 or 921.6kbit/s.
The baudrate detection is based on the measurement of a
single character. The following issues need to be consid-
ered:
■
The flow control pin CTS must be low or else the host is
in flow stop.
■
The Auto Baudrate Detector measures the length of the
0x01 character from the positive edge of bit 0 to the
positive edge of stop bit.
■
Therefore the very first received character must always
be a
0x01
.
■
The host can restrict itself to send only a 0x01 character
or also can send a command.
■
The host must flush the TX buffer within 50-100 millisec-
onds depend on clock frequency on the host controller.
■
After 50-100 milliseconds the UART is about to be initial-
ized and short after the host should receive a “Await
Initialization” Event or an “Command Status” Event.
Table 18. Fixed Frequencies
Osc Freq.
(MHz)
BBCLK
(MHz)
PLL
(48 MHz)
OP3
1
OP4
2
OP5
3
Function
12
12
OFF
0
0
0
UART speed read from NVS
10-20
4
10-20
1
ON
0
1
0
Clock and UART baudrate detection
13
13
OFF
1
0
0
UART speed read from NVS
13
13
OFF
1
0
1
UART speed 9.6 kbps
13
13
OFF
1
1
0
UART speed 115.2 kbps
13
13
OFF
1
1
1
UART speed 921.6 kbps
1.
2.
3.
4.
If OP3 is 1, must use 1k ohm pull up.
If OP4 is 1, must use 1k ohm pull up.
If OP5 is 1, must use 1k ohm pull up.
Supported frequencies see Table 22 on page 24
Figure 11. Auto baudrate detection timing diagram
CTS
RX
0x01
0x00
50 - 100ms delay