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參數資料
| 型號： | LMX9820A |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Bluetooth Serial Port Module |
| 中文描述： | 藍牙串行端口模塊 |
| 文件頁數： | 26/44頁 |
| 文件大小： | 579K |
| 代理商： | LMX9820A |
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26
Revision 1.0
L
11.0 Power Reduction
(Continued)
11.0 Power Reduction
The LMX9820A supports several low-power modes to
reduce power in different operating situations. The modular
structure of the LMX9820A allows the firmware to power
down unused modules.
The low-power modes have influence on:
UART transport layer
—enables or disables the inter-
face.
Bluetooth Baseband activity
—firmware disables LLC
and radio, if possible.
11.1 LOW POWER MODES
The following LMX9820A power modes, which depend on
the activity level of the UART transport layer and the radio
activity, are defined:
The activity of the Bluetooth radio mainly depends on appli-
cation requirements and is controlled by standard Blue-
tooth operations such as inquiry/page scanning or an
active link. A remote device establishing or disconnecting a
link may also indirectly change the activity level of the
radio.
The UART transport layer by default is enabled on device
power up. The “Disable Transport Layer” command is used
to disable the transport layer. Therefore, only the host-side
command interface can disable the transport layer.
Enabling the transport layer is controlled by the hardware
wake-up signalling. This can be initiated from either the
host or an LMX9820A input. See also “LMX9820A Soft-
ware Users Guide” for detailed information on timing and
implementation requirements.
11.2 UART TRANSPORT LAYER CONTROL
11.2.1 Hardware Wake-Up Functionality
In some circumstances, the host may switch off the trans-
port layer of the LMX9820A to reduce power consumption.
The host and LMX9820A then may shut down their UART
interfaces.
To simplify the system design, the UART interface is con-
figured for hardware wake-up functionality. For a detailed
timing and command functionality, see the “LMX9820A
Software Users Guide”.
The interface between the host and LMX9820A is shown in
Figure 17.
11.2.2 Disabling the UART Transport Layer
The host can disable the UART transport layer by sending
the “Disable Transport Layer” Command. The LMX9820A
will empty its buffers, send the confirmation event, and dis-
able its UART interface. The UART interface will then be
reconfigured to wake up the LMX9820A on a falling edge of
the CTS pin.
11.2.3 LMX9820A Enabling the UART Interface
Because the transport layer can be disabled in any situa-
tion, the LMX9820A must verify that the transport layer is
enabled before sending data to the host. Possible situa-
tions in which the LMX9820A will need to re-enable the
interface include incoming data or incoming link indicators.
If the UART is not enabled, the LMX9820A must assume
that the host is in a low-power mode and initiate a wake-up
event by asserting RTS and setting HOST_WU to 1. To be
able to respond to the wake-up event, the host must moni-
tor its CTS input (i.e. the LMX9820A RTS output).
As soon as the host activates its RTS output (i.e. the
LMX9820A CTS input), the LMX9820A will first send a con-
firmation event and then start to transmit the events.
11.2.4 Enabling the UART Transport Layer from Host
If the host needs to send data or commands to the
LMX9820A while the UART transport layer is disabled, it
must first assume that the LMX9820A is sleeping and wake
it up by asserting the host RTS output (i.e. the LMX9820A
CTS input).
When the LMX9820A detects the wake-up signal, it
enables the UART and acknowledges the wake-up signal
by asserting its RTS output and HOST_WU signal. Addi-
tionally, the wake-up event will be acknowledged by send-
ing a confirmation event. When the host has received this
“Transport Layer Enabled” event, it knows the LMX9820A
is ready to receive commands.
Table 27. Power Mode Activity
Power
Mode
PM0
PM1
PM2
PM3
PM4
PM5
UART
Bluetooth
Radio
Off
Off
Scanning
Scanning
SPP Link
SPP Link
Reference
Clock
None
12 MHz
12 MHz
12 MHz
12 MHz
12 MHz
Off
On
Off
On
Off
On
Figure 17. UART Null Modem Connections
LMX9820A
Host
RTS#
CTS#
TX
RX
RTS#
CTS#
TX
RX
GPIO
Host_WU
(optional)
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PDF描述 |
|---|---|
| LMX9820ASM | Bluetooth Serial Port Module |
| LMX9820 | Bluetooth Serial Port Module |
| LMX9820SB | Bluetooth Serial Port Module |
| LMX9820SBX | Bluetooth Serial Port Module |
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相關代理商/技術參數 |
參數描述 |
|---|---|
| LMX9820ADEV | 制造商:Texas Instruments 功能描述:KIT DEV FOR LMX9820 |
| LMX9820ADONGLE/NOPB | 制造商:Texas Instruments 功能描述:KIT REF DESIGN FOR LMX9820 |
| LMX9820ASM | 制造商:Texas Instruments 功能描述:BLUETOOTH MODULE, SMD, 9820, FR4129 |
| LMX9820ASM/NOPB | 制造商:Texas Instruments 功能描述:IC MODULE BLUETOOTH 116-LTCC |
| LMX9820ASMX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Bluetooth Serial Port Module |
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