LM Technologies LM740 User manual

Stereo headset mode
User’s Guide
Rev 1.0
1. Overview
The LM740 is CSR ®BlueCore 5®MM based Bluetooth module and is suitable for A2DP, SPP, DUN, OPP, FTP,
PBAP and HID applications. It also allows to implement advanced functions such as noise cancellation and
multi-media streaming. The LM740 module board is de signed for using with the LM556 Bluetooth module
Evaluation Kit. This user’s guide will introduce the settings of LM556 with LM740 module board to implement
wireless stereo headset application.
2. The Settings
LM740 Stereo Loud speakers
Device name：LM740 RX-HIC
Profiles：A2DP-Sink, AVRCP, HFP/HSP
Pin code：0000
Image file: LM740-RX-HIC.zip
Description: These settings enable the LM556 with LM740 module board to receive A2DP streaming from
music audio source as well as answering phone call with HFP/HSP. That is, to implement the wireless stereo
headset application.
When receiving or making a call, the music playback will be automatically paused. The music playback can be
resumes when the call is ended.
Each time the LM740 - RX - HIC is switched on, it will intend to connect to the Bluetooth device that the last it had
connected with.
The LM740 -RX-HIC has battery low detection and protection. When battery low occurred, it will worn by
flashing red LED. If the battery is exhausted, the firmware will switch off the system to protect the Li-ion battery.
LM740
Running
A2DP, AVRCP
profiles
A2DP Streaming
LM556 Development Board

LM556- Blue LED (LED1) & Red LED (LED0) Indicators
Operating State Blue LED (LED1) & Red LED (LED0) controlled by LM740
Standby The system is standby but not connected to any Bluetooth device yet.
Blue LED: (repeat cycles) 2 seconds on, 1 second off.
Pairing mode Flashing Blue and red LEDs alternatively.
Connecting state Try to connect with paired Bluetooth device.
Blue LED is flashing rapidly (in blue).
Both A2DP and HFP are
connected Flashing Blue LED twice by every 2 sec.
Only A2DP is connected Flashing Blue LED once by every 2 sec.
Only HFP is connected Flashing Blue LED once by every 4 sec.
Battery Low Flashing Red LED once by every 5 sec
Charging the battery Red LED steady on
LM556 Jumper Settings
snoitpircseD.oNrepmuJ
J1 Ø3.5mm phone jack for audio output
JP3, JP4
Battery charger settings. Please refer to the “ LM556 Evaluation Kit General Guide” for
details.
Warning: To use the internal charger of LM740, the Li-ion re-chargeable battery shall
be installed permanently.
JP6 Short circuit to pin1 & pin2.
Set the voltage level of SPI interface to LM740 module board.
JP14, JP17 Short circuit to pin2 & pin3 to each of these jumpers.
These will wire the MIC1 to the audio input of LM740.

J15Short circuit.
Select 3.3V for system power
JP20, JP22, JP25,
JP26
Short circuit to pin1 & pin2 to each of these jumpers.
These will wire the audio outputs (L & R channels) of LM740 to headphone amplifier.
and then output to J1 phone jack.
JP24 Short circuit to pin2 & pin3.
Select 3.3V for power supply to LM740 module board
JP27 Short circuit to pin2 & pin3.
Select active low Reset for LM740 module board
JP28 Short circuit to pin2 & pin3.
Select 3.3V for the signal level of PIOs of LM740 module board
JP29 Short circuit.
Seelect 3.3V for headphone power supply.
JP30 Short circuit to pin2 & pin3.
Enable the self sustain powering scheme
JP31 Short circuit
Enable 3.3V power supply to the driver ICs of printer port (SPI) and serial port.
On/Off/Pairing Control 1. Pressed and held for more than 2 seconds can turn on/off the module board.
2. Short pressed will set the module board to Pairing mode.
MFB (PIO6) This is multi-function button for A2DP and HFP modes. Please refer to firmware guide of
LM740 RX-HIC version.
Rewind (PIO7) Rewind the music playback (A2DP) of the audio source by AVRCP.
Fast Forward (PIO8) Fast Forward the music playback (A2DP) of the audio source by AVRCP.
Volume Up (PIO11) Turn volume up of the audio source.
Volume Down (PIO12) Turn volume down of the audio source.
System Power Switch Disengage ‘System Power Switch’ that allows the operation of ‘On/Off/Pairing Control’
button

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UART_TX
PIO2 PIO1
SPKR_A_N
PIO0
PIO9
SPKR_R_P
AIO1
USB_DP
SPKR_A_P
PIO10
MIC_A_P
MIC_BIAS
PIO_POWER
MIC_A_N
USB_DN
PIO3
VDD_CHG
VREG_EN
PIO12
PIO_POWER
AIO0
UART_RX
MIC_B_P
SPKR_R_N
MIC_B_N
PIO11
LED0
LED1
UART_CTS
UART_RTS
PIO8 PIO7 PIO4 PIO6 PIO5 RESET PCM_IN PCM_CLK
PCM_SYNC
MOSI PCM_OUT CSB MISO CLK
PIO_POWER
PCM_SYNC
USB_DN
SPKR_A_N
SPKR_B_N
MIC_BIAS
PCM_IN
AIO1
SPI_CLK
PIO5
SPKR_B_P
PIO11
SPI_MOSI
SPI_MISO
MIC_A_P
PIO8
PIO7
VREG_EN
PIO_POWER
LED0
VDD_CHG
USB_DP
PIO9
UART_CTS
LED1
MIC_A_N
MIC_B_N
RESET
AIO0
UART_RTS
SPKR_A_P
PIO12
PCM_CLK
SPI_CSB
PCM_OUT
UART_TX
UART_RX
MIC_B_P
PIO6
PIO10
PIO0
PIO1
PIO2
PIO3
PIO4
DGND
VBAT
1V8
DGND
AGND
DGND
DGNDDGND
DGND
DGND
DGND
DGND
DGND
DGND
AGND
VBAT
DGND
1V8
AGND
VCC
AGND
AGNDDGND
C24
1pF
C25
NC
C46
0.1uF
L10
1.5nH
C45
10uF/0805
C23
NC
L9
22uH
C22
10uF/0805
U2
Module Board
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
22 23 24 25 26 27 28 29 30 31 32 33 34
35
36
37
38
39
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
19
20
1
21
40
VREG_ENA
DGND
DGND
DGND
AIO0
AIO1
PIO0
PIO1
PIO2
PIO3
USB_D-
USB_D+
PIO9
PIO10
UART_RXD
UART_TXD
VDD_IO
DGND RESET UART_NRTS UART_NCTS PIO8 PIO7 PIO6 PIO5 PIO4 PCM_IN PCM_OUT PCM_SYNC PCM_CLK
DGND
SPI_NCSB
SPI_CLK
SPI_MISO
SPI_MOSI
LED1(PIO)
VDD_BAT
VDD_CHG
AGND
MIC_BIAS
AUDIO_IN_P_RIGHT
AUDIO_IN_N_RIGHT
AGND
AUDIO_IN_P_LEFT
AUDIO_IN_N_LEFT
AUDIO_OUT_N_RIGHT
AUDIO_OUT_P_RIGHT
AGND
AUDIO_OUT_N_LEFT
AUDIO_OUT_P_LEFT
PIO11
PIO12
VCC
1V8
LED0(PIO)
R57
0R
TP6
1
U22
LM740
1 10 13 12 14 6 4 3 11 5
20
33
8
54
36
27
28 29
26
23
22
21
25
24
17
16
19
18
9
15
31 34 32
46
42 30 41 38 39 37
43
40 35 7
2
47
45
44
48
49
50
53
52
51
55
AGND
AUX_DAC
PIO3 PIO1 PIO2
PIO_POWER
SPKR_A_P
SPKR_B_N
PIO0
SPKR_A_N
UART_RX
PIO6
RF_IO
MIC_A_P
PCM_IN
PIO12
GND PIO8
PIO11
UART_CTS
UART_RTS
UART_TX
PIO9
PIO10
USB_DN
AIO0
VDD_USB
USB_DP
GND
AIO1
PIO4 RESETB PIO5
1V8
SPI_MISO PIO7 SPI_CLK PCM_OUT SPI_MOSI PCM_SYNC
GND
SPI_CS#
DNGKLC_MCP
SPKR_B_P
LX
LED0
LED1
VDD_CHG
VBAT
POWER_ON
MIC_B_N
MIC_B_P
MIC_BIAS
MIC_A_N
R63
NC/0603
R53
10K
ANT9
Antenna
1
LM Technologies
MS/SP LM556 rev1