EXBT
Features
- Bluetooth v4.0
- A2DP v1.2；
- AVRCP v1.4；
- HFP v1.6；
- Single MIC input
for EX8645:
- GAVDP1.2；
- HSP1.2；
- Dual MIC input
Performance
- Model CSR8645/8635
- Bluetooth specification Bluetooth V4.0
- Modulation GFSK, π / 4 DQPSK, 8DPSK
- Supply voltage DC3.3-4.2V, ≤3.0V automatic shutdown, ≤3.2V alarm
- Bluetooth protocol HFPV1.6, A2DPV1.2, AVRCPV1.4, HSPV1.2
- Working current ≤30mA for 8645, ≤13mA for 8635
- Standby current <50uA or 8645, <2mA for 8635
- Temperature range -40ºC ~ + 85ºC
- Wireless transmission range ≤10 meters
- Transmission power support Class1 / Class2 / Class3 maximum adjustable 9dbm for 8645, and 8dbm for 8635
- Sensitivity -80dBm <0.1% BER
- Frequency Range 2.4GHz ~ 2.480GHz
- External Interface USB (USB sound card)
- Audio performance supports ACC, MP3, SBC, APT-X decoder
- Audio SNR ≥75dB
- Distortion ≤0.1%
- Module size 26.2x13.5x0.8mm for 8645 and 24.5x14.1x2.0mm for 8635
- Adapter plate size 31x25mm for 8645 and 29x24mm for 8635
Dimension
8645 Board
8645 Convert Board
Pin Definition
Name Number IO IO IO Description
- 1 LED2 status indicator (not enabled)
- 2 LED1 status lights
- 3 LED0 status indicator
- 4 AIO0 not enabled
- 5 MISO burned into the program interface
- 6 CSB program burned into port
- 7 CLK burned into the program interface
- 8 MOSI burned into the program interface
- 9 SPI_EN burned into the program interface enable pin (high enable)
- 10 TX serial TX (not enabled)
- 11 RX serial RX (not enabled)
- 12 VBUS 5V input charging port
- 13 RST # low reset
- 14 BAT power input (3.3 ~ 4.2V)
- 15 POWER_EN module enable control, active-high (delay of 30ms must power)
- 16 1.8V 1.8V output
- 17 GND Power ground
- 18 CHG_EXT External Battery Charge Management
- 19 BAT_SENSE External Battery Charge Management
- 20 PIO10 not enabled
- 21 PIO11 not enabled
- 22 PIO12 not enabled
- 23 PIO13 not enabled
- 24 USB_N USB differential signal negative
- 25 USB_P USB differential signal positive
- 26 MUTE (PIO9) Mute control (mute, after a period of time is low)
- 27 PIO6 not enabled
- 28 PP / CALL (PIO7) Play / Pause / receive calls / back / re-pair
- 29 PIO8 not enabled
- 30 PREV (PIO18) on a
- 31 NEXT (PIO19) under a
- 32 VOL- (PIO20) Volume down
- 33 VOL + (PIO21) Volume up
- 34 MIC_BIAS Mike bias voltage
- 35 MIC_AN Mike 1 negative end
- 36 MIC_AP Mike 1 positive terminal
- 37 MIC_BN Mike 2 negative terminal (not enabled)
- 38 MIC_BP Mike 2 positive terminal (not enabled)
- 39 SPK_R_N1 audio right channel negative differential output terminal
- 40 SPK_R_P1 audio right channel positive differential output terminal
- 41 SPK_L_N1 Audio left channel differential output negative end
- 42 SPK_L_P1 audio left channel positive differential output terminal
- 43 RFOUT antenna (default built-in antenna, external disconnect)
Design Circuits
Bluetooth power up on boot
- VCC (3.3 ~ 4.2V), when using an external power supply: 3.3V (ASM1117) power supply. When using lithium batteries: lithium guarantee voltage between 3.3V ~ 4.2V;
- Recommendations Bluetooth module supply terminal in parallel with the capacitor 104 470uf suppress interference;
- 1V8 output voltage.
- As shown above connection, this time it did not work after the power module, because the module "PWER_E" is not enabled, as shown below on the electric start mode.
convert board simple power up
stable power up in application
Connect as USB card
- Simply access the module after Figure 4 and connected to the computer to be recognized as a USB sound card, driver-free;
- Recommendations USB cable not too long;
- The default version of the firmware with USB sound card function;
- USB sound card and Bluetooth functions can not work simultaneously.
Headset Connection
- Output to 3.5mm headphones or 3.5mm input soundbox
- Only tested for headset function, not LRG audio amplification
- SPK_LN and SPK_RN connect either one, not both
Differential four wires
About circuits:
- Auto enable on CTRL pin
- when 5V VCC, speaker can use 4ohm|3W
- C21, C22 keep close to HT6872;
- Module control chip mute welding R22, no welding R21. No control, welding R21, no welding R22.
- Recommendations for soldering of R21, no welding R22, reason is when play a song and in the silent phase, a module considered to be muted, it will shut off HT6872 and cause discontinuities stopped play.
Button Function
Status LED
- Before pairing, the two LEDs will blink in turns
- After pairing, LED1 off, LED2 blink
Mic Input
- Note the MIC has polarity
Battery Charge
- Better to use a standalone charge module
Design note
- If the next antenna modules have batteries, metal, LCD screen, speaker, and requires a minimum distance from the antenna 3cm, it is recommended to use an external antenna.
- Layout supply line is recommended when using the star alignment and ensure that the performance of the Bluetooth module power supply line is better. There BT, with op amp, amplifier, MCU, etc. separated, and the lower side of BT shall have no other interference, we recommend Bluetooth module on the bottom corner.
- It recommended that the module antenna portion of the float in the floor, but can not go around the antenna control cable, power cable, audio cable, MIC and other interference lines, if the module to be placed in the middle, to be slotted in around the antenna, it is recommended to use an external antenna .
- If there is row seat near the antenna module, housing a metal iron net impact on the signal, it is recommended to use an external antenna to solve the distance problem.
- When an external amplifier module to be connected to the differential input of the amplifier, if you do not take a differential input amplifier, you must be connected to a balance of the two differential amplifier level, otherwise there will be "pops" the impact of sound.
Reference Design Circuit
USB card
PAM8610 Amp Board
HT6872 Amp Board
HT8696 Amp Board
Differential and headset
Differential and headset
