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Revision as of 16:04, 21 November 2015 by Chao (talk | contribs) (→‎Dimension)


  • Bluetooth v4.0
  • A2DP v1.2;
  • AVRCP v1.4;
  • HFP v1.6;
  • GAVDP1.2;
  • HSP1.2;
  • Dual MIC Input


  • Model CSR8645
  • 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
  • Standby current <50uA
  • Temperature range -40ºC ~ + 85ºC
  • Wireless transmission range ≤10 meters
  • Transmission power support Class1 / Class2 / Class3 maximum adjustable 9dbm
  • 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
  • Adapter plate size 31x25mm


Pin Definition

Name Number IO IO IO Description

  1. 1 LED2 status indicator (not enabled)
  2. 2 LED1 status lights
  3. 3 LED0 status indicator
  4. 4 AIO0 not enabled
  5. 5 MISO burned into the program interface
  6. 6 CSB program burned into port
  7. 7 CLK burned into the program interface
  8. 8 MOSI burned into the program interface
  9. 9 SPI_EN burned into the program interface enable pin (high enable)
  10. 10 TX serial TX (not enabled)
  11. 11 RX serial RX (not enabled)
  12. 12 VBUS 5V input charging port
  13. 13 RST # low reset
  14. 14 BAT power input (3.3 ~ 4.2V)
  15. 15 POWER_EN module enable control, active-high (delay of 30ms must power)
  16. 16 1.8V 1.8V output
  17. 17 GND Power ground
  18. 18 CHG_EXT External Battery Charge Management
  19. 19 BAT_SENSE External Battery Charge Management
  20. 20 PIO10 not enabled
  21. 21 PIO11 not enabled
  22. 22 PIO12 not enabled
  23. 23 PIO13 not enabled
  24. 24 USB_N USB differential signal negative
  25. 25 USB_P USB differential signal positive
  26. 26 MUTE (PIO9) Mute control (mute, after a period of time is low)
  27. 27 PIO6 not enabled
  28. 28 PP / CALL (PIO7) Play / Pause / receive calls / back / re-pair
  29. 29 PIO8 not enabled
  30. 30 PREV (PIO18) on a
  31. 31 NEXT (PIO19) under a
  32. 32 VOL- (PIO20) Volume down
  33. 33 VOL + (PIO21) Volume up
  34. 34 MIC_BIAS Mike bias voltage
  35. 35 MIC_AN Mike 1 negative end
  36. 36 MIC_AP Mike 1 positive terminal
  37. 37 MIC_BN Mike 2 negative terminal (not enabled)
  38. 38 MIC_BP Mike 2 positive terminal (not enabled)
  39. 39 SPK_R_N1 audio right channel negative differential output terminal
  40. 40 SPK_R_P1 audio right channel positive differential output terminal
  41. 41 SPK_L_N1 Audio left channel differential output negative end
  42. 42 SPK_L_P1 audio left channel positive differential output terminal
  43. 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.

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.

Exbt usb wiring.png

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

EB8000 Differential.jpg
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

Button function.jpg

Status LED

Exbt leds.png

  • Before pairing, the two LEDs will blink in turns
  • After pairing, LED1 off, LED2 blink

Mic Input

  • Note the MIC has polarity

Exbt8645 mic input.png

Battery Charge

  • Better to use a standalone charge module

Exbt battery charge.png

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