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Hack your old car radio into Bluetooth streaming device




Mazda 3 1.6L 2010

This is my old car, Mazda 3 1.6L 2010 model. This car stereo radio model has no any digital reader like USB or Bluetooth, just CD reader and FM/AM radio function. 



But it has a strange button name "Media" on the right and I can't figure out what this thing for. So, I do a google and find something like below.

AUX input port, car stero, Mazda 3, Sanyo

A media button is for AUX input and it's didn't connect to anything. So, I design to use some Bluetooth module connect to it. Anyway, it's mine and it's old, So I can do anything without feeling pity with it.

Alright, do research

Car stero model nameplate

My car stereo part number is "BCB1 66 ARX" I do research but no luck. There is no any document. But I found something look familiar like my stereo model.


This is an auxiliary pin port diagram of J702 connector, g-pin is right channel input, f-pin is left channel input and e-pin is signal ground. I test by connecting those audio pins to headphone 3.5mm jack an plug it into my phone and connect pin h and b together for enabling auxiliary mode and test by plug it into mobile headphone jack. It's work perfectly!


OVC3860 Bluetooth audio receiver

The OVC3860 is a low power single chip Bluetooth RF transceiver baseband processor for Bluetooth stereo solutions. The OVC3860 is a 2.4GHz RF transceiver, Bluetooth v2 + EDR (Enhanced Data Rate) baseband, can transfer high quality 20bit stereo audio CODEC and a complete on-chip power management unit including switch regulator can support a Lithium Ion, Polymer Batteries and LQ linear regulators.

The OVC3860 has a configurable Bluetooth stack integrated with profiles and applications including A2DP v1.2 AVRCP v1.3, HSP v1.2 and HPF v1.5 integrated with an on-chip SBC decoder, these device is fully compliant with the Bluetooth 2.0+EDR specification that produce a quality Bluetooth Stereo Audio and Voice Communication function.

Features


  • Highly Integrated Bluetooth Audio Solution
  • Low power consumption
  • Supports A2DP and AVRCP high quality stereo audio transmission protocols with the remote control
  • Paired name: BT-Speaker
  • Pair password : 0000
  • Bluetooth Stereo Module
  • Condition: New
  • Chip: ovc3860
  • Bluetooth: version2.0
  • Frequency: 2.402-2.48-Ghz
  • Max transmit power:Class 2 4dBm(at antenna pad)
  • Receive sensitivity: better than -82dBm
  • Range: about 10 meters
  • Data rates Up to 3Mbps(over the air)
  • UART DATA Transfer rate: 115200bps
  • UART: no flow control support
  • Microphone: mono microphone input with bias
  • Profiles: A2DP-sink only
  • AVRCP-Controller only
  • Supply voltage: supply:DC 3.0-3.6V
  • IO:1.7V-3.6V
  • Current consumption: operational-less than 25ma(active)
  • Idle(sleep)
  • External antenna: Connection via S M T pad
  • Dimensions: 30 x 17 x 3.4mm
  • 6 Button to input: boot key, matching key, volume up, volume down, move next, move previous
  • 2 indicator light to indicate different work condition
  • Color : show as pictures
  • PLS NOTE that due to lighting effects, monitor's brightness / contrast settings etc, there could be some slight differences in the color tone of the pictures and the actual item!


I design to use OVC3860 Bluetooth module for this project because it's simple and widely use on the internet. And below is a list of devices.

  • OVC3860
  • Voltage regurator 7805
  • 100u 50v capacitor

Weld it together, 

below is a circuit diagram.



I use universal circuit board and weld it wire by wire.




I put a small ceramic capacitor on high voltage of 7805 ic and hope that can filter some noise out of power supply.



Backside of stereo has a small gap just can put a circuit board. I try to find a power source for this bluetooth module circuit but on auxiliary port is not contain. Sadly, I need to jump power supply from cigarette lighter. Every thing can get worse, so be-careful with this.




Then, I connect bluetooth circuit board with power supply.

Next, I connect an AUX port width data wire and pull it down into backside of ashtray.





Now, connect a cable to Bluetooth board.

We aer ready to test! I turn on a stero push a Media button seem work. Then I turn on blue tooth on my phone it say some bluetooth device avaliabel to connet.

Try connect, It may ask some pass code type 0000.





Finally play some metal song.



Please enjoy! I hope this article can help someone.


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