Rev-engr bluetooth receiver

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Soundpirate

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Joined 2015
#1
I found this bluetooth reciver discontinued by SE in 2007 or so. It has some musical qualities that makes me want to use it as inspiration for my own bluetooth reciver project or scale it a littlebit and try improve on it, when I have the skills.
I'm not sure what the copyright laws says about that, guess it's nothing extraordinary done inside this one.

I heard there was a lot of smart people in this forum, so I wonder if anyone could help me out with reverse engineering the PCB schematics of this little thing?

-Seems to have a T120 oscilliator, whatever that one is used for(doesnt the bluechip have one inside?)
-8051 IC controller, whatever that one is used for.
-A lot of transistors?
-Wolfson Wm8731ls dac chip
-CSR Bluecore BC358 239Au (I guess this one can be replaced with just about anything that's newer?)


An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.

Probably the pictures could be better..

Thanks in advance🙂
 
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#3
What is the question?

The CSR Bluecore mainly is a SoC with/without DSP-Engine build in. To change/reverse engineer/programm those chips, you'll need the ADK (Audio dev kit) from CSR, which is not available to the public. (NDA stuff)

There exist some software tools on the web you may start with anyway.

https://github.com/lorf/csr-spi-ftdi
Jernej's blog: USB programmer for CSR Bluetooth chips
https://github.com/Frans-Willem/CsrSpiDrivers

You may find some tools in china.

I wouldnt consider investing time in this "old" module but rather get a newer Core revision..

2 pcs 2015 New CSR8645 4.0 Low Power Consumption Bluetooth Stereo Audio Module Supports APTx in Funktion1. Art:F-31882. Bluetooth-Spezifikation:V4.03. Spannung😀c3.3v- 4.2v4. bluetooth-protokoll:HFP v1.6/a2d aus andere elektronische Komponenten auf

Those are the modules i want to use in the future. 🙂
 
#4
Sorry, I ment the Schematic of the PCB(edited the post). But thanks for the additional information!
Yes I'm thinking about switching that chip for a newer one from another manufacturer probably with just some random brand-chip from ebay or some place. Or the ones you recomended. Will this require programming skills?
 
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#6
I've bought both those cards lutkeveld. The first one must have been defective since it popped like crazy so I got my money back. The second one was just poor and noisy. I would not recommend either one. Instead I will recommend this one; Bluetooth V4 0 NFC Aptx Music Receiver Adapter Handsfree Car Aux for iPhone 6 PC | eBay. Its the one with the least noise and it can easily be taken out of it's plastic casing. It runs of a 3.7V lipo and it drives 40 ohms headphones directly too. Apt-x compatible and it works perfect. Only downside is that you have to push play to turn it on every time. I soldered on a bit of wire to the antenna and put a smd cap on the input to make it even quiter.
If anyone have had more success with the boards above pls let me know! I've made a boombox with external switches that could use a good bt card with a good sounding op amp🙂
 
#7
Would it be legal to make my own product and sell it with that CSR8645?Impuls60: Creating something like that is my mission. I'm experienced when it comes to hifi and what to listen for, but I'm stil gathering the knowledge on how to build my own.
 
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#9
Soundpirate said:
Sorry, I ment the Schematic of the PCB(edited the post). But thanks for the additional information!
Yes I'm thinking about switching that chip for a newer one from another manufacturer probably with just some random brand-chip from ebay or some place. Or the ones you recomended. Will this require programming skills?
Click to expand...

I'd guess, you change the whole pcb, not the chip ON the pcb?! 😀

@Impuls60

I recently used small A2DP OVC3860 dongles ($2.50) where i/we changed some stuff in the eeprom. (Until we found a tool named "OVC3860 Rev.E PSKeys Setting Tools" or "RevE_Config_1014" to change almost everything via serial RX/TX)

@Soundpirate

Programming skills are most likely not needed when using BT-modules in a standard setting. But, and thats why i want to use those newer CSR8600 series, if you want to have some nice features or custom code, you'll need an ADK/SDK or the CSR config tools and an SPI-programmer. See attached images.
 

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#15
The filters are done with the Kalimba DSP engine, implementation and configuration should "easy" with some software seen on the screenshots before and a selfmade SPI-programmer.

As i want to use those modules as the base "processor" in small boomboxes, i need to correct the frequency-response a bit more than "linear" to have good "sound presense in the wild".

(Nothing else is done in implementations by Beats, JBL, Harmann etc.)
 
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