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Electronics => Beginners => Topic started by: Lee_horner93 on June 13, 2018, 06:39:37 am

Title: Bluetooth speaker module (spk md blk-b)
Post by: Lee_horner93 on June 13, 2018, 06:39:37 am

Hi folks! I've been working on a a small Bluetooth project, creating a set of Bluetooth headphones, using the Bluetooth speaker module spk md blk-b that I purchased a few weeks ago from  somewhere in China. Unfortunately I can't find any proper wiring diagrams or schematics for this specific chip, I will attach a few pictures. The problem is I can't seem to power the chip up no mater what I try, and I have tried with two separate modules.
I have seen diagrams of similar modules that feature a multi function button (mfb) that requires a long press (3sec) from the power supply to power it up. If anybody has any information on the chip that I have or know off any other methods to try and power it up that would be great!

Title: Re: Bluetooth speaker module (spk md blk-b)
Post by: Buriedcode on June 13, 2018, 12:18:23 pm

Depending on which diagram you provided is your module, you need to pull the "Vreg" or "MFB" line high - to Vbatt via a 10k resistor will do.  MFB = multifunction button and is usually the "pairing/power on/off" button on bluetooth audio devices.  It is also sometimes referred to as Vreg, even though it is an input.  It is essentially what powers up/down the internal 1.8V regulator which powered the chip.

I assume you mean this module: https://www.elecfreaks.com/wiki/index.php?title=BLK-MD-SPK-B (https://www.elecfreaks.com/wiki/index.php?title=BLK-MD-SPK-B)

Title: Re: Bluetooth speaker module (spk md blk-b)
Post by: Lee_horner93 on June 13, 2018, 01:10:26 pm

Thanks for the response! Apologies the top image is the board I have, with the charging pins across the bottom. I will try this later. You wouldnt happen to know if the 1.8v circuit earths on the same pins as the 3.3v circuit?
(https://uploads.tapatalk-cdn.com/20180613/d46af98d4ed4b216d98d9a3e366c44f4.jpg)(https://uploads.tapatalk-cdn.com/20180613/026a2c453c0ab1b6a7470a76efa0d25f.jpg)

Sent from my SM-G935F using Tapatalk

Title: Re: Bluetooth speaker module (spk md blk-b)
Post by: Buriedcode on June 13, 2018, 01:20:15 pm

Yes, all the grounds should be connected.  The 1.8V comes frm the module (on-board voltage regulator) but the 3.3V is supplied externally.  It is designed to run from a lithium polymer battery so 3.3-4.2V on Vbatt.  So for your module, Vbat is 3.3V in, and "Vreg" should be connected to Vbat by a 10k resistor.

Title: Re: Bluetooth speaker module (spk md blk-b)
Post by: Lee_horner93 on June 13, 2018, 05:33:23 pm

Just tried tried pulling the Vreg pin high and it works perfectly! Thanks very much!

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Title: Re: Bluetooth speaker module (spk md blk-b)
Post by: suraj on August 28, 2018, 06:23:02 am

need a help to design a low cost bluetooth speaker. It will be very helpful if you provide me a refrence circuit daigram