Well that sucks. (Arduino Stereo Part 2)

Well I received my RN-52, got it all soldered up, and hooked up to my laptop for the initial setup. Once I figured out that I needed to hit enter after entering a command, I got everything set to start streaming music from my phone.

Fantastic. Wait, the sound quality is kind of… wrong. I check the connections to the trrs breakout, everything looks good. Nope. Wait a moment. Flip the connections around. That’s better. Not fantastic though. And now the Bluetooth chip is flaking out if I run at full volume. Perhaps my power supply isn’t running enough current to the chip. No, that’s not it. I eventually gave up on that and tried test calls to see if the audio was OK. Unfortunately not. I have no audio coming through the microphone. Well tits.

So after a couple months with it just sitting there, I noticed that Sparkfun released a new bluetooth chip. The BC127. So I ordered that. When that one arrived, I did the same thing. Soldered everything up, wired it up to the computer, set everything to start streaming music. Fantastic, this one doesn’t crash when I run it at full volume. However, the audio quality isn’t as good as the RN-52. That’s fine, I’ll build an equalizer or something, but at this point, that’s far into the future. And this chip also passes the MP3 metadata through serial. Great, so now I can display the track information on a screen. Fantastic.

When I try to make a call, however, I get the same problem. There is no audio coming through the microphone. This time I did a little more research. I found out that I’m not building the circuit correctly, and I need to put a few more components between the microphone and the chip. Balls. And I can’t for the life of me figure out what I’m missing. I’ve picked up an electret microphone with a built in amplifier, but it’s not working either. This is seriously pissing me off now. Doing a search for electret microphone biasing returns so many different results depending on what you are attempting to do, that I can’t make heads or tails of it.

So I’ve put the project on hold while I learn more circuit building. We’ll see if I can figure this out eventually. If not, I have two chips to build a music box out of.

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About Skullnerd

I could tell you how long I've been on the internet, but I don't remember, or care. I could tell you that I love food, but I don't. I love certain types of food, but not all food. I could tell you that I love music, but I don't. I am a fan of certain artists, and the majority of popular music just pisses me off. I could tell you that I watch a lot of TV... actually, that one is true. Just not reality TV. That shit is boring. My current hobbies are trying to create things out of leather - and screwing them up horribly - and trying to build electronics - and failing miserably. As always, I read fantasy and science fiction. A lot. Anything else you don't need to know.
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7 Responses to Well that sucks. (Arduino Stereo Part 2)

  1. trupthi says:

    Retrieving track metadata via AVRCP with RN-52?how is it done?i need help…

    AVRCP supports transmission of the track metadata (artist, album, track title). Is it possible to receive or retrieve this data with the RN-52 module? If so, it’s not clear from the documentation how that’s done. Are the raw non-audio AVRCP frames sent via the UART?

    • SkullnerdSkullnerdSkullnerd says:

      I didn’t pull the metadata through the RN-52. Unfortunately, that chip doesn’t support it, at least not with the firmware that it came from sparkfun with. I picked up a BC-127, and that chip does do metadata. I have only played with it enough to know that I have no idea of what the hell I’m doing, and am trying to learn more before I go any further.

  2. EE-Mike says:

    hello sir, I found this page on a quick google search of the RN52 and Arduino. I suggest looking at the RN52 development board from Microchip.. Go to their site and look at the schematic (RN51-EK). You’ll see that they use an external audio amplifier to drive external speakers/headphones. The amp is like a $3 IC chip available at many places (the part #) is on the schematic. Also use the capacitors (i would just copy their circuit exactly). Not sure if that will solve your problems but it’s worth a shot!

    • EE-Mike says:

      sorry, RN52-EK is the part number, not 51

    • SkullnerdSkullnerdSkullnerd says:

      Sorry it took me so long to approve your comment, gmail decided that my wordpress emails are spam. Bastards.

      Anyway, I have hooked up both the RN52 and the BC127 according to the schematic for the development boards for both. I’ve never been able to get sound over bluetooth for either. I do know that I’m missing a couple inductors for the BC-127 schematic, but I can’t tell if that is absolutely required.

      Thinking about it though, I don’t know if I tried my amplified electret microphone on the RN52… I might have to try that one of these days.

  3. Martin says:

    Im trying to find a high quality bluetooth module for A2DP and AVRCP. And i need that the sound quality to be very good in the whole range of volume and easy to use. Do you think any of this two modules may be worth? Or maybe you know something else?

    • SkullnerdSkullnerdSkullnerd says:

      The rn-52 doesn’t support AVRCP, so avoid that one as it won’t fit your needs. However, I found that it did have better audio quality than the bc127 at higher volumes. I was never able to get the microphone working on either chip, so I can’t really comment on ease of use. It was hard for me, but maybe if you have more knowledge than I do, it will be easy for you. I only dabble. Someone else would probably be better able to answer your questions.

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