I have used these modules pretty extensively. The original ones had all th= e problems Harrison listed. The worst problems were the 2GB limit on the CD card, and having to convert the audio files to 4D's proprietary format. Happily, a few months ago they introduced the SOMO-II which solves both of these problems. You can now use virtually any size (capacity) of micro-CD, and it will play mp3 files directly. Sound quality is subjectively pretty good! (I've never made any actual measurements of it.) Only problem is it is pretty pricey, ie north of $20 in small quantities. However, it is pretty easy to interface and does work well for us. Here's a link: http://www.4dsystems.com.au/product/SOMO_II/ Foster =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Harrison Cooper Sent: Friday, December 12, 2014 8:55 AM To: Microcontroller discussion list - Public. Subject: RE: [EE] Sound Module Opinions? There are a lot of the small microSD based, and SD based using the chip tha= t Sparkfun uses, on Ebay. I have a box of them actually, from a project I did last summer that was a trigger-able audio device, built in trigger delays, audio amp, relays, etc and run from a PIC of course. The code was pretty simple but several issues. I have a pile of blank boards too if anyone is interested. And a box of the microSD players too. Contact me offlist if your interested in the details. 1. As Mike said, limited to 1 or 2 Gb cards and those are being thrown away more than sold on ebay. 2. Resets are needed. I basically sent a reset each time I would address, but even then the audio would not always trigger...sometimes there would be delays. 3. The files have to be converted from wav or MP3 to the .ad4 format. I would sometimes have to play with audio levels, depending on the source to get a decent converted sounding file. 4. Audio quality. Its...acceptable. Again if the source is crap...how can you expect the converted file to be ok. For my application, it was fine. 5. Heat. Mike did the design correctly....in the boards available on ebay....if you run them a lot..continious, the chip overheats and uses the microSD as its heatsink. NAND doesn't like getting really hot...and becaus= e the chip was on the other side of the clip it would get really hot and then fail. I tried turning down the output level for its internal amp because I was using another amp outside it but it didn't seem to help. I'm in the process of changing the design, due to some user controls and mounting issues not so much because of the audio player (I was moving to th= e SD version http://www.ebay.com/itm/WTV020-SD-20SS-SD-card-voice-module-MP3-Voice-modul= e -U-disk-audio-player-/131288629263?pt=3DLH_DefaultDomain_0&hash=3Ditem1e916= 9800f ) because of the heat issue and the cost of this is $7 vs $20 from sparkfun.) Oh for the audio amp....I used the PAM8403, pretty good chip actually. I n= o longer have access to an Audio Precision to look at the real frequency response but from a subjective perspective, its pretty good and a easier solution than a TI based class D amp. So I'm quite interested in a sub $10 audio solution, I have no problem laying it down on the board either. I once did a player using the MP3 decoder from VLSI (?) that was popular a few years ago but again, its not a low cost chip. -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of Mike Hord Sent: Thursday, December 11, 2014 8:29 PM To: Microcontroller discussion list - Public. Subject: Re: [EE] Sound Module Opinions? That 4d one uses the same chip ours does. It has the same problems. To elaborate on the problems: audio quality isn't great, the part seems to go off the rails in its internal state machine, requiring a reset. It's har= d to ensure that the audio file will work; sometimes it just...doesn't, for n= o apparent reason. The part only supports 2GB and smaller cards, which are getting scarce. That's not to say it's completely useless; obviously plenty of people get i= t to work or we wouldn't sell it. It's just a little hairy sometimes. Someday, when I've solved all the other mysteries in the building, I'll mak= e one that doesn't have these problems. Mike On Dec 11, 2014 6:05 PM, "Josh Koffman" wrote: > On Thu, Dec 11, 2014 at 7:48 PM, David Duffy (AVD)=20 > wrote: > > The ones from Tenda are not too bad to use. You can stop and=20 > > restart an > > mp3 midway. > > David... > > Interesting. I found a source in Canada: > > http://www.robotshop.com/ca/en/4d-systems-embedded-audio-sound-module. > html > > Though they are out of stock at the moment. One of the reviews I read=20 > said that this was extremely quiet when connected directly to a=20 > speaker. Does that match your experiences? > > Regarding stopping and starting, I'm hoping to stop and re-start from=20 > the top. Have you tried this? > > Thanks! > > Josh > -- > A common mistake that people make when trying to design something=20 > completely foolproof is to underestimate the ingenuity of complete=20 > fools. > -Douglas Adams > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive=20 > View/change your membership options at=20 > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/chang= e your membership options at http://mailman.mit.edu/mailman/listinfo/piclist ________________________________ PLEASE NOTE: The information contained in this electronic mail message is intended only for the use of the designated recipient(s) named above. If th= e reader of this message is not the intended recipient, you are hereby notified that you have received this message in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. 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