Introduction, and question about hard-to-find components.

Question

Hello, I'm Jon, based in mid-Wales. Interested in making products for people with visual impairments.

Had a great training course last weekend at BCA in Birmingham with Arduino-evangelist Garry Bulmer running an excellent one-day course.

I was so enthused I bought an Uno kit on the spot and was chuffed when, two evenings later with nothing more than the Uno, 1 switch, 1 resistor, 1 speaker and 3 bits of wire, I had the Uno saying "ready" and then "button up" or "button down" depending on the state.

Having never done MCU fiddling before, and my programming knowledge limited to PHP, I was quite pleased. Next project is to use a cheap Freeduino to see if I can make a light activated chicken-run door opener for under £20.

I've got a LOT to learn, and this place is such a massive resource it's a bit mind-boggling. Spent about 5 hours here today, just bookmarking stuff, noting what lives where.

I hope no-one minds if this next question is a bit of a newbie-FAQ, but here goes anyway!

I'm on the lookout for an embedded audio (mp3, also preferably m4a/mp4, ogg and maybe wma) decoder chip which allows fast forward/rewind within a track.

Also, when finding parts, is there a formula for different versions and names? For example, I found a CSC4863FN chip inside one mp3 player, which appeared to not exist, but then I found a document linking it to LM4863, which seemed to be identical, and there were hundreds available everywhere.

So anyway, here are a couple of multi-function chips I found in different all-in-one mp3 player devices: GPDS206A which I can find nothing about, anywhere (not even datasheets) and the ALCOR AU3130 (superseded by AU3150). I found the latter, but the manufacturer seems to want either orders of 10,000 or $255 for a dev kit. Didn't want to be bothering Farnell with that kind of newbie question...

But even if I could find those chips, they all seem to suffer the same problem as every other unit, and also every Arduino "mp3 shield" type project I've seen (so far!), which is that none of them seem to allow fast forward/rewind within a track.

Ideally, it would be some MCU-controlled all-in-one USB reader and mp3 player -> line/headphone out. In fact, there's a module that does just that, the Vinculum Vmusic 2, but it's between £37 and £40!! And even that can't do FF/RW.

So, how do these companies make pocket/tabletop mp3 players for £5/£10 complete with speakers, power, battery, FM radio etc for that price AND include a chip? I realise volume production in China is key here, but surely there's something cheaper than the Vmusic for my project, preferably Arduino compatible?

Anyway, I'll stop waffling on there. Go gentle on me, it's my first time!

Former Member · Answer

A selection of CODECs can be found at http://uk.farnell.com/codecs

CODECs: 5 products found MP3

As far as LM4863 (Audio amp BTW) versus CSC4863FN goes, if a chip is popular and profitable many companies will make their own version of it. Copyright issues, Patent issues and revese-engineering are always a concern of course. LM used to mean Linear Monolthic, but generally it is now a manufacturer prefix (frequently but not always from National Semicounductor now part of TI) Suffixes are frequently package type and other parameters. Always check the data sheets for definitions.

The application below is programmable logic based, but I think Fast forward has more to do with processing than decode.

http://www.xilinx.com/support/documentation/application_notes/xapp328.pdf

As far as the economics of high volume production goes, when a vendor is able to amortize the cost of tooling over the highest volume possible, tooling's impact on the per part price goes way down. Look and any part with a price break at 10, 100, and 1000 then just keep going by orders of magnitude and the per part cost starts to approach the cost of raw materials.