Using portable RAM Card as digital source

[eric9099]

Would like to know if it is possible to make read sound files from a portable RAM card (stand alone, without a computer) and output as digital signal for DAC.

[Christer]

I assume you mean flash cards, like SD cards.

I haven't really looked at any details of it, but I think you could use the Vinculum chips from FTDI together with an ordinary USB card reader. The actually sell small boxes based om this chip with built-in card reader with either USB or headphone jack as output, so maybe the easiest could be to try modifying one of those?
http://www.vinculum.com/
(Check downloads for free drivers for various things).

And then there a zillions of other ways you could do it to, I suppose,

[audiosteve]

Find an iRiver H100 series player. It has an optical digital out. It's not solid state but I think it is what you are looking for in terms of functionality. They are discontinued. I found mine as a refurbished unit on E-bay. Playing WAV or FLAC files to a good external DAC yields excellent sound.

[audiosteve]

I just checked out the Vinculum website. They have the VMUSIC 1 and VMUSIC2 modules. The schematic available for the VMUSIC 1 shows it using a VLSI VS1003 MP3 decoder chip. This part has the DAC internbal and the digital lines needed to create a SPDI/F or other digital I/F are not present. In addition, the specs on the integrated DAC are pretty crappy.

[Christer]

I didn't mean to use the Vinculum chip for much else than reading the flash card and converting the data to some format suitable for the DAC. My understanding was that Eric already has a DAC and just want to be able to use flash cards as a source. Of courser there are many other chips that could do that too, and maybe there are much better choices.

[eric9099]

Yes, I have a DAC and would like to see if it is possible to make a SD card reader and output SPDI/F signal for my DAC. I would also like to compare the performance of it with CD transports.

[dangus]

The Creative Nomad Jukebox 3 had S/PDIF output. If you replaced the hard drive with a CF to IDE adapter, you could play from Compact Flash cards.

However, it doesn't seem like it would be rocket surgery to read a CF or SD card using some microcontroller, then dump wav files to an S/PDIF transmitter.

http://www.opencircuits.com/Music_Player

http://forum.microchip.com/tm.aspx?m=166133&mpage=2


This looks particularly promising:
http://dspdap.sourceforge.net/index.html
It could be possible to add an S/PDIF output using a chip like the DIT4096, since the CODEC appears to talk to the DSP using standard serial digital audio signals.

So does the Rockbox Player project:
http://www.rockbox.org/twiki/bin/vie.../RockboxPlayer

[00940]

Originally posted by audiosteve
I just checked out the Vinculum website. They have the VMUSIC 1 and VMUSIC2 modules. The schematic available for the VMUSIC 1 shows it using a VLSI VS1003 MP3 decoder chip. This part has the DAC internbal and the digital lines needed to create a SPDI/F or other digital I/F are not present. In addition, the specs on the integrated DAC are pretty crappy.

From VLSI, the interesting chips seems to be the vs1033 and vs1053. They have I2S outputs to interface with an external DAC. The bad news is that they don't seem to output anything else than multiples of 48KHz.