24 bit I2S source to 16 bit DAC? - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th June 2005, 08:20 PM   #1
diyAudio Member
 
Join Date: Jun 2004
Location: Connecticut
Default 24 bit I2S source to 16 bit DAC?

Since I managed to get a free Revolution 7.1 sound card, I have been entertaining the idea of tapping the I2S directly out of the Envy24HT IC. I have found the datasheet for it and the right pins, but as the EEPROM is set at the moment it is configured for an AKM DAC and outputs 24 bit left justified I2S.

This would not be a problem except as a quick and cheap experiment I wanted to go right into the dreaded TDA1543, which of course is 16 bit. The datasheet for TDA1543 says it "accepts input serial data formats in two's complement with any bit length". However, the only timing diagram example shows a 16 bit input. I would be using it for only 16 bit pcm so I would think the Envy24 pads the rest of the word with zeros. Somehow though, I don't see how this could work. Is there any way to basically trim the zeros without editing the EEPROM to set the output to 16 bit to start? I guess you could demultiplex the serial data and use some logic but if that is the case I might as well just go DF1704 - PCM1704 to start.

Thanks,
Chris
  Reply With Quote
Old 16th June 2005, 10:46 AM   #2
diyAudio Member
 
Join Date: Jan 2004
Location: rouen
Send a message via ICQ to apolon34
I

I think tda1543 only accept EIAJ input so you need to convert i2s to eiaj first. The additional bits shouldn't cause any trouble because (if I remember well) i2s containt 64 bits data
  Reply With Quote
Old 16th June 2005, 12:30 PM   #3
diyAudio Member
 
Join Date: Jun 2004
Location: Connecticut
I think only the "A" chips are EIAJ? At least the datasheet says I2S.
  Reply With Quote
Old 16th June 2005, 12:46 PM   #4
Bricolo is offline Bricolo  France
diyAudio Member
 
Bricolo's Avatar
 
Join Date: Nov 2002
Location: Grenoble, FR
TDA1543 : I2S
TDA1543A: EIAJ
__________________
Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease
  Reply With Quote
Old 16th June 2005, 05:09 PM   #5
diyAudio Member
 
Join Date: Jun 2004
Location: Connecticut
Just read the I2S bus datasheet.. should have thought to do this before posting .
  Reply With Quote
Old 18th June 2005, 05:24 PM   #6
diyAudio Member
 
Join Date: Jul 2004
Location: Prague
Send a message via ICQ to Glassman
it will work just fine, use software player, that can dither/noiseshape to 16bit if you'll be using volume control, like foobar2000 if you don't use it already.. if the bitclock is 64Fs, each channel carries up to 32bits of data, if it's just 32Fs, then only 16bits per channel.. you have 64Fs running on the soundcard, I hope the TDA can take it, I see no reason why it shouldn't..
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Source follower and common source output stages slogan2112 Pass Labs 2 9th October 2008 08:19 PM
Aleph-type current source, but source follower this time tschrama Pass Labs 4 29th July 2005 12:55 PM
Source follower electret mike -> use with current source? capslock Solid State 1 28th February 2003 12:54 PM
Source of AKM and NPC? maczrool Digital Source 0 6th October 2002 08:49 PM


New To Site? Need Help?

All times are GMT. The time now is 09:40 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2