USB -> I2S and Analogue - diyAudio
Go Back   Home > Forums > Source & Line > PC Based

PC Based Computer music servers, crossovers, and equalization

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 29th January 2012, 11:35 PM   #1
diyAudio Member
 
Join Date: Aug 2008
Default USB -> I2S and Analogue

I've designed a very simple board around the PCM2706 IC, with analogue output (so I can use it now and hopefully remove some of the hum/noise I get from my PCs) and I2S for connection to a TDA1541A DAC I'll be making at some point in the future.

The overall footprint is slightly less than 5cm x 5cm (2" x 2"). I know it's customary to put SMD parts on one side and through hole on the other, but pretty much everything will go on the top side because I will mount this as a daughter-board to my future DAC via pins in the 3 isolated holes plus the I2S header. The mute and volume buttons are momentary push buttons I salvaged from an old car CD player faceplate.

I've designed this to be cheap. It'll cost me about $50 to make two (I got the DAC chips free as samples). All I hope to get from it is less noise than the onboard sound cards of my PCs. As such, no major design changes will be entertained at this point.
Attached Images
File Type: jpg schematic.jpg (92.4 KB, 477 views)
File Type: jpg top.jpg (129.6 KB, 457 views)
File Type: jpg bottom.jpg (63.1 KB, 433 views)
File Type: jpg board.jpg (128.1 KB, 422 views)
__________________
Tyler

Last edited by Redshift187; 29th January 2012 at 11:40 PM.
  Reply With Quote
Old 30th January 2012, 12:06 PM   #2
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Ground planes, those skinny ground tracks aint gonna help with noise. Seperate the digital and analogue sections, ie make sure no digital tracks go near the analogue tracks and visa verso, and try and get as much ground pour on top and bottom layers with plenty of gnd vias joining the layers, one plane.
USB d- and d+ are differential signals and best routed as a differential pair.
You have numerous traces coming out of single SMD pads and numerous acid traps, that could do with tidying up.
Capacitors for crytals want moving and routes tidying up and being direct through the caps and resistor, with a gnd guard ring around these routes.
And the power supply routes could do with thickening up a bit.
  Reply With Quote
Old 30th January 2012, 02:57 PM   #3
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
USB guidlines:
http://www.smsc.com/media/Downloads/...tes/an1517.pdf
http://www.cypress.com/?docID=32407

A bit on acid traps:
What is meant by Acid Trap? - Cadence Community
There is another reason to avoid them, not a widely detailed, but whn the manufacturer applies etch compensation to the artwork, these narrow areas can become filled with copper and wont etch out, causing an enlarged pad and possibly other problems, a neat and tidy design is always prefferable.
  Reply With Quote
Old 30th January 2012, 03:16 PM   #4
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
A little picture showing traces exiting SMD pads as an example.
Attached Images
File Type: png layout11.png (66.4 KB, 377 views)
  Reply With Quote
Old 30th January 2012, 05:12 PM   #5
diyAudio Member
 
Join Date: Aug 2008
Thanks for the advice Marce, looks like I have more work ahead. Obviously my first SMD design.
__________________
Tyler
  Reply With Quote
Old 31st January 2012, 01:52 AM   #6
diyAudio Member
 
Join Date: Aug 2008
Here are my changes. I changed the USB connector from a mini B to a B for the more flexible pin arrangement. I moved the LED to the SSPND pin for more information, I lowered some of the capacitance since I had too much for a bus powered application, plus tried to take most of the advice given by Marce.
Attached Images
File Type: jpg schematic.jpg (88.9 KB, 102 views)
File Type: jpg top.jpg (140.8 KB, 92 views)
File Type: jpg bottom.jpg (75.1 KB, 62 views)
File Type: jpg board.jpg (126.5 KB, 52 views)
__________________
Tyler
  Reply With Quote
Old 31st January 2012, 05:16 AM   #7
diyAudio Member
 
Join Date: Aug 2008
Oops, ignore that large space without fill under the USB. I moved the connector in and forgot to move the restrict I made around the data lines.
__________________
Tyler
  Reply With Quote
Old 31st January 2012, 10:26 AM   #8
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Much better and neater.
Could do with more vias between gnd, will reply more in detail later
  Reply With Quote
Old 31st January 2012, 11:15 AM   #9
marce is offline marce  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Location: Blackburn, Lancs
Try and get some GND pour between C2 pad and R11, just in case. I have seen traces near clock traces suffer from crosstalk, which can be interesting especialy on a reset pin
  Reply With Quote
Old 2nd February 2012, 04:45 AM   #10
diyAudio Member
 
Join Date: Aug 2008
No schematic changes this time.
Attached Images
File Type: jpg 3top.jpg (169.3 KB, 45 views)
File Type: jpg 3bottom.jpg (92.0 KB, 32 views)
File Type: jpg 3board.jpg (153.6 KB, 30 views)
__________________
Tyler
  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
Best USB->I2S Option? ebinal PC Based 40 21st February 2012 09:12 PM
USB -> I2S circuit questions sfasf Digital Line Level 7 30th November 2011 06:50 PM
Direct Wiring a DDDAC USB-->I2S to a P3A DAC I2S DIN input dkj7a Digital Source 1 26th March 2006 05:46 PM
Pcm2707 Usb->i2s Rocky Digital Source 0 21st October 2005 01:35 AM
PCM2707 USB-->I2S how to use etc. nl Digital Source 4 5th August 2005 12:29 PM


New To Site? Need Help?

All times are GMT. The time now is 08:28 PM.


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