Forum Rule: Always post complete source code & details to reproduce any issue!
Page 2 of 2 FirstFirst 1 2
Results 26 to 42 of 42

Thread: CS42448 board update for T4 pinouts and improved performance

  1. #26
    Senior Member+ Frank B's Avatar
    Join Date
    Apr 2014
    Location
    Germany NRW
    Posts
    6,874
    Quote Originally Posted by neurofun View Post
    Just for the sake of correctness.
    Your statement is only valid for T3.x.
    On the T4.0 the audio lib runs @ 44100Hz.
    ... and it supports any other frequency. 48kHz should work, with minimal jitter, but I have not tested it.
    48kHz is interesting, so if there are any problems I'm willing to help to solve that.
    Last edited by Frank B; 01-10-2020 at 12:02 AM.

  2. #27
    Quote Originally Posted by palmerr View Post
    Thanks Mhelin for the commentary,
    One part of the circuit I'm not yet happy with is the 5V power changeover from VUSB to external. I've simply left it that you shouldn't plug both in a the same time. Not very elegant. I originally included a jumper, as it merely duplicated the "don't plug both in together" instruction. The only other solution I can think of would be a power management chip, but this would be better on the Teensy board than a daughter board.
    What if you just required that the board is powered only using USB, a phone charger for an instance when it's not connected to PC, or connect the +5V socket to VUSB pins (on teensy) directly, they are directly connected anyway. Teensy 4.0 VIN is +5V. You could of course use a small 5V relay which disconnects VIN supply when VUSB is connected.

  3. #28
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    Neat idea - I hadn't thought of using Teensy's USB as ext pwr - simplifies that things a bit, and we're unlikely to get anywhere near the 1A limit (or even 500mA) of a phone charger.

    As for the relay (or FET) - it's at least another 5 components. I've culled a lot of nice features to keep complexity and board size down, so probably not, this time around.

  4. #29
    Member
    Join Date
    Aug 2019
    Location
    Melbourne Australia
    Posts
    88
    Watching with interest.

    Any thoughts of solderable bow-tie jumper arrangement to allow use on T3x?

  5. #30
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    Thanks for the bow tie suggestion - it's saved some real estate and allowed "normal" operation OOB on the inputs and outputs.

    While, I'm not trying for T3 / T4 compatibility on this iteration (first prototype), maybe later. There's plenty of real estate under the Teensy to allow for this, if needed. I've taken the view that Paul's version works with T3s, and that the sample rate differences between T3 & T4 make synchronizing digital connections between T3/T4s a pain (dropped or extra packets), that everyone will move fairly quickly to T4's, particularly if Paul does some T4.x's with extra pins someday (I'm personally not a fan of the Teensy's underside pads).

    Here's the current state of the schematic and board layout.

    @mhelin - I've decided to keep the AUX_ADC header, as I think some one who wants 6 inputs is more likely to want 8 than some of the other features I've had to forgo. As for a long MCLK degrading over distance - good point - I was thinking of a direct plug daughter card, rather than a ribbon cable, to keep signal line short.

    I've kept the I2C, as some of the preamp designs I have in mind have digital pots for gain control.

    I've combined all the ext power inputs into a single header. Possibly a pain with Ext 5v/USB powering and +/-V as well. I've kept a separate EXT_5V header just in case.

    Board size is 109 x 90 - so within the Eurorack limits.

    I'm getting to the point where I'm thinking about price points - as I suspect many more people would adopt a board populated with the basic components (everything except the LM358, shrouded I/O, ext power and I2C headers?) I can't see that I can get anywhere near the cost of Paul's SGTL5000 board - particularly with a small run.

    $A40 BOM ($10 of this is the 3.5mm sockets)
    $A17 - board, assembly and shipping, run of 20.

    That brings the cost to $A56 (or $A46 without 3.5mm sockets), before overheads, postage etc. So the retail price would be around $A60 without sockets, and $A70 with. What do you think?
    Attached Files Attached Files
    Last edited by palmerr; 01-11-2020 at 04:11 AM.

  6. #31
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    I felt bad about saying the jumpers for T3 / T4 could be a later addition.

    Updated schematics and layout attached, with T3/4 jumpers included.

    Please check my pinouts for both T3 & T4.
    Attached Files Attached Files

  7. #32
    Member
    Join Date
    Aug 2019
    Location
    Melbourne Australia
    Posts
    88
    Hey thanks for running with the idea. I'm not up to speed with all the details of which pin goes where yet. Been mulling over building a Teensy synth incorporating some tricks I used in a self-build in the late '70s. Starting the audio design tool tutorial in the near future after installing some holes.

  8. #33
    Quote Originally Posted by palmerr View Post
    I felt bad about saying the jumpers for T3 / T4 could be a later addition.

    Updated schematics and layout attached, with T3/4 jumpers included.

    Please check my pinouts for both T3 & T4.
    BLCK is still connected to wrong pin D22 it should go to D21.

  9. #34
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    Many thanks. BCLK fixed now.

    Will republish in a few days after others have had a chance to comment.

    Hope to send of the boards for a prototype (board only) run for completion before Lunar New Year takes my Chinese PCB house offline for a couple of weeks.

  10. #35
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    I've finally got the prototype PCBs back and loaded, and the initial results are not too bad: 80dB S/N and .0058% THD.

    With some rerouting of MCLK (shortening its path and moving it further away from any audio lines) and adding the magic 100 Ohm resistor in series, I hope to improve the noise figures.

    The final version will have provision on board for an CS5343 ADC to provide the two AUX inputs, bringing the total to 8 in - 8 out.


    Noise: Click image for larger version. 

Name:	noise.png 
Views:	11 
Size:	8.7 KB 
ID:	19162

    THD: Click image for larger version. 

Name:	thd.png 
Views:	16 
Size:	8.5 KB 
ID:	19163

    Layout: Click image for larger version. 

Name:	v3 CS42448 Board.PNG 
Views:	14 
Size:	87.2 KB 
ID:	19164

  11. #36
    Looks good. I have a couple of questions...

    1.) What was your test method (and equipment) for the above results?
    2.) Did you happen to test DC signals as well?
    3.) Which EDA software do you use, and do you plan to release the sources or just the gerbers?

    Thanks for the update.

  12. #37
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Posts
    21,807
    Quote Originally Posted by palmerr View Post
    I've finally got the prototype PCBs back and loaded
    Any chance for photos?

  13. #38
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    Test approach:
    • Focusrite Saffire Pro as test set (> 105dB S/N; < .01% dist in loopback test.)
    • RightMark
    • 1.8v p-p signal (-3.8 dB from clipping - so I could claim another 4dB S/N)
    • One channel driven, others shorted to ground (AC coupled)
    • CS42448 settings "out of the box" (i.e. high pass ADC filters still in place if Paul programmed them that way).


    DC not tested, but allowed for by headers and jumpers. Library code would need modification to turn off HP filter.

    Created in Eagle. Happy to release schematic, gerbers and BOM, not sure about releasing board routing files as I may do a production run if Paul thinks there's a market for it (as a service to the Teensy community, rather than as a profit-making venture).

    You are welcome to one of the bare prototype boards (only two wire jumpers needed) or one of the next version boards when I get to them (they will have the CS5534 on board, unlike version 1). It's always nice to have someone else testing your work! (Same goes for any of the folks who provided useful suggestions during the initial design.) The BoM cost about $75AUD including all the headers and jacks.

    Image is my testbed board, with pins instead of jacks and proper headers:
    Click image for larger version. 

Name:	cs42448 v2.jpg 
Views:	41 
Size:	180.6 KB 
ID:	19183
    Last edited by palmerr; 02-25-2020 at 09:44 PM.

  14. #39
    Instead of CS5343, why not pick an ADC that's balanced, like the other 6 inputs? Just a thought.

  15. #40
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    Yeah, that could be an idea.

    Board real-estate is very tight with the extra chip on board (and I'm trying to keep within the Eurorack limits), but I'll see if I can fit the extra pins & components.

    Any suggestions of appropriate ADCs?

  16. #41
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    To answer my own question - the CS5361/5381 seem to be candidates - with no others at reasonable cost and in reasonably small packages (TSSOP 24 or less) from other manufacturers.

    I'm not sure if I can fit the larger TSSOP 24 (7 x 8mm) package on the board in place of the current TSSOP 10 (3 x 5mm) for the CS5343, but a first glance at the specs look OK.

    One upside of the 5361 would be 0.65 mm pin spacing, rather than 0.5mm on the 5343 which is a real accuracy test for PCB loading and soldering!

    Sadly, the unit price of the slightly better spec'd 5381 is prohibitive ($42 AUD), leaving the 5361 as a candidate ($17 AUD). However it is still much more expensive than the CS5343 ($6) and on par with the CS42448 ($17).

    All in all, I don't think it's the best value to upgrade - and I'm unsure how many people would use the differential inputs anyway. If the use was professional audio and we were looking for the best CMRR/noise performance at 24 bits, then the upgrade would be worthwhile.

    On balance, I'm retaining the CS5343 for at least the next version - with 6 channels fully differential and the last 2 single ended. Thanks for triggering the thinking, if this board takes off, then the Mk III version will definitely get the upgrade!

    BTW: I haven't published a schematic for a while. I'll upload one after I get the file size below 2MB!
    Last edited by palmerr; 03-03-2020 at 01:19 AM.

  17. #42
    Senior Member
    Join Date
    Aug 2016
    Location
    Australia
    Posts
    143
    Here are the schematics as promised - the max PDF is 1.43MB so three files!

    cs42448 schematic v6-1.pdf

    cs42448 schematic v6-2.pdf

    cs42448 schematic v6-3.pdf
    Attached Files Attached Files

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •