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Digi+ SPDIF input?

Steve Tuck

September 23, 2014 14:22

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There seems to be space on the PCB for a coax + optical SPDIF input, which is exactly what I'm looking for (to make a digital recorder with the Pi). Have you experimented with that? I think the I2S bus could potentially support input from the WM8804.

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34 comments

• 0
  
  HiFiBerry team September 24, 2014 05:45

  Dear Steve,
  
  the driver does not support it yet. It might be a feature to add in the future, but we don't have any short-term plans.
  
  Best regards
  
  Daniel
  
• 0
  
  Petteri Markkula February 01, 2015 17:24

  Is this still the case regarding the driver support? I noticed that there is also a capture device under /proc/asound/sndrpihifiberry.
• 0
  
  HiFiBerry team February 03, 2015 10:42

  Dear Petteri,
  
  as the underlying chip driver has support for capturing, this might work. However we haven't tested this and have no short-term plans to do this. If you want to test and debug it by yourself, feel free and post the results. Other users might be interested.
  If you want to do this I can tell you what additional parts you need to solder onto the board.
  
  Best regards
  Daniel
• 0
  
  Petteri Markkula February 04, 2015 10:41

  I would like to test this. I am currently using cheap USB audio device with toslink input. Even if I can't use both input and output of Digi at the same time, it would be a win for me as I have better USB device with coax output.
• 0
  
  HiFiBerry team February 04, 2015 12:33

  In this case you can try the following:
  
  - add R15 = 75Ohm
  - add C9 = 100nF (can be also 220nF)
  - solder an RCA connector to P4
  
  start testing.
  
  Best regards
  Daniel
• 0
  
  Daniel Morgenthaler February 05, 2015 11:31

  What I have to solder for Toslink Input?
  
  Thanks and have a nice day!
  Daniel (too)
• 0
  
  Petteri Markkula August 31, 2015 10:57

  Finally stumbled on my toslink to coaxial converter. Coaxial input seems to work and output can be used at the same time. I've been
  doing software volume control with alsaloop doing the looping.
  
  Only problem I've noticed so far is that alsaloop needs to be started when there is active input for the loop to actually work. If alsaloop is started without input, it just starts and does nothing even when input becomes active. If you start alsaloop with input, it works and you can disconnect and reconnect input cable and loop just continues to work. I don't remember having this problem when I used separate USB audio device with toslink input.
  
  I didn't test toslink input, but it should also work if you connect it properly.
  
• 0
  
  HiFiBerry team August 31, 2015 11:09

  Hi Petteri,
  
  this has to do with the clock propagation. The board supports only a single clock source. This can the the onboard oscillator or the input. If you use the input, the clock is derived from here. If there is no clock on the input, there is no automatic failover to the onboard clock. Therefore if you want to use the input, you need to have a correct signal connected to it, otherwise you also won't be able to playback a signal.
  
  Best regards
  Daniel
• 0
  
  crosewarne September 11, 2015 12:52

  Hello,
  
  I'm also interested in using the optical Toslink input. The above suggestion seems applicable to the RCA input, whereas some combination of C11, R17 and R16 seem necessary for the Toslink (optical) input (C6 is already mounted on my board).
  
  Could you confirm the above, and let me know the resistor/capacitor values I need to use?
  
  Best regards,
  Chris
• 1
  
  HiFiBerry team September 11, 2015 13:02

  For TOSLink R16/R17 are a voltage divider that reduces the 5V to 1V, e.g. R16 10k, R17 2k. C9 is again 100-220nF
  Make sure you use a TOSLink receiver. While sender and receiver look the same from the outside, these are completely different parts.
  
  Best regards
  Daniel
  
• 0
  
  Oskar Joelsson February 18, 2016 14:08

  Hi, also interested. Anyone got it working? 

  And do I need to add anything to C11 for toslink rx? 

  Br Oskar 

  Edited by Oskar Joelsson February 18, 2016 15:11
• 0
  
  Søren Mikkelsen June 18, 2016 21:01

  Dear HifiBerry team.

  Could you please provide a manufactor number for the Toslink plug / inlet? Toshiba??? Which model should we use?

   

  Kind regards,
  Soren.

• 0
  
  HiFiBerry team June 19, 2016 08:57

  Dear Søren,

  the Everlight PLR135-T10 should fit. You might have a look at different Everlight PLR-types and check what other types share teh same pinout.

  Best regards,
  Daniel

• 0
  
  Søren Mikkelsen June 21, 2016 12:00

  Hi,

  Thank you so much for the response. It's highly appreciated.

• 0
  
  Andres Torrubia August 23, 2016 08:10

  Hello, I finally soldered all required components for SPDIF TOSLINK input:

  - PLR135-T10
  - R6 10k
  - R7 2k
  - C11 100nF

  I connected an optical cable outputting a 44.1k stereo SPDIF (tested on a different receiver) yet when I do:

  $ arecord -f cd test.wav
  Recording WAVE 'test.wav' : Signed 16 bit Little Endian, Rate 44100 Hz, Stereo
  arecord: pcm_read:2031: read error: Input/output errorI get an error.

  Running on a Raspberry pi 2 on 4.4.13:

  Last line of running dmesg reveals:

  [   71.996405] bcm2835-dma 3f007000.dma: DMA transfer could not be terminated

  The DMA transfer error repeats each time I run the arecord command.

  $ uname -a
  Linux 4.4.13-v7+ #894 SMP Mon Jun 13 13:13:27 BST 2016 armv7l GNU/Linu

  For those of you who managed to get spdif working, what kernel version/drivers did you use?

  Edited by Andres Torrubia August 23, 2016 08:13
• 0
  
  HiFiBerry team August 23, 2016 08:12

  Dear Andres,

  I just realized last week that the PLR135 does not work with the current board release. You might try the RCA input instead.

  Best regards,
  Daniel

• 0
  
  Andres Torrubia August 23, 2016 08:14

  Thanks for the prompt reply Daniel.

  Any other optical receiver which may work? I need to input optical not coax.

• 0
  
  HiFiBerry team August 23, 2016 08:15

  I'm not aware of one that will work with the current board design. We're working on a new design, but this won't be available soon.

  Best regards,
  Daniel

• 0
  
  Andres Torrubia August 23, 2016 08:17

  Thanks. Can you elaborate on what the issue is? 

• 0
  
  HiFiBerry team August 23, 2016 08:30

  The pinout of the PLR135 does not fit to the PCB.

• 0
  
  GJS December 02, 2016 17:39

  Do any HiFiBerry dacs have a coax and/or optical input? Thanks.

• 0
  
  HiFiBerry team December 02, 2016 17:54

  Are you looking for a Digi+ with an input or a DAC with an input? A DAC with an SPDIF input would be a normal standalone DAC. You would not need a Raspberry Pi for this.

  Best regards,
  Daniel

• 0
  
  GJS December 02, 2016 18:18

  Thanks Daniel.

  I would prefer a HiFiBerry DAC + Pro with an SPDIF input if that is available. Then I can connect my TV's coax output to the coax input on the Hifiberry DAC for when I watch TV. I believe the Hifiberry DAC will be much higher quality than my TV's on board DAC. I can also use the Hifiberry DAC, RPI combo as a music player, i.e., an all in one solution. Then I don't need to get a standalone DAC.

  My amplifier has analogue inputs only, not digital.

  Thanks,

  Jacob.

• 0
  
  HiFiBerry team December 04, 2016 08:50

  Hi,

  combining a DAC+ Pro and a digital input would not work well as the DAC+ Pro is using its own clocks, but a digital input always uses the clock from the source. Therefore there is no such combination planned.

  Best regards,
  Daniel

• 0
  
  Eddie Nolan May 11, 2017 23:21

  I just got coaxial input working on the Digi+ (Transformer version, Pi 3b). I used the method mentioned above (https://support.hifiberry.com/hc/en-us/community/posts/201843001/comments/200787012) of adding R15 75ohm and C9 100nF and an RCA connector and can confirm that it works. The only things I would add are that the surface mount part size is 0603 (1608 metric) and that I had to disable EEPROM (https://support.hifiberry.com/hc/en-us/articles/207551119-Rainbow-screen-Disable-EEPROM-usage) to get it to boot. Thanks!

  Edited by Eddie Nolan May 11, 2017 23:21
• 0
  
  HiFiBerry team May 12, 2017 05:08

  Hi,
  
  good to hear this. The EEPROM issue can be fixed by re-writing the EEPROM. However, disabling it is also ok as the EEPROM doesn't do anything to the sound card itself.
  What are you doing with the input? Do you use the card for sound processing or just to record something?
  We now also have the Digi+ I/O available in our shop that comes with inputs and outputs:
  https://www.hifiberry.com/shop/boards/hifiberry-digi-io/

  Best regards,
  Daniel

• 0
  
  Andres Torrubia May 12, 2017 06:22

  Daniel,

  Does the new digi-io driver allows the detection of the incoming sample rate? I remember I hacked my Digi to make toslink work and then customized the driver to dump the SPDIF capture registers https://github.com/antorsae/linux/commit/de332819b2226931478c2ec80b89c7425049a72e @ /proc/asound/... In my application I need to have bit-perfect capture and know the incoming sampling rate the PLL locks-in. I had mixed results and moved to a different project, but this feature would be nice.

  Best.

• 0
  
  HiFiBerry team May 12, 2017 06:31

  Hi,

  the problem is that ALSA itself requires the program to set a sample rate. Therefore, if you deal with different sample rates the only option is to dump registers and select the correct sample rate as you did it in your code - a feature that looks quite interesting. I will see if we can integrate this into the official HiFiBerry driver. 

  Best regards,
  Daniel

• 0
  
  Mahmut Hoca September 14, 2017 11:40

  Has there been any progress towards integrating this into the driver? When capturing from S/PDIF, it would be really useful for me if I knew beforehand what the sample rate of the input is.

• 0
  
  HiFiBerry team September 14, 2017 11:43

  Hi,

  right now, we don't plan to integrate this. However, if somebody wants to do this - just go on. The Linux kernel is open source and everybody who is interested can create a patch.

  Best regards,
  Daniel