Today I build toslink socket and connect it to pin 13. In kodi settings I choose only S/PDIF (without Khadas Tone Control) and it is working.
Schematic from https://forum.odroid.com/viewtopic.php?t=21477
So what exactly toneboard is used for when used for S/PDIF? To pass through S/PDIF signal on black RCA connector two GPIO’s must also be set correctly. And I don’t know if anywhere in CE this is set.
What goes on in the chip is a black box. You would need the chip specs. However the spidif outs are generally not rated as line drivers and there would be the potential to fry the spidf pin if it was just a switch.
I agreed with you.but if spdif out work vim with tone board make fantastic silent music and movie player with coreelec.which can connected to any hi end setup with coaxial cable…
Yes but the toneboard is adding squat to the functionality and signal that you get from the VIM board. Its redundant. Connect to the pin 13 with a toslink socket and you have the same result.
Personally I wouldn’t like to load that pin 13 with a line as it has the potential to overload the chip generating the SPIDF signal. Examining the datasheet suggests that its simply a switch between pin 13 on the VIM boards and the RCA on the toneboard. Without a line driving buffer its a poor technical design.
I have posted a question on the Khadas forum to clear this up.
Had a look in the schematic, seems to be exotic solution for SPDIF config-mux (esp. in VIM_SPDIF_OUT mode, U20 acts as nice oscillator )
If both Mode-Pins (15&16) are not set, the default is SPDIF-In to DAC.
Finally got SPFIF out from toneboard RCA, by cutting away pins 15 and 16 from 40-pin connector, and soldering a 470 ohm resistor from (cutted) pin 16 to 3.3V pin 20.
As stated earlier, there is no buffering between the SPDIF chip output and toneboard RCA output but so far so good…
Now, I hope someday to get both SPDIF and analog sound out from toneboard at the same time.
Currently have to switch coreelec output between ALSA and KHADAS.