#1 will not work for many reasons, but the main one being that with the comparator switch engaged, you will be pulling low when there is no spdif signal and that pin is shared with the I2S input.

#2- I will do some experiments and report back...

The consumer level spdif pin feeds a comparator, the comparator (through the switch) feeds D1 (or D2 one of those pins)

This is the experiment I have in mind (all I need is some "desire" to go and do it :-)):

Since I use TTL spdif, I don't need to use the comparator. If you need to use the comparator, you can tap the output of the comparator at the input side of the switch.

1- Use a single pole double throw switch
2- Connect Spdif and corresponding I2S to the switch
3- Connect spdif gnd and i2s gnd to BII gnd (both my spdif and i2s are from the same board, so the GND are already shared
4- Connect remaining I2S lines to corresponding BII pins

5- Select SPDIF or I2S with switch, Select SPDIF or I2S in Arduino

Edited by user Tuesday, May 10, 2011 12:37:08 PM(UTC)  | Reason: Not specified

the comparator is next to the SPDIF switch ion the BII board.

I did the experiment for switching i2s <-> spdif with a 1 pole 2 throw switch and s/w switching.

It works as I expected. Both I2S and SPDIF signals are live at all times. However you must follow a switching sequence in order to avoid noise:

Case 1: switching to spdif (i2s is now playing): s/w switch first and then h/w switch
Case 2: switching to i2s (spdif is playing): h/w switch first and then s/w switch

For case 1 if you switch the h/w switch first, you will get noise, because the DAC doesn't know you switched to spdif and the other input lines have data
For case 2 if you switch the s/w switch first, then the DAC thinks all data lines are spdif when they are not.

Thus, even thought the solution works, it is not optimal as one cannot follow this sequencing every time. However, if one does everything in s/w (that is, using a relay), then you can automate the sequence.

But if you are going the s/w mode, might as well use a 4-pole relay and switch all the lines...

Hope this helps....

I found this DIYAUDIO LINK.

OK, if the B2 works this way, then I understand the further requirement for a mux or SPDT. I was under the impression that the existing switch was a DPDT switch, which would make my life easier.

Simmonds

Hi,

I've been looking round for a digital MUX that does both i2s and spdif.

This appears to have SPDIF passthrough, and i2s goes to an internal engine which can be programmed, which probably includes coding to allow passthrough to the i2s out:
http://www.tridentmicro....M-MSP-M-Brief-10037D.pdf

My concern would be the possible introduction of phase noise and the complexity in doing this digitally. The SPDIF input could be used to feed the digital engine, don't perform A/D in it, just take the conversion to i2s and send that through to the B2.

Looks an interesting chip, but I literally only just found it shortly after reading this thread, so I cannot confirm compatibility. I will need a good long hard look at it, possibly see if I can acquire one and then have a 'play'.

I need a few more 'features' that I cannot get with a relay.