SPDIF RX and TX at one time on L8A-64

[Dohny]

Hello, I'm using Audio reference Design 2.0 firmware for my custom XS1-L8A-64 USB audio, but now I need SPDIF RX and TX at one time, I don't need I2S or anything else, just duplex SPDIF (+ MCK IN for SPDIF TX). Please, is there any way to do that? I think XMOS device doesn't have enough cores for that.

Thanks very much

[infiniteimprobability]

I'm afraid I2S is a pretty integral part of the reference design - it handles clocking etc. so is non-trivial to remove, so disabling I2S drive doesn't buy you much.

SPDIF input will require it's own core, but then you need to regerenate the clock somehow (whole design will need to be synchronous to any digital input). So you will need a hardware PLL to make a clean clock and something to control that - it's what we do in the L16 ref design.

Long and short is that you don't have enough cores on an L8 to do this, because the max number is 6 to achieve the 80MIPS required by XUD. USB Audio + SPDIF out is 6, so you are a couple short.

The L16 reference design does what you need though (and much more) - so there is a solution!

[Dohny]

Thank you,

we can't use L16, because it isn't in TQFP, only QFN with "internal" connection and we don't have reflow oven.

I'm going to use SPDIF RX IC (AK4117).

[Ross]

You could put down 2 TQFP parts ;)