I2S to COB format converter? (PCM54P dac)

[Milen]

Hello,

I want to try PCM54 with XMOS USB transport, but it supports only parallel input data. Tried search, nowhere found an schematic what I should do to take out parallel data from i2s... And how does it work the protocol, in i2s there is LE signal, that enables the output, but there is only data bits. Is there some code or string on MSB or LSB pin, that enables the output, or something else? I can make a matrix with counters, D-triggers and AND logic to make parallel data for the DAC, but don't know how does it will work...

Regards,

Milen

 

[lcsaszar]

If I remember correctly, there was a circuit by Pedja Rogic found on the web (perhaps also on diyAudio, search for it), that did I2S to simultaneous conversion. I did not build it yet, but it is on my years-long to-do list 🙂

 

[Milen]

I found how does it works... Every single bit change appears to the output, it also need deglitcher... Now I am thinking about control logic, I decided to use it with XMOS, SM5804 in parallel mode and two PCM54P DACs.

 

[percival007]

iancanada on here has designed a great PCB which does what you want..........
Drive NOS AD1865/62,PCM1704/02/63,TDA1541 from FIFO: Universal I2S-PCM driver board

I can confirm it works really well with TDA1541's so I suspect it will be great with the PCM54

P.

 

[canvas]

iancanada on here has designed a great PCB which does what you want..........
Drive NOS AD1865/62,PCM1704/02/63,TDA1541 from FIFO: Universal I2S-PCM driver board

I can confirm it works really well with TDA1541's so I suspect it will be great with the PCM54

P.

Nope. Ian's board is still serial output. PCM54 needs parallel input data stream.

 

[AIM65]

I2S receiver

Hi Milen,

The attached Philips paper provide some insights and also and implementation diagram for a I2S receiver with parallel output.

Chris

 

[Milen]

AIM65 , thanks! That's very helpful for me!

 

[percival007]

Found these sbhematicsa on-line.
How about using the Ladder DAC schematic without the Resistors, that's parallel Data isn't it? (Albeit 18 bits and Mono I think, could be modified for 16 bits if that's what the PCM54 is.)

And then the other circuit could be the drive to get two channels from one i2S source.

Just a thought?

 

[Trajan]

For 2’s complement to COB, you need to invert all the bits except the MSB, I believe. If you have the serial data, feed it into a serial to parallel shift register(s) and then invert the necessary bits with inverters and feed the DAC at the right time. The kits above are 2’s complement, but could be stage 1.

 

[lcsaszar]

And I found this on-line:

Discrete DAC

Schematics

You will also need a deglitcher, can be realized by using FETs or S/H IC.

 

[percival007]

For 2’s complement to COB, you need to invert all the bits except the MSB, I believe. If you have the serial data, feed it into a serial to parallel shift register(s) and then invert the necessary bits with inverters and feed the DAC at the right time. The kits above are 2’s complement, but could be stage 1.

Inverting just the MSB would also work I think.

P.