Development board sync with WC

[soall]

Hey,
I'm totally new to DIY and I'm considering getting a development board for some digital audio hardware projects. However i'm concern with the integration in a studio.
Is it possible to synchronise the system clock of a development board to the word clock of an audio interface ?
If you have any infos, docs, advices on the subject It will make my day
best,
soall

 

[Markw4]

Word clock is the same rate as LRCK. It is meant to be sent around a studio to synchronize clocks, but is probably not the best way with most modern equipment. Following word clock takes a PLL, but PLLs, and Word Clock never work as well as maybe other approaches, and that is because of WC jitter issues. For A/D converters, best to just make them the master, so long as they have a good clock. If they don't have a good clock, probably need a better A/D. For dacs, Sabre based dacs and most other dacs in todays studios can sync incoming SPDIF or AES audio to their internal low jitter clocks using ASRC technology. Usually, that will give better sound quality than Word Clock. Texas Instruments SRC4393 is commonly used part that has distortion rated down at -140dB. It may be the best solution for interfacing two different clock domains. So, unless you have some legacy data converters or other equipment that can't function in your system without Word Clock, I would recommend not using WC for anything. All IMHO, of course.

When you say you want to do digital audio hardware projects with a development board, could you be more specific about you have in mind? Is there some reason why you anticipate needing WC?

 

[soall]

Hey Markw4,
Thanks for the answer,
Actually, what I want to do is to drive an AD75019 chip from a development board to create a digitally controlled audio matrix.
The thing is that I need the matrix to be in sync with the rest of the studio, so I'm looking for a way to slave it.
Best,
Soall

 

[soall]

Hey rfbrw,
Yes, I want to route analog audio. I would like to control the matrix digitally from the development board and if possible synchronously with my DAC.

 

[rfbrw]

Not sure how much synchronisation will help with analogue audio but you will need more than a vcxo/pll setup. You will most likely need a microcontroller to load the 256 bits that control the matrix.
74HC4046
Dean's PLL Book

 

[soall]

Hey thanks for the docs,
Yes, I plane to use an STM32F407-based board from Olimex to load the 256 bits and to bring back PCLK high when shift registers are full : STM32-E407 - Open Source Hardware Board .
So, in order to have the change in the matrix state sync with my DAC (to bring PCLK high on a clock tick), I will need to find a way to match the STM32 frequency to a multiple of my DAC WC in phase, is such thing possible ?
Best,

 

[AIM65]

As said by rfbrw, the need to sync matrix switching with Word clock is not obvious as this is an analog matrix.
But, to do so you need external sync; syncing through the UC may be hardly predictable.
Using a flip flop allow you to produce the required negative pulse on PCLK (see datasheet) aligned on LRCK. To do so generate, by software at the end of the SPI transmission a low to high pulse on the GPIO, with minimum duration of one LRCK period plus some ns.
Use STM32 SPI interface to load data into AD75019.