I2S between AD1401 and AD1940 eval boards

Hi Bob,

That sounds like an interesting experiment. Yes, your I2S wiring table looks correct to me. You don't need to connect the DVDD signals, as you correctly showed in your table. Just connect the signals and at least one ground. Preferably, you could use some kind of ribbon cable with corresponding grounds for each signal to get the best signal integrity.

The USBi mod described in the link you referenced will only work (without modification) in I2C mode. To operate multiple SPI slaves, you could do one of the following:

• Power up both of the boards and program one SigmaDSP using one SigmaStudio project. Then disconnect the USBi, connect it to the other board, load a second SigmaStudio project, and program the second SigmaDSP. This is the least complicated solution.
• Do the mod described in the link you referenced to get the same ribbon cable connected to both boards. Additionally, run a fly-wire from one of the USBi's extra slave select signals to the second board's slave select line, and sever the ribbon cable's slave select line so that it doesn't reach the second board. You basically need a separate slave select line for each board. Then, you can use one SigmaStudio project to program both boards, but you need to choose different slave select lines in the USBi's drop-down menu for each IC.

More information about the USBi's pin-out and extra slave select lines is available in the EVAL-ADUSB2EBZ app note: http://www.analog.com/static/imported-files/application_notes/AN-1006.pdf

I would suggest the first option, since it doesn't require hacking any hardware.

Brett

     Hi Brett,

     Thanks for your help!  I will program one board at a time as you recommend.  Mostly I just need to get some experience with I2S, because the next project here will combine several I2S-connected DSPs in a mixer.

     Bob