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ADAU1446 and AD1938/9 clock and programming

Question asked by grimbart on Sep 24, 2013



I bought the ADAU1446 Evaluation board and it works fine (except some trouble with noise/rustle/crackle - it will be another tread and i will do some tests...) . Now, I'm drawing my own schematics (3 analog inputs and 5 analog outputs; some filter processing) and I have two questions about the connection between the ADAU1446 and the CODEC (1938 or 1939, which one is not important for this issue, I think).


1) MasterClock: I would connect a crystal to the ADAU1446 as shown in the attached picture and use the DSP as Master. For the SDATA in and out, I should use the ABCLK, ALRCLK and DBCLK, DLRCLK respectively, right? The CODEC synchronizes the audio signal with this two clock signals. Nevertheless, I have to connect the CLKOUT from DSP to the MCLKI of the CODEC for additional synchronization? I have to connect any other pins or components for synchronization purpose between the two ICs (of course the PLL and XTALI/O circuits are needed)?


2) CODEC programming: When I took the Eval-board the first time in operation, it worked well without including a ADAU193x in the Hardware Setup of SigmaStudio. I have to provide the SPI connection to the CODEC in my schematics? If yes, than connect to the USBi connector or to the ADAU1446 SPI ports? I really don't understand how it works... If I want to make a selfboot system, I have to change the programming interface for programming the CODEC (only SPI supported) and the EEPROM (only I2C supported)?

How can I change the sampling rate without reprogramming the CODEC? (I have read FAQ: How do I change the sample rate of my SigmaStudio system? and an other discussion I cannot find now about this topic, but it isn't still clear)


Thank you in advance,