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ADAU1701 I2S, PCM

Question asked by drzerog on Mar 29, 2011
Latest reply on Apr 4, 2011 by Abi

Have several questions regarding output of I2S on an ADAU1701. To be clear, the board is one of our own, however, the schematic is as shown on Pg 51 of the datasheet (I2C control) without any of the DAC wiring and PLL mode 0 and 1 tied high.

 

1) On the inputs, there is a selection as to what type of serial data (I2S, LJ etc), however, on the output section of the serial data, there is no similar box. If I want to input Right Justified PCM and output to I2S is there any way I can do this?

 

2) I've been trying to use the ADAU1701 as a master clock driver, however, the external chips I am using behave poorly at the clock signals that I am generating. The clock transitions are clean, however the lowest frequency I can obtain is about 767kHz (12.28MHz/16) is this correct?

 

3) So to circumvent the problem, I change the external chip I am using to master mode, however, the ADAU1701 doesn't seem to recognise the external clock until I wire the output pins MP11 (output b_clk) to MP5 (input bclk) and MP10 (output lr_clk) to MP4 (input_lrclk)? Is this correct? As I pass the output signal back to the chip, it has trouble recognising it, thus I am uncertain whether or not the format is incorrect (q 1 above) or if the clock is being processed incorrectly.

 

Thanks in advance for anybody's help

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