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ADAU1467 EEPROM Update and MCLK Source

Question asked by mike.baker Employee on Apr 19, 2018
Latest reply on Apr 23, 2018 by DaveThib

I'm using the ADAU1467 processors for an audio switching matrix with 32 inputs and 16 outputs. There are 8 ADAU1979 ADCs and one ADAU1966 DAC. I have a few questions regarding booting and the clock input.

 

 I plan on operating the ADAU1467 in standalone mode, but I’m unclear on the EEPROM update process in that configuration. The evaluation board has the USBi adapter which uses an 8051 microcontroller and proprietary firmware to interface with SigmaStudio and write EEPROM contents. First, data is written to the 1467 as an SPI slave and then the 1467 writes that data into the EEPROM as an SPI master. In SigmaStudio this function is described as “Write Latest Compilation through DSP”. Is there a simple way to include this functionality on my board without adding the 10-pin header and using the USBi adapter?

 

Given that the ADAU1979 devices only have 2 configurable I2C address bits, and the ADAU1467 only has one master I2C port, I see that I can only control 4 devices via I2C and the other 4 devices will need to be in standalone mode. Using the pins defined in table 14 of the datasheet and the default register settings, I can operate using TDM8 at a 48KHz sample frequency, with the standalone devices using slots 1-4. I can then configure the other 4 ADAU1979 devices to use slots 5-8. What I’m not sure about is how to use the MCLKIN pin. From the datasheet:

 

The CLK_S bit (Bit 4) of Register 0x01 sets the clock source for

the PLL. The clock source can be either the MCLKIN pin or the

LRCLK pin (slave mode).

 

I intend to select the LRCLK pin as my PLL input on the four I2C controlled devices. In that situation do I tie MCLK to ground?

 

As for the standalone devices, the default value of this bit is 0, which selects the MCLK pin as the PLL source. Is this bit effected by the ADDR1 pin in standalone which sets the SAI mode to slave? If not, do I need to supply a 12.288MHZ clock on MCLKIN from the ADAU1467?

 

Thanks for the support...

 

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