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Clock Powerup timing

Question asked by philipj451 on Nov 16, 2017
Latest reply on Nov 22, 2017 by DaveThib

I have a design using ADAU1452 processor, the power for which may be turned on/off by a control CPU. The XTALIN pin is driven at 24.576MHz from an FPGA which also runs from the same on/off power lines as the ADAU1452.

 

My first question is:

Is it OK to power up the chip and then apply the XTALIN clock signal a short while later? It takes a second or two to program the FPGA and only then does the clock get established.

 

2nd question:

I am using the SPI slave interface to load the program etc. Is there a suitable register I can read before I do this that will contain a known value to confirm the chip s powered up and running? At the moment I am reading PLL_CTRL0 (address 0xF000) which says in the data sheet should have a reset value of 0x0060 but I am getting 0x0000...

 

Thanks anyone for any advice you can offer

PhilipJ

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