Readback registers (0x0508 and 0x0809) cannot be read normally. 0x00 is always read out.Is there specific procedure?
Because 0x56 is read normally from 0x000C, I think reading register itself is working no problem.
Table 68 in the AD9528 datasheet outlines the readback functions of registers 0x0508 and 0x0509. If you confirm that register 0x000C is indeed 0x56, than that means that the SPI or I2C communication is functioning correctly. I would recommend to make sure that your settings are correct for the configuration you are trying to achieve and to ensure that all signals going into the AD9528 are as expected.
For debug, you can apply a reference to RefA and the VCXO signal. You can then monitor 0x0508 for the VCXO status indicator and 0x0508 for the RefA status indicator. These circuits are simple toggle detectors and do not require any special setup for the status indicator to function.
Once those signals are reading back correctly, you can proceed with the rest of the AD9528 setup.
Thanks to your advice, by checking commands sent from FPGA via I2C, we find some of the commands are wrong. Now we are able to get right values from readback registers.
Again, thanks a lot.Katsu
You're welcome! It's a pleasure, and I'm sorry you had difficulty.
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