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AD9576 programming problem via SPI

Hi, Im Juan.

I need to program the AD9576 via SPI, so I have set pins 22 and 49 high for this purpose. For the configuration of the registers I have used the ACE software, I have selected the reference correctly (ref1 = CMOS 200 MHz) and the outputs enabled but still nothing is displayed at the output. My biggest doubt is that the instruction word is not being sent correctly. My method is to configure the single instruction first through register 0x001 (SPI configuration B) and then update through register 0x00F (I/O update) and start sending address followed by data. It is worth mentioning that I do this by sending 8 byte packets and I don't know if this is a problem. I would like to know if there is a bug in this communication method.

Regards,

Juan Camilo Peña A.

  • Hi,

    "I send 3 bytes, the first and second has the register address in read mode, the third one byte contains a 0x00, this is a dummy byte to have the SCK one more byte, to return the default value. But the voltage of the data read was of 1V."

    I believe sending 0x00 as the 3rd byte creates a contention with the AD9576 trying to send the register value back to the controller. There must be a SPI setting in the controller that allows you to send a clock to the AD9576 on the SCLK line without putting a byte on its SDO line.

    Petre

  • Hi Petre,

    I can write and read all the AD9576's registers and now I can get the desired outputs. 

    Thank you so much for your help.

    Best regards,

    Juan Camilo Peña A.