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ADC34RF52: How to fix the NCO initial phase

Hidemi Matsumura
Prodigy 40 points
Part Number: ADC34RF52

Tool/software:

I would like to set the NCO output phase to always be fixed when initializing the ADC34RF52.
The procedure for initializing the NCO phase is shown in Table 7-23 “Example Register Writes to configure the SYSREF MASK” on page 46 of the datasheet?
The NCO frequency is set to 0Hz.

  • 0
    TI__Mastermind 23760 points

    Hi,

    Yes, write these at the end of the device configuration to mask the SYSREF function only to the NCO phase reset. Then enable the internal SYSREF input and clear the SYSREF counter and start the SYSREF counter again. After one SYSREF edge, the NCO phase accumulator is reset. You can then re-mask the NCO to the full device by writing the SYSREF mask setting back to default (0x00). If multiple devices are being used, you'll need to write these to all devices at the same time.

    The register sequence would be this:

    ###
    main device configuration finished

    ### registers to mask all SYSREF paths other than NCO reset:
    0x05, 0x18
    0x181, 0x40
    0x05, 0x02
    0x357, 0xA2
    0x358, 0x02

    ### registers to clear and start sysref counter:
    # already on DIGITAL page from previous 0x05, 0x02
    0x236, 0x02
    0x236, 0x03

    ### registers to unmask all SYSREF paths:
    0x05, 0x18
    0x181, 0x40
    0x05, 0x02
    0x357, 0x00
    0x358, 0x00

    Thanks, Chase