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AD9956-VCO writing to register

Question asked by michael10 on May 19, 2017
Latest reply on May 23, 2017 by mcee



I am attempting to have a TI MSP432 microcontroller communicate with the AD9956 via the SPI protocol. I have coded three iterative messages, where the first two attempt to write to CFR1 and CFR2 registers, while the third message writes to PCR0 (0x06), with its data being 0 phase and a specific frequency tuning word. I have confirmed the output signal from the MSP432 is correct, assuming that no time delay is necessary between sending the instruction byte and the actual data to the DDS. Is this assumption correct?


I do not unfortunately currently have the capacity to read from the DDS' registers. Earlier today I ensured the DDS was working by controlling it via PC software.


My code is attached below, and I can attach a screenshot of the logic analyzer screen depicting the output waveform if desired. Any help would be appreciated. In addition to the standard SPI protocol, three bits are assigned to be digital low to ensure the DDS chooses PCR0 as the active frequency register.


Please note: The code's name is vestigial, and does not perfectly correlate with the given TI sample code.


Thank you for your time.