L9663 How do I send a synchronization pulse using upstream data buffer

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I want to use this configuration according to the L9663 Datasheet "Trigger via SPI with an upstream data buffer. The microcontroller sends the corresponding SPI command to send a sync pulse. Then, the sync pulse triggers the generator based on the value internally generates appropriate synchronization pulses. "But after I configure the relevant registers, I cannot detect a pulse signal that conforms to the UDB content on the PSI1/2 interface. How should I configure the parameters of the relevant registers?

I configured these registers in this order "DCR GCR1 CH_CR1 SPT UDB UDBCR CHCNT"

 

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