AD7606B相位校准导致busy阻塞的原因？

我在调试AD7606B相位校准，如果给任意通道PHASE寄存器写一个值（如CH4_PHASE=1），busy就会被阻塞。如果CH1~8_PHASE=0，busy信号正常，采集正常。

第一张图是PHASE校准都为0的情况，第二张图是CH1_PHASE=1的情况。通道3是外部PWM采集时钟1kHz（占空比50%），通道2是busy信号，通道4是spi_CS。我用的是AD7606b绿色的评估板。使用spi单线输出。
CH1~8_PHASE=0时读到的寄存器的值：
ad7606b reg1 = 0x80
ad7606b reg2 = 0x20
ad7606b reg3 = 0x 0
ad7606b reg4 = 0x 0
ad7606b reg5 = 0x 0
ad7606b reg6 = 0x 0
ad7606b reg7 = 0x 0
ad7606b reg8 = 0x 0
= 0x1F = 0x1F
ad7606b reg10 = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
ad7606b reg17 = 0x 0
ad7606b reg18 = 0x 0
ad7606b reg19 = 0x 0
ad7606b reg20 = 0x 0
ad7606b reg21 = 0x 0
ad7606b reg22 = 0x 0
ad7606b reg23 = 0x 0
ad7606b reg24 = 0x 0
ad7606b reg25 = 0x 0
ad7606b reg26 = 0x 0
ad7606b reg27 = 0x 0
ad7606b reg28 = 0x 0
ad7606b reg29 = 0x 0
ad7606b reg30 = 0x 0
ad7606b reg31 = 0x 0
ad7606b reg32 = 0x 0
ad7606b reg33 = 0x 1
ad7606b reg34 = 0x 0
ad7606b reg35 = 0x 0
ad7606b reg36 = 0x 0
ad7606b reg37 = 0x 0
ad7606b reg38 = 0x 0
ad7606b reg39 = 0x 0
ad7606b reg40 = 0x 0
ad7606b reg41 = 0x 0
ad7606b reg42 = 0x 0
ad7606b reg43 = 0x 0
ad7606b reg44 = 0x 0
ad7606b reg45 = 0x 0
ad7606b reg46 = 0x 0
ad7606b reg47 = 0x14
CH4_PHASE=1时读到的寄存器的值：
ad7606b reg1 = 0x80
ad7606b reg2 = 0x20
ad7606b reg3 = 0x 0
ad7606b reg4 = 0x 0
ad7606b reg5 = 0x 0
ad7606b reg6 = 0x 0
ad7606b reg7 = 0x 0
ad7606b reg8 = 0x 0
= 0x1F = 0x1F
ad7606b reg10 = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
= 0x1F = 0x1F
ad7606b reg17 = 0x 0
ad7606b reg18 = 0x 0
ad7606b reg19 = 0x 0
ad7606b reg20 = 0x 0
ad7606b reg21 = 0x 0
ad7606b reg22 = 0x 0
ad7606b reg23 = 0x 0
ad7606b reg24 = 0x 0
ad7606b reg25 = 0x 0
ad7606b reg26 = 0x 0
ad7606b reg27 = 0x 0
ad7606b reg28 = 0x 1
ad7606b reg29 = 0x 0
ad7606b reg30 = 0x 0
ad7606b reg31 = 0x 0
ad7606b reg32 = 0x 0
ad7606b reg33 = 0x 1
ad7606b reg34 = 0x 0
ad7606b reg35 = 0x 0
ad7606b reg36 = 0x 0
ad7606b reg37 = 0x 0
ad7606b reg38 = 0x 0
ad7606b reg39 = 0x 0
ad7606b reg40 = 0x 0
ad7606b reg41 = 0x 0
ad7606b reg42 = 0x 0
ad7606b reg43 = 0x 0
ad7606b reg44 = 0x 0
ad7606b reg45 = 0x 0
ad7606b reg46 = 0x 0
ad7606b reg47 = 0x14
读寄存器的值都是正确的，请是什么原因导致的？