Thanks in advanced. Based on nRF5_SDK_17.0.2, I can use i2c with icm42670p normally. Due to power consideration, I need to r/w this imu with spi either to decide which is the lower power design. But what makes me confused is: I can r/w icm42670p's register with spi normally, but always get wrong MCLK_RDY value(in function: inv_imu_switch_on_mclk, icm42670p eMD). I noticed that AN-000352 is mentioned when use spi interface, but unfortunately I can't find this sheet. Would any experts tell me how to get it? Or point out what key steps I missed directly. I will provide more details if needed. Thanks again.