DRV8908-Q1: Daisy chain control

Tool/software:

Hi,

I'm tying to control two DRV8908 in daisy chain mode. There is only an example of three DRV89xx in daisy chain mode in the datasheet and there is no detailed timing chart. In my prototype something is not right. Please help to check if the command is sent correctly to the daisy chained DRV8908.

I'm using 3.3V as logic supply so all the logic signals are 3.3V.

I use 16 bit SPI transmit with 1MHz clock. The data is sent MSB first.

In my test the Operation control register (address 8) is written to the two devices, with 0x00 and 0xFF, in the following sequence,

Header 0x82A0

Address 0x0808

Data 0xFF00

However when I read the data it shows 00, 0x40.

Thanks.

SP Lee