The following Figure shows how two DRV81646 devices can be connected in daisy chain to leverage GPIO/ isolation saving. SDO pin of one device is fed to the SDI pin of the following device in the chain
To write to two devices , 8 bits of data need to be written as shown in Figure . Note SDO is sent out on Negedge of SCLK. SDO is ready to be sampled on following posedge of SCLK. The value on SDI pin is also sampled on posedge of SCLK. Note Latch need not be brought low to initiate a shift in of data. A posedge of Latch is needed to Latch the data shifted in to Outputs.