The SPI bus of the VNI8200 allows the daisy chain configuration, in other words, several VNI8200 can be put on the same bus. The daisy chain allows to save a lot of pins on the microcontroller. With 36 actuators in parallel mode, 36 pins of the microcontroller are necessary. In fact, even more if diagnostics are used. Thanks to the daisy chain configuration of the SPI bus, only 4 pins are necessary.