Missing slave select line on MKR Zero


as far as i can see, the slave select line for SERCOM1 SPI (PA18) ist not connected to any pin on the MKR Zero board. Is ist really missing or have I overlooked something?

do you want to use the MKR as SPI slave?

Yes, of course.

You might have to use a different SERCOM then


i finally found PA18 and it is in use with the USB (USB ID). I´m a little bit confused: I understood, that one may assign different types of interfaces to different pins in the SERCOM config on the SAM. But only in per-defined groups. But that meant that the USB controlled the the SPI in slave mode in an erratic way. What did i get wrong?

That means PA18 is configured and used as part of the USB peripheral and not SERCOM1. Most pins in the SAMD can be used for multiple peripherals but only one at a time.