In the datasheet of ATSAMD20J18 it states the following:
7.3.2 I/O Pins
After power-up, the I/O pins are tri-stated.
As far as I know, a tri-stated pin means that the pin on power-up of the processor goes to high-impedance state (not low or high). On the processor in my designs, I sometimes connect either an SD card interface or an SPI flash. Does that mean that I should connect the CS (chip select) pins of these to pull-up resistors? If not, is it possible that I might clock random data from the pin into the SD of SPI flash chip?
So far, I was never connecting pull-ups on CS and it didn't seem to had any problem. After power-up I was first enabling the internal pullup. Maybe I face a problem in the future and I will not know of it?
Thank you very much.