Why shouldn't we use PIN24 as the NSS pin?

[ccb23]

mfrc522/examples/rpi.rs

Line 5 in 40ffdb4

//! IMPORTANT: Do *not* use PIN24 / BCM8 / CE0 as the NSS pin

[ccb23]

I do not get your advice: Why is it important not to use PIN24 as NSS pin?

[fridtjof]

PIN24 is a Chip Select pin triggered by the SPI driver itself. With SPI, whenever you want to exchange data, you have to signal to a chip you want to talk to it through this.

I assume there is something wrong or broken somewhere with the standard behavior of this pin - if I try using pin 24 as Chip Select (effectively ignoring whatever pin I gave this library, and instead using the automatic chip select), this library stops working.

[fridtjof]

I fixed this a long time ago in #10, by the way.