"been discussed before, the..." <- > <@dirbaio:matrix.org> been discussed before, the conclusion was kinda it's too tricky to add support for my recommendation is don't use SpiDevice, make your own trait "SdcardDevice" or something and write impls for it for (OutputPin, &RefCell), (OutputPin, &Mutex) etc Or maybe rather than a new trait, make a struct that owns an SpiBus and gives out its own special structs that impl SpiDevice